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  <title>编程之路</title>
  
  
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  <link href="/"/>
  <updated>2021-05-18T04:05:30.699Z</updated>
  <id>/</id>
  
  <author>
    <name>DLZ</name>
    
  </author>
  
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  <entry>
    <title>负面情绪</title>
    <link href="/2021/05/2021/05/%E8%B4%9F%E9%9D%A2%E6%83%85%E7%BB%AA/"/>
    <id>/2021/05/2021/05/负面情绪/</id>
    <published>2021-05-17T16:00:00.000Z</published>
    <updated>2021-05-18T04:05:30.699Z</updated>
    
    <content type="html"><![CDATA[<p>…<br><a id="more"></a></p><p>还是想写点日记，可能是晚上听了一些话，让自己心里有点不舒服。尽管自己给了自己一些心理暗示，但是夜深人静的时候，还是感觉到了自己内心的负面情绪。自卑、嫉妒、焦虑、愧疚、急于表现自己、急躁、不甘，无助。 一时间找不到支持自己努力工作的点。</p><p>是为了让自己变成能力更强的人吗？可是自己还是很差劲、比不上别人。是为了把一项任务出色的完成吗？可是任务似乎是无穷无尽的，而自己遇到问题时还是一样的不知所措，可笑。 每天过得那么累，却感觉没有收获。 </p><hr><p>作为一个人，一个独立的生命，当不知所措、感觉到不对劲、意识到负面情绪产生的时候，应该从自己的内心寻求答案。一切负面情绪都来源于我们的内心，可能事情无法避免，但是事情是客观的，客观的事情没有完全决定了主观的情绪，我生来会有情绪，但不意味着我不能控制自己的情绪。傻逼需求跟我的愤怒没有必然的联系，生产环境问题的出现跟我的紧张没有必然的联系，别人的质疑、嘲讽理论上我也可以不紧张、不怀疑自己、不生气。 </p><p>负面情绪实在是累赘，对我来说，工作的难度是 1，工作时的负面情堵带来的难度就是 2，无形中承受了许多不必要的痛苦。一直以来，负面情绪比思路还得更快。甩掉累赘，生活似乎又变得轻松了许多。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;…&lt;br&gt;
    
    </summary>
    
      <category term="日记" scheme="/categories/%E6%97%A5%E8%AE%B0/"/>
    
    
  </entry>
  
  <entry>
    <title>做事的方法论</title>
    <link href="/2021/03/2021/03/%E5%81%9A%E4%BA%8B%E7%9A%84%E6%96%B9%E6%B3%95%E8%AE%BA/"/>
    <id>/2021/03/2021/03/做事的方法论/</id>
    <published>2021-03-09T16:00:00.000Z</published>
    <updated>2021-03-10T09:36:28.082Z</updated>
    
    <content type="html"><![CDATA[<p>为什么比怎么做重要得多，没有想明白做一件事的目的，就很难把事情做好，即便做成了也可能浪费了很多时间，甚至只是运气好。<br><a id="more"></a><br>开始做一件事情之前，列出有哪些步骤，这是一般的做法。但这只是表面，因为这种情况下，能想到的步骤，大概率是模仿，或者是说抄袭别人的。不能否定模仿和抄袭的意义，因为别人这么做肯定有他的原因，别人肯定也是权衡过利弊的，但是未必我们和别人的目的不一样、现有的资源也不一样，直接照搬属实是愚蠢。</p><p>即便不是照搬，直接列出各个步骤也不是最好的方案。因为我们最终要解决的问题都没弄明白，思考得越多可能越偏离我们的目标。</p><p>啊，这个道理实在是简单。那为什么我之前没有这么做呢？</p><p>可能我们的大脑就不喜欢思考，而更喜欢看到成果，即使所谓的成果最后会变成废品。</p><p>回想去年做的那么多外包，包括今年，都可以作为反面教材：把项目看成是一个个功能，所谓做项目就是开发这些功能。结果给客户看的时候，发现人家要的不是这个样子的，又或者有些对客户很重要的功能没有开发，一来一回浪费了很多时间和精力，做了很多无用功。以前觉得是原型的问题，没有一开始让客户看到软件的样子，没有一开始跟客户确定好。但是我现在觉得不是这个问题，首先原型图不能画到非常完整，很多细节只有到开发的时候才能想到，其次，可能客户一开始也不知道自己原来需要 XX 功能。身为技术服务团队，也可以叫做外包，但不管叫什么，都应该替客户着想，先听取客户的需求，然后分析客户的需求，不合理的争取去掉，有必要但没有提的建议加上去。最终目的不是实现客户的需求然后拿钱，而是挖掘客户的需求、优化客户的工作流，为客户提供最好的解决方案。</p><p>不过说得简单，做起来不容易，而且即便真这么做了，也要做好心里准备，毕竟这是必要条件，而不是充分条件，事情还是可能搞砸。</p><p>思考之后的结果，也是分成很多个步骤，不过跟一开始列出的步骤肯定不一样。这个时候就一步步实施这些步骤，如果实施过程中有新的思考，也可以对计划进行优化。</p><p>另外，光思考远远不够，我们还需要往脑子里装入新的东西、新的概念，来帮助我们思考出更好的结果。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;为什么比怎么做重要得多，没有想明白做一件事的目的，就很难把事情做好，即便做成了也可能浪费了很多时间，甚至只是运气好。&lt;br&gt;
    
    </summary>
    
      <category term="工作" scheme="/categories/%E5%B7%A5%E4%BD%9C/"/>
    
    
  </entry>
  
  <entry>
    <title>不要为自己的作品感到丢脸</title>
    <link href="/2021/01/2021/isb/"/>
    <id>/2021/01/2021/isb/</id>
    <published>2021-01-11T16:00:00.000Z</published>
    <updated>2021-01-11T18:24:15.443Z</updated>
    
    <content type="html"><![CDATA[<p>凡是自己做出来的东西，都关系着自己的脸面。<br><a id="more"></a><br>对于一些事情，我可以不在乎脸面，比如说我游戏打得菜，说我又穷又丑，这些都无所谓。可是对于一些事情，我不得不在意，因为我就是靠这些事情吃饭的，如果这些事情都做不好，那么可以从楼上跳下去了。</p><p>喷一下自己：</p><p>你写的什么 jb 定时任务，能把服务器 CPU 跑满？如果这是一台很重要的服务器，并且有很多人正在用，那怎么办呢，重启服务器？你怎么不把你自己重启一下？上线服务之前不会用脑子想想会不会有什么影响吗？不知道定时任务运行的时候先判断一下上一个进程是否还在运行吗？定时任务处理失败的时候，不知道告警通知吗？一天天的一点小事都处理不好，以后那什么去应付稍微大一些的项目？</p><p>测试服务器和正式服务器理解不了吗？正式环境部署到测试服务器上面，脑子里面装的都是狗屎吗？这是一个有工作经验的人应该做出来的事情吗？</p><p>是得有多傻逼，才有把数据库删了那么多次，虽然是本地的数据库，可是这种事情为什么会发生那么多次呢，难道做事情的时候不知道自己在干嘛吗？想过那么多次定时备份数据库，找到解决方案了吗？真的脑残，还做个屁的开发。</p><p>总是看到别人做得不好的地方，为什么不审视一下自己呢？做项目难道真的就是功能跑通就可以了吗，难道你就这点追求吗。用户体验不用管了是吗，产品的逻辑存在问题看不到吗？问题留着留着自己就消失了吗，那么多问题为什么不能理清楚，然后花时间去解决呢。总说做得差不多了，确实可以跑完现有的流程，可是距离真实使用还有很长的一段距离，为什么不想方设法把问题解决呢？产品不仅仅是一个软件，它属于客户，面向用户，关系着公司的形象，同时也是每一个开发人员能力的体现。身为开发这个产品的一员，有责任去思考如何把产品做得更好。如果对公司不认可，完全可以离开，但是身在其中，就应该花心思做好每一个经手的产品，直到自己满意，直到自己觉得无可挑剔。</p><p>为什么你说话总是那么没底气，产品明明是你在做，为什么当别人问起的时候，你是如此的不自信，甚至背后的逻辑都说不明白。你说你忘了，但是这不应该出现。简单的逻辑你不会忘，即使忘了你想一下就知道，甚至别人都不用问你。复杂的逻辑你记不住，很可能是因为这只是你当时想出来的一个解决方案，为了满足需求，没有思考总结和归纳，导致你也不知道为什么这么做，也不知道有没有更好的方式去实现，更没有思考这样的实现是否存在潜在的问题，更不用说总结经验为下一次做准备了。</p><p>时间并没有想象中那么稀缺，可能你确实有点辛苦，但是很多辛苦是可以避免的，很多辛苦其实是在弥补之前自己没有选择正确的方式（甚至没有思考什么是正确的方式）。</p><p>多思考厉害的人会怎么做，多思考在不同情况下该如何应对。</p><p>不需要别人的认可，如果认为别人说得不对完全可以不听，但是凡事要先过自己这一关。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;凡是自己做出来的东西，都关系着自己的脸面。&lt;br&gt;
    
    </summary>
    
      <category term="工作" scheme="/categories/%E5%B7%A5%E4%BD%9C/"/>
    
    
  </entry>
  
  <entry>
    <title>一个工作习惯</title>
    <link href="/2020/12/2020/%E4%B8%80%E4%B8%AA%E5%B7%A5%E4%BD%9C%E4%B9%A0%E6%83%AF/"/>
    <id>/2020/12/2020/一个工作习惯/</id>
    <published>2020-12-10T16:00:00.000Z</published>
    <updated>2020-12-10T17:42:48.884Z</updated>
    
    <content type="html"><![CDATA[<p>突然觉得自己工作处于一种浑浑噩噩的状态。</p><a id="more"></a><p>虽然一直在做项目，也多多少少有一些进度，但是没有给自己制定计划，没有明确自己在某个时间点应该完成到什么程度。</p><p>也不是说这种状态就完全是错的。如果我只考虑当前涉及到的业务，把这一部分实现之后再去考虑其他部分，那这样最终也可以完成任务。</p><p>我现在觉得这种状态是错的，是因为我深刻体会到了这么做背后的痛苦。我们是根据业务的需求去开发，可以说业务需求决定了我们如何设计这个项目。比如 A 需求，通过方案一可以很好地实现，但是后面发现 A 需求跟 B 模块有关联，现有的方案无法优雅地实现。所以现在算是什么情况呢？现在是需求没变，只是发现了之前遗漏掉的一些关联，导致项目部分代码需要重构。项目都没有做完，就要把一部分代码重构，而且这部分代码没有问题，只是无法满足需求。这实在是一件可笑且可悲的事情。</p><p>项目需要重构很正常，但是还没有做完就要重构，那么一定是哪里出了问题。</p><p>我们应该在开发之前梳理业务的流程，在梳理的时候应该能够用自己的话说出来，这里的说主要是为了检查自己能否将这个功能进行抽象。进行抽象的好处是让自己能够以更高的视角看待项目，让业务流程看起来更加清晰，本质上就是化繁为简。同样的功能，可能有很复杂的实现，也可能有很简单的实现（注意我这里说的是“可能”而非“可以”）。</p><p>对于一项不熟悉的任务，很难一开始就给出合适的解决方案，甚至开始时都无法判断一个方案是否可行。如果说犯错在所难免，那么我们应该尽早的将错误暴露出来：模拟使用某个方案，深入体会该方案是否足够简单，是否完全满足需求。这件事并不简单，因为凭空想象很难，深入到每一个细节也是需要花很多时间的。但是在脑海中模拟完整的业务流程是很有价值的，因为这样做可以最小化试错成本（除非自己对于业务非常熟悉，有过这部分的经验）。</p><p>胡说八道了那么多，标题所指的工作习惯究竟是什么呢？其实就是在做一些没有完全把握的功能时，要学会去抽象这个功能，要完整地梳理完业务中的每一个流程，思考它们之间的关系，提出业务中的不合理性，最终给出合理的解决方案。（让一个开发去做这些事情，实在是过分。此外，更过分的是客户的需求可能会发生改变，意味着很多付出都白费掉了，不过解决方法很简单：加钱）</p><p>明确自己的任务，将思考和执行分开：前期光是思考，一行代码都不要写。后期光是执行，按照计划实现就好。当任务明确之后，就可以评估任务完成的时间，让自己有目标，也看得到自己完成了哪些任务，而不至于浑浑噩噩不知道要做什么，也不知道做了什么。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;突然觉得自己工作处于一种浑浑噩噩的状态。&lt;/p&gt;
    
    </summary>
    
      <category term="工作" scheme="/categories/%E5%B7%A5%E4%BD%9C/"/>
    
    
  </entry>
  
  <entry>
    <title>十一月的第一天</title>
    <link href="/2020/11/2020/%E5%8D%81%E4%B8%80%E6%9C%88%E7%9A%84%E7%AC%AC%E4%B8%80%E5%A4%A9/"/>
    <id>/2020/11/2020/十一月的第一天/</id>
    <published>2020-10-31T16:00:00.000Z</published>
    <updated>2020-11-01T16:08:42.428Z</updated>
    
    <content type="html"><![CDATA[<p>不知不觉已经一年多没有写过博客了，换一个说法：自从出来工作以后，就没有再写过博客了。</p><a id="more"></a><p>时间过得真快，不知不觉 2020 年都快过去了。公司今年从大学城搬到科韵路，我也从穗石村搬到了岗元新村，一眨眼已经 7 个月了。</p><p>今天是周日，我完全有时间也有兴趣写代码，我可以学如何写一个 composer 包、npm 包，也可以继续学习 Go 的协程，也可以研究 Laravel + Vue 的管理后台的权限控制。</p><p>不过，我并没有写代码，而是选择了打游戏。</p><p>因为我觉得自己需要脱离一下工作的状态，我有一种感觉：我在做自己喜欢的事情，但是是以一种我不喜欢的方式在做。之所以会有这种感觉，可能是这一周的工作太赶了。另一方面，觉得这么赶其实意义没什么意义。</p><p>我需要完成的工作还有很多，这些工作实际上都已经延期了，而且我还不确定什么时候可以完成。而这一周，精力都放在另一个我看来没那么重要的项目上面了。赶进度的结果就是留了很多坑要填。</p><p>回头看看自己这几个月的工作，我不知道如何形容。如果只用一个词来描述的话，我只想说两个字：垃圾。表面上看起来我是三个项目一起在做，可是实际上是一个都没有做好。</p><p>究其原因，一个很大的因素是：在前端花掉了太多的时间。我跟同事说过：我有三分之一的时间在写服务端，有三分之一的时间在写管理后台，还有三分之一的时间在想业务的流程该是什么样子的。一开始以为三个项目都挺简单的，习惯性一边写接口一边写管理端，直至业务的流程变了两三次，也没有想到要兼顾三个项目的进度，没有想到要把一部分的工作交给同事去做。导致了同事有时间，但是没有接口去调。项目延期跟我有直接关系，但我仍然觉得根本原因在于整个项目的把控。如果业务流程一开始足够清晰，不需要在开发阶段就调整两三次，不需要我写到的时候再去想、再去问，能节约一部分时间。如果业务流程足够清晰，原型图足够完成，那么设计师和前端也可以一开始就完成前端界面的设计，而不是等到后面才意识到：这里还少一个界面。</p><p>另一个重要因素是我没有规划，这一点在上面也提到了。正确的做法应该是，在正式写代码之前，把要做的事情全部列出来。至少要把某一个部分的细节全部列出来，从数据结构，到数据的新建、数据的修改，数据的查询和筛选，以及数据之间的关联。因为它们之间可能会相互的影响，后者可能会影响前者的设计，如果一开始没有考虑周到，就可能刚开始可能就会做无用功。</p><p>以前我都是只关注某一个点，没有全局的规划。导致后面才发现原来的逻辑跑不通，这个时候才去问，如果可以早点思考，就能减少一些这样的情况。另一方面，可以给自己定目标，当时间不足时，可以忽略一些不重要的东西，把精力放在主流程上面，而不是在某一个小点上浪费过多的时间。</p><p>不早了，到睡觉的时间了，睡眠是最重要的。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;不知不觉已经一年多没有写过博客了，换一个说法：自从出来工作以后，就没有再写过博客了。&lt;/p&gt;
    
    </summary>
    
      <category term="生活" scheme="/categories/%E7%94%9F%E6%B4%BB/"/>
    
    
  </entry>
  
  <entry>
    <title>奇葩问题：IDEA 中正确运行，命令行运行就出错</title>
    <link href="/2019/07/articles/bug%20-%20IDEA%20%E4%B8%AD%E6%AD%A3%E7%A1%AE%E8%BF%90%E8%A1%8C%EF%BC%8C%E5%91%BD%E4%BB%A4%E8%A1%8C%E8%BF%90%E8%A1%8C%E5%87%BA%E9%94%99/"/>
    <id>/2019/07/articles/bug - IDEA 中正确运行，命令行运行出错/</id>
    <published>2019-07-28T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.932Z</updated>
    
    <content type="html"><![CDATA[<p>同一个世界，同一份代码，不同的结果。<br><a id="more"></a></p><h1 id="问题描述"><a href="#问题描述" class="headerlink" title="问题描述"></a>问题描述</h1><p>简单来说，就是一个项目在 IDEA 中可以正常运行，打成 jar 包之后，通过 <code>java -jar</code> 在命令行运行就出错。</p><p>具体来说：</p><p>这是一个 Spring Boot 项目，在 service 层发出一个 HTTP 请求。</p><p>在 IDEA 运行的时候，能得到正确的 json 数据，在命令行中就只得到“未知错误”的提示。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-07-29_17-28-18.png" alt></p><h1 id="解决过程"><a href="#解决过程" class="headerlink" title="解决过程"></a>解决过程</h1><h2 id="HTTP-request"><a href="#HTTP-request" class="headerlink" title="HTTP request"></a>HTTP request</h2><p>既然是 HTTP 的 response 不同，首先想到的是比较一下两处的 request 有何不同。</p><p><em>查看 okhttp 中请求主体的方法：</em></p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">private</span> <span class="keyword">static</span> String <span class="title">bodyToString</span><span class="params">(<span class="keyword">final</span> Request request)</span></span>&#123;</span><br><span class="line">    <span class="keyword">try</span> &#123;</span><br><span class="line">        <span class="keyword">final</span> Request copy = request.newBuilder().build();</span><br><span class="line">        <span class="keyword">final</span> Buffer buffer = <span class="keyword">new</span> Buffer();</span><br><span class="line">        copy.body().writeTo(buffer);</span><br><span class="line">        <span class="keyword">return</span> buffer.readUtf8();</span><br><span class="line">    &#125; <span class="keyword">catch</span> (<span class="keyword">final</span> IOException e) &#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="string">"did not work"</span>;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p>然而，两种方式发出的 HTTP request 好像都很正常，除去一些会变化的字符串外，请求主体一模一样。（这里<strong>会变化的字符串</strong>指的是时间戳、MD5 加密得到的字符串等，它们每次运行都是不一样的值）</p><p>此时应该将字符串写死，再对比两者的不同。</p><p>但是因为改起来太麻烦，加上以前的经验，我选择对请求主体中的字符进行 URL 编码，事实证明这是一个愚蠢的行为，它导致了在 IDEA 中也得不到想要的结果。</p><p>第一次尝试宣告失败。</p><h2 id="为-okhttp-设置代理"><a href="#为-okhttp-设置代理" class="headerlink" title="为 okhttp 设置代理"></a>为 okhttp 设置代理</h2><p>使用下面的方式创建 OkHttpClient 就能在 Fidder 中捕获到 okhttp 发送和接收的数据了。</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">String hostname = <span class="string">"localhost"</span><span class="comment">/*127.0.0.1*/</span>;</span><br><span class="line"><span class="keyword">int</span> port = <span class="number">8888</span>;</span><br><span class="line">System.out.println(<span class="string">"设置代理"</span>);</span><br><span class="line">Proxy proxy = <span class="keyword">new</span> Proxy(Proxy.Type.HTTP,</span><br><span class="line"><span class="keyword">new</span> InetSocketAddress(hostname, port));</span><br><span class="line"></span><br><span class="line"><span class="keyword">this</span>.client = <span class="keyword">new</span> OkHttpClient().newBuilder().proxy(proxy).build();</span><br></pre></td></tr></table></figure><p>这里的思路是：不单单对比请求主体，而是通过 Fidder 更细致地比较两次 HTTP 请求的区别。</p><p>确实可以捕获到程序发出的 HTTP 请求，但是跟刚才一样，除去一些会变化的值，两者几乎是一样的。</p><p>第二次尝试也没有发现有用的信息。</p><h2 id="MD5"><a href="#MD5" class="headerlink" title="MD5"></a>MD5</h2><p>还是回到最初的疑惑：明明是一样的代码，而且是同一台电脑上，为什么得到不一样的结果？</p><p>同样的代码，难道会计算出不一样的 Hash Value ？</p><p><strong>是的。</strong></p><p>可能是直觉，也可能是实在没有思路了，所以猜测是 sign 字段（通过 MD5 算法生成）的问题。</p><p>很快验证出的确是 sign 字段有问题，但是怎么解决呢？</p><p>因为不知道在命令行运行时怎么 debug，所以一切都变得很麻烦。</p><p>经过慢慢的试验，一步步打印出来，最后发现进行摘要的字符串其实是一样的，但是得到的结果却不一样。</p><p>很明显是摘要算法有问题。</p><p>这个方法是我在网上复制的，难道它在命令行中执行会得到不一样的结果？</p><p>我又在网上搜了其他的 MD5 代码，但是还是一样出错。（如果此时运行对了，可能我永远都不会知道问题真正的原因了）。</p><p>最终用我的工地英语在谷歌搜索：<code>java cmd md5 digest difference</code>，然后看到<a href="https://stackoverflow.com/questions/6928641/will-java-messagedigest-generated-different-md5-hash-on-different-jdk-version" target="_blank" rel="noopener">这篇回答</a>，才知道因为 MD5 算法中，要将字符串转换成 byte[]，而 IDEA 和命令行的编码不同，导致得到的 byte[] 不同，进而导致 sign 不同。</p><p><em>在计算 Hash Value 的时候指定编码。</em></p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">byte</span>[] array = md.digest(str.getBytes(<span class="string">"UTF-8"</span>));</span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>虽然解决这个问题只需要改一行代码，但是整个过程却花了我很多时间，做了太多太多无谓的尝试。</p><p>不过还好，还是解决了。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/psb.webp" alt></p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;同一个世界，同一份代码，不同的结果。&lt;br&gt;
    
    </summary>
    
      <category term="Java" scheme="/categories/Java/"/>
    
    
      <category term="java" scheme="/tags/java/"/>
    
      <category term="bug" scheme="/tags/bug/"/>
    
  </entry>
  
  <entry>
    <title>对 Java 中流的理解</title>
    <link href="/2019/07/articles/%E5%AF%B9%20Java%20%E4%B8%AD%E6%B5%81%E7%9A%84%E7%90%86%E8%A7%A3/"/>
    <id>/2019/07/articles/对 Java 中流的理解/</id>
    <published>2019-07-16T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.935Z</updated>
    
    <content type="html"><![CDATA[<p>通过表达整理自己的思路，但不一定正确。<br><a id="more"></a></p><p>以前学习 Java 中文件和流的时候，理解不深，当时又觉得很少用 Java 操作文件，所以就没有好好看，导致对于“文件”和“流”这两个概念都分不清。</p><p>印象中只记得有好多个类，记不得有多少个，更分不清各自有什么用，结果现在看不懂别人的代码了，所以再学习一下，争取能看懂。</p><h1 id="文件和流"><a href="#文件和流" class="headerlink" title="文件和流"></a>文件和流</h1><p>Java 提供了文件相关的类，和流相关的类，以前感觉都差不多。实际上前者主要是操作文件（比如删除、复制等），而不是进入文件中读取文件的数据。而后者是读写文件中的内容。</p><p>假设有一个 a.txt 文件，与文件相关的类，可以将它删除、改名。而与流相关的类，可以读取 a.txt 里面的内容，或者修改 a.txt 里面的内容。</p><p>上面是 Java 中类的区别，那么“文件”和“流”这两个名词各自是什么意思呢？</p><p>文件就是电脑里存在的文件：文本文件、图片文件、视频文件等等。</p><p>至于流，真的不好理解，网上有些说对数据的读、写是流，有的说文件就是流，以前认为流是内存和数据之间的通道。整半天没搞懂，迫于找不到通俗易懂的解释，所以根据网上的理解，自己瞎猜。</p><p>从实际应用的角度看，程序可能需要从外部读取数据，比如从硬盘中读取数据、从网络中获取数据。这些操作类似，不如将它们抽象化，用一个类表示，这也刚好符合面向对象的思想。</p><p>看到这里，我想说的是，不要单独去理解什么是流。（忘掉流吧，我偷电瓶养你）</p><p>直接从 InputStream 开始理解，它是一个抽象类，既然是类就应该可以用来表示某一类事物（就像 Person 类可以表示人一样）。所以 InputStream 就可以看成是<strong>所有可以读取到数据的东西</strong>。不过是硬盘，还是键盘，只要我可以从你那里读取到数据，你就是 InputStream（输入流）。</p><p>OutputStream 也是同样的道理，我往硬盘写数据的时候，硬盘就是 OutputStream（输出流）。</p><p>理解的前提是忘掉“流”，“流”只不过是类名里的最后一个字，如果设计者喜欢，叫做 OutputBlock 又有何不可呢？其次是牢记在 Java 中类是为了表示一类事物，InputStream 和 OutputStream 也不例外。</p><h1 id="常见的类及其描述"><a href="#常见的类及其描述" class="headerlink" title="常见的类及其描述"></a>常见的类及其描述</h1><h2 id="Some-important-Byte-stream-classes"><a href="#Some-important-Byte-stream-classes" class="headerlink" title="Some important Byte stream classes."></a>Some important Byte stream classes.</h2><table><thead><tr><th>Stream class</th><th>Description</th></tr></thead><tbody><tr><td><strong>BufferedInputStream</strong></td><td>Used for Buffered Input Stream.</td></tr><tr><td><strong>BufferedOutputStream</strong></td><td>Used for Buffered Output Stream.</td></tr><tr><td><strong>DataInputStream</strong></td><td>Contains method for reading java standard datatype</td></tr><tr><td><strong>DataOutputStream</strong></td><td>An output stream that contain method for writing java standard data type</td></tr><tr><td><strong>FileInputStream</strong></td><td>Input stream that reads from a file</td></tr><tr><td><strong>FileOutputStream</strong></td><td>Output stream that write to a file.</td></tr><tr><td><strong>InputStream</strong></td><td>Abstract class that describe stream input.</td></tr><tr><td><strong>OutputStream</strong></td><td>Abstract class that describe stream output.</td></tr><tr><td><strong>PrintStream</strong></td><td>Output Stream that contain <code>print()</code> and <code>println()</code> method</td></tr></tbody></table><h2 id="Some-important-Charcter-stream-classes"><a href="#Some-important-Charcter-stream-classes" class="headerlink" title="Some important Charcter stream classes."></a>Some important Charcter stream classes.</h2><table><thead><tr><th>Stream class</th><th>Description</th></tr></thead><tbody><tr><td><strong>BufferedReader</strong></td><td>Handles buffered input stream.</td></tr><tr><td><strong>BufferedWriter</strong></td><td>Handles buffered output stream.</td></tr><tr><td><strong>FileReader</strong></td><td>Input stream that reads from file.</td></tr><tr><td><strong>FileWriter</strong></td><td>Output stream that writes to file.</td></tr><tr><td><strong>InputStreamReader</strong></td><td>Input stream that translate byte to character</td></tr><tr><td><strong>OutputStreamReader</strong></td><td>Output stream that translate character to byte.</td></tr><tr><td><strong>PrintWriter</strong></td><td>Output Stream that contain <code>print()</code> and <code>println()</code> method.</td></tr><tr><td><strong>Reader</strong></td><td>Abstract class that define character stream input</td></tr><tr><td><strong>Writer</strong></td><td>Abstract class that define character stream output</td></tr></tbody></table><p>具体的类就不研究怎么用了，估计使用得最多的就是 Bufferedxxx 了。</p><h1 id="示例"><a href="#示例" class="headerlink" title="示例"></a>示例</h1><p>下面这段代码的意思是：</p><ol><li>获取到字节输入流</li><li>将字节输入流转换成字符输入流</li><li>再转换成缓冲字符输入流</li><li>然后在逐行读取内容</li></ol><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line">InputStream inputStream =  request.getInputStream();</span><br><span class="line"></span><br><span class="line"><span class="comment">//BufferedReader是包装设计模式，性能更高</span></span><br><span class="line">BufferedReader in = <span class="keyword">new</span> BufferedReader(<span class="keyword">new</span> InputStreamReader(inputStream,<span class="string">"UTF-8"</span>));</span><br><span class="line">StringBuffer sb = <span class="keyword">new</span> StringBuffer();</span><br><span class="line">String line ;</span><br><span class="line"><span class="keyword">while</span> ((line = in.readLine()) != <span class="keyword">null</span>)&#123;</span><br><span class="line">    sb.append(line);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p>创建一个 BufferedReader 之前还要先创建一个 InputStreamReader，这看起来很麻烦，为什么不直接创建缓冲字符输入流呢？</p><p>首先，因为要从不同的设备中读取数据，所以需要设计多个类，而每个类都可能需要用到缓冲这个功能，如果再为每个类设计一个具有缓冲功能的类，那么类的数目将会翻一倍。</p><p>所以 BufferedReader 被设计为：接收一个字符输入流，并具有缓冲的功能，虽然使用上麻烦了一点，但是还是可以接受的，不然更多的类需要去记。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;通过表达整理自己的思路，但不一定正确。&lt;br&gt;
    
    </summary>
    
      <category term="Java" scheme="/categories/Java/"/>
    
    
  </entry>
  
  <entry>
    <title>Linux 安装 nginx</title>
    <link href="/2019/05/articles/Linux%20%E5%AE%89%E8%A3%85%20nginx/"/>
    <id>/2019/05/articles/Linux 安装 nginx/</id>
    <published>2019-05-13T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.927Z</updated>
    
    <content type="html"><![CDATA[<p>记录在 Linux 安装 nginx 的过程。</p><a id="more"></a><h1 id="下载"><a href="#下载" class="headerlink" title="下载"></a>下载</h1><p><a href="http://nginx.org/en/download.html" target="_blank" rel="noopener">下载地址</a></p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">wget http://nginx.org/download/nginx-1.16.0.tar.gz</span><br></pre></td></tr></table></figure><h1 id="解压"><a href="#解压" class="headerlink" title="解压"></a>解压</h1><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">tar -zvxf nginx-xxx.tar.gz</span><br></pre></td></tr></table></figure><h1 id="配置"><a href="#配置" class="headerlink" title="配置"></a>配置</h1><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">./configure</span><br></pre></td></tr></table></figure><h1 id="可能需要安装的库"><a href="#可能需要安装的库" class="headerlink" title="可能需要安装的库"></a>可能需要安装的库</h1><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">yum install -y httpd-devel pcre perl pcre-devel zlib zlib-devel GeoIP GeoIP-devel</span><br></pre></td></tr></table></figure><h1 id="安装"><a href="#安装" class="headerlink" title="安装"></a>安装</h1><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">make install</span><br></pre></td></tr></table></figure><h1 id="启动"><a href="#启动" class="headerlink" title="启动"></a>启动</h1><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /usr/local/nginx/sbin</span><br><span class="line">./nginx</span><br></pre></td></tr></table></figure>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;记录在 Linux 安装 nginx 的过程。&lt;/p&gt;
    
    </summary>
    
      <category term="nginx" scheme="/categories/nginx/"/>
    
    
  </entry>
  
  <entry>
    <title>Bootstrap4 Dropdown 组件扩展 hover 事件</title>
    <link href="/2019/05/articles/Bootstrap%20Dropdown%20%E4%BF%AE%E6%94%B9%E8%A7%A6%E5%8F%91%E4%BA%8B%E4%BB%B6/"/>
    <id>/2019/05/articles/Bootstrap Dropdown 修改触发事件/</id>
    <published>2019-05-10T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.921Z</updated>
    
    <content type="html"><![CDATA[<p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/19051201.gif" alt></p><a id="more"></a><p>效果如图所示，很简单的一个功能，但是因为我在这上面花了很多时间，所以我决定把它记录下来。</p><h1 id="官方文档"><a href="#官方文档" class="headerlink" title="官方文档"></a>官方文档</h1><p><a href="https://getbootstrap.com/docs/4.0/components/dropdowns/" target="_blank" rel="noopener">Dropdowns · Bootstrap </a></p><h1 id="示例"><a href="#示例" class="headerlink" title="示例"></a>示例</h1><p>Bootstrap 提供的下拉菜单默认是通过鼠标点击触发，下面是一个简单的完整示例。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/2019051201.gif" alt></p><figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">&lt;!DOCTYPE html&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">html</span> <span class="attr">lang</span>=<span class="string">"en"</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;<span class="name">head</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">charset</span>=<span class="string">"UTF-8"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">name</span>=<span class="string">"viewport"</span> <span class="attr">content</span>=<span class="string">"width=device-width, initial-scale=1.0"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">http-equiv</span>=<span class="string">"X-UA-Compatible"</span> <span class="attr">content</span>=<span class="string">"ie=edge"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">title</span>&gt;</span>Document<span class="tag">&lt;/<span class="name">title</span>&gt;</span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">link</span> <span class="attr">rel</span>=<span class="string">"stylesheet"</span> <span class="attr">href</span>=<span class="string">"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"</span> <span class="attr">integrity</span>=<span class="string">"sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">head</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;<span class="name">body</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"container"</span>&gt;</span></span><br><span class="line">        <span class="comment">&lt;!-- Default dropright button --&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"btn-group dropright"</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">button</span> <span class="attr">type</span>=<span class="string">"button"</span> <span class="attr">class</span>=<span class="string">"btn btn-secondary dropdown-toggle"</span> <span class="attr">data-toggle</span>=<span class="string">"dropdown"</span> <span class="attr">aria-haspopup</span>=<span class="string">"true"</span></span></span><br><span class="line"><span class="tag">                <span class="attr">aria-expanded</span>=<span class="string">"false"</span>&gt;</span></span><br><span class="line">                Dropright</span><br><span class="line">            <span class="tag">&lt;/<span class="name">button</span>&gt;</span></span><br><span class="line"></span><br><span class="line">            <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-menu"</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Another action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Something else here<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-divider"</span>&gt;</span><span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Separated link<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://code.jquery.com/jquery-3.2.1.slim.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">body</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;/<span class="name">html</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="扩展-hover-事件"><a href="#扩展-hover-事件" class="headerlink" title="扩展 hover 事件"></a>扩展 hover 事件</h1><p>有时候希望鼠标放上去就展开菜单，而不需要鼠标点击，只需要一点简单的代码就可以实现：</p><figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">style</span>&gt;</span><span class="undefined"></span></span><br><span class="line"><span class="undefined">    .dropdown-menu &#123;</span></span><br><span class="line"><span class="undefined">        margin:0 !important;</span></span><br><span class="line"><span class="undefined">    &#125;</span></span><br><span class="line"><span class="undefined">    .dropright:hover &gt; .dropdown-menu &#123;</span></span><br><span class="line"><span class="undefined">        display:block;</span></span><br><span class="line"><span class="undefined">    &#125;</span></span><br><span class="line"><span class="undefined"></span><span class="tag">&lt;/<span class="name">style</span>&gt;</span></span><br></pre></td></tr></table></figure><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/19051202.gif" alt></p><p>为什么加上这几句就行了呢？因为 <code>dropdown-menu</code> 类的原来的样式是 <code>display:none;</code>，所以设置 <code>display:block;</code> 之后 <code>dropdown-menu</code> 就会显示出来了。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-05-12_12-07-15.png" alt></p><h1 id="问题一"><a href="#问题一" class="headerlink" title="问题一"></a>问题一</h1><p>当鼠标放上去时没有问题，但是如果鼠标点击之后就会<strong>出现问题</strong>。首先是位置，下拉菜单的位置改变了，其次是鼠标移走之后下拉菜单也不会自动关闭。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/19051203.gif" alt></p><h1 id="问题一的解决方法"><a href="#问题一的解决方法" class="headerlink" title="问题一的解决方法"></a>问题一的解决方法</h1><p>删掉 <code>button</code> 标签的  <code>data-toggle=&quot;dropdown&quot;</code>，这个方法看起来一点也不优雅，但是目前只能想到这个。</p><h1 id="问题二"><a href="#问题二" class="headerlink" title="问题二"></a>问题二</h1><p>本来下拉菜单是在右侧显示的，但是现在却是在下面显示。</p><h1 id="问题二的解决方法"><a href="#问题二的解决方法" class="headerlink" title="问题二的解决方法"></a>问题二的解决方法</h1><p>在 <code>&lt;style&gt;</code> 标签中添加：</p><figure class="highlight css"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="selector-class">.dropright</span> &#123;</span><br><span class="line">    <span class="attribute">position</span>: relative;</span><br><span class="line">&#125;</span><br><span class="line"><span class="selector-class">.dropdown-menu</span> &#123;</span><br><span class="line">    <span class="attribute">position</span>: absolute;</span><br><span class="line">    <span class="attribute">left</span>: <span class="number">100%</span>;</span><br><span class="line">    <span class="attribute">top</span>: <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>一开始我就搜到了解决办法，但是由于我太蠢了，看都不看直接复制，导致一直得不到想要的效果（根本原因是：别人的 HTML 代码跟官方示例不一样，所以直接复制过来自然没效果）。</p><p>后来找到了另一种方法，然后那个方法也有很大的缺陷：鼠标移走时下拉菜单不会关闭。尽管最后也解决了这个问题，但是效果并不好，而且有时还有 bug。</p><p>直到昨晚一点多终于搞明白了，一方面觉得自己真是蠢，抄代码都能抄歪来，另一方面没人分享自己的喜悦，所以有了这篇文章。</p><p>欢迎批评指点，如果对你有帮助那就更好了。</p><h1 id="完整代码"><a href="#完整代码" class="headerlink" title="完整代码"></a>完整代码</h1><figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">&lt;!DOCTYPE html&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">html</span> <span class="attr">lang</span>=<span class="string">"en"</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;<span class="name">head</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">charset</span>=<span class="string">"UTF-8"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">name</span>=<span class="string">"viewport"</span> <span class="attr">content</span>=<span class="string">"width=device-width, initial-scale=1.0"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">meta</span> <span class="attr">http-equiv</span>=<span class="string">"X-UA-Compatible"</span> <span class="attr">content</span>=<span class="string">"ie=edge"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">title</span>&gt;</span>Document<span class="tag">&lt;/<span class="name">title</span>&gt;</span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">link</span> <span class="attr">rel</span>=<span class="string">"stylesheet"</span> <span class="attr">href</span>=<span class="string">"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"</span> <span class="attr">integrity</span>=<span class="string">"sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">head</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;<span class="name">body</span>&gt;</span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">style</span>&gt;</span><span class="undefined"></span></span><br><span class="line"><span class="css">        <span class="selector-class">.dropdown-menu</span> &#123;</span></span><br><span class="line"><span class="css">            <span class="selector-tag">margin</span><span class="selector-pseudo">:0</span> !<span class="selector-tag">important</span>;</span></span><br><span class="line"><span class="undefined">        &#125;</span></span><br><span class="line"><span class="css">        <span class="selector-class">.dropright</span><span class="selector-pseudo">:hover</span> &gt; <span class="selector-class">.dropdown-menu</span> &#123;</span></span><br><span class="line"><span class="css">            <span class="selector-tag">display</span><span class="selector-pseudo">:block</span>;</span></span><br><span class="line"><span class="undefined">        &#125;</span></span><br><span class="line"><span class="css">        <span class="selector-class">.dropright</span> &#123;</span></span><br><span class="line"><span class="undefined">            position: relative;</span></span><br><span class="line"><span class="undefined">        &#125;</span></span><br><span class="line"><span class="css">        <span class="selector-class">.dropdown-menu</span> &#123;</span></span><br><span class="line"><span class="undefined">            position: absolute;</span></span><br><span class="line"><span class="undefined">            left: 100%;</span></span><br><span class="line"><span class="undefined">            top: 0;</span></span><br><span class="line"><span class="undefined">        &#125;</span></span><br><span class="line"><span class="undefined">    </span><span class="tag">&lt;/<span class="name">style</span>&gt;</span></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"container"</span>&gt;</span></span><br><span class="line">        <span class="comment">&lt;!-- Default dropright button --&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"btn-group dropright"</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">button</span> <span class="attr">type</span>=<span class="string">"button"</span> <span class="attr">class</span>=<span class="string">"btn btn-secondary dropdown-toggle"</span> <span class="attr">aria-haspopup</span>=<span class="string">"true"</span> <span class="attr">aria-expanded</span>=<span class="string">"false"</span>&gt;</span></span><br><span class="line">                Dropright</span><br><span class="line">            <span class="tag">&lt;/<span class="name">button</span>&gt;</span></span><br><span class="line"></span><br><span class="line">            <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-menu"</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Another action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Something else here<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-divider"</span>&gt;</span><span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Separated link<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">br</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"btn-group dropright"</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">button</span> <span class="attr">type</span>=<span class="string">"button"</span> <span class="attr">class</span>=<span class="string">"btn btn-secondary dropdown-toggle"</span> <span class="attr">aria-haspopup</span>=<span class="string">"true"</span> <span class="attr">aria-expanded</span>=<span class="string">"false"</span>&gt;</span></span><br><span class="line">                Dropright</span><br><span class="line">            <span class="tag">&lt;/<span class="name">button</span>&gt;</span></span><br><span class="line"></span><br><span class="line">            <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-menu"</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Another action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Something else here<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-divider"</span>&gt;</span><span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Separated link<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line"></span><br><span class="line">        <span class="tag">&lt;<span class="name">br</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"btn-group dropright"</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">button</span> <span class="attr">type</span>=<span class="string">"button"</span> <span class="attr">class</span>=<span class="string">"btn btn-secondary dropdown-toggle"</span> <span class="attr">aria-haspopup</span>=<span class="string">"true"</span> <span class="attr">aria-expanded</span>=<span class="string">"false"</span>&gt;</span></span><br><span class="line">                Dropright</span><br><span class="line">            <span class="tag">&lt;/<span class="name">button</span>&gt;</span></span><br><span class="line"></span><br><span class="line">            <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-menu"</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Another action<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Something else here<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">div</span> <span class="attr">class</span>=<span class="string">"dropdown-divider"</span>&gt;</span><span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">a</span> <span class="attr">class</span>=<span class="string">"dropdown-item"</span> <span class="attr">href</span>=<span class="string">"#"</span>&gt;</span>Separated link<span class="tag">&lt;/<span class="name">a</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">div</span>&gt;</span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://code.jquery.com/jquery-3.2.1.slim.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">script</span> <span class="attr">src</span>=<span class="string">"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"</span> <span class="attr">integrity</span>=<span class="string">"sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"</span></span></span><br><span class="line"><span class="tag">        <span class="attr">crossorigin</span>=<span class="string">"anonymous"</span>&gt;</span><span class="undefined"></span><span class="tag">&lt;/<span class="name">script</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;/<span class="name">body</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;/<span class="name">html</span>&gt;</span></span><br></pre></td></tr></table></figure>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;&lt;img src=&quot;https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/19051201.gif&quot; alt&gt;&lt;/p&gt;
    
    </summary>
    
      <category term="前端" scheme="/categories/%E5%89%8D%E7%AB%AF/"/>
    
    
  </entry>
  
  <entry>
    <title>Maven 聚合与继承</title>
    <link href="/2019/02/articles/Maven%20%E8%81%9A%E5%90%88%E4%B8%8E%E7%BB%A7%E6%89%BF/"/>
    <id>/2019/02/articles/Maven 聚合与继承/</id>
    <published>2019-02-10T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.929Z</updated>
    
    <content type="html"><![CDATA[<p>聚合是为了方便的构建多个项目，继承是为了简化 POM 的重复配置。</p><a id="more"></a><h1 id="聚合"><a href="#聚合" class="headerlink" title="聚合"></a>聚合</h1><p>一个实际的项目可能由多个“模块”组成，每个模块都是一个 Maven 项目。</p><p>这样就可能产生一个需求：同时构建多个 Maven 项目。此时如果进入到每个 Maven 项目的目录中，执行 mvn 命令进行构建就有点麻烦了。所以就有了“聚合”这个概念，聚合实际的作用就是同时构建多个 Maven 项目。</p><h1 id="聚合的步骤"><a href="#聚合的步骤" class="headerlink" title="聚合的步骤"></a>聚合的步骤</h1><p>要聚合模块其实很简单，就是创建一个 Maven 项目，然后在这个项目的 pom.xml 文件中声明要聚合的模块。</p><h2 id="目录结构"><a href="#目录结构" class="headerlink" title="目录结构"></a>目录结构</h2><p>举例，moduleB和 moduleC 是普通的模块，moduleA 是聚合模块，目录结构如下：</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-02-12_11-59-31.png" alt></p><p>需要注意的是：</p><ul><li>聚合模块下没有 src 目录，只有一个 pom.xml 文件。毕竟它只是起聚合模块的作用，不需要实际代码。</li><li>目录结构不一定是这样的，下面的 pom.xml 还可以配置聚合模块所在的目录。</li></ul><h2 id="moduleA-的-pom-xml"><a href="#moduleA-的-pom-xml" class="headerlink" title="moduleA 的 pom.xml"></a>moduleA 的 pom.xml</h2><p>注意点 ：</p><ul><li>packaging 元素必须为 pom</li><li>建议填写 name 标签的内容，因为执行 mvn 命令时将会输出该标签下的内容。（如果没有写，将输出 artifactId）</li><li>modules 下的每个 module 标签对应一个模块。<strong>注意 module 标签中的是模块的相对路径，也就是对这个 pom.xml 的相对路径。</strong></li></ul><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line">&lt;?xml version="1.0" encoding="UTF-8"?&gt;</span><br><span class="line"><span class="tag">&lt;<span class="name">project</span> <span class="attr">xmlns</span>=<span class="string">"http://maven.apache.org/POM/4.0.0"</span></span></span><br><span class="line"><span class="tag">         <span class="attr">xmlns:xsi</span>=<span class="string">"http://www.w3.org/2001/XMLSchema-instance"</span></span></span><br><span class="line"><span class="tag">         <span class="attr">xsi:schemaLocation</span>=<span class="string">"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">modelVersion</span>&gt;</span>4.0.0<span class="tag">&lt;/<span class="name">modelVersion</span>&gt;</span></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.test.modules<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>moduleC<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.0-SNAPSHOT<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">packaging</span>&gt;</span>pom<span class="tag">&lt;/<span class="name">packaging</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">name</span>&gt;</span>module A<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">modules</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">module</span>&gt;</span>../moduleA<span class="tag">&lt;/<span class="name">module</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">module</span>&gt;</span>../moduleB<span class="tag">&lt;/<span class="name">module</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">modules</span>&gt;</span></span><br><span class="line">    </span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><h2 id="使用"><a href="#使用" class="headerlink" title="使用"></a>使用</h2><p>在 moduleA 目录下执行 Maven 命令即可。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-02-12_12-26-23.png" alt></p><h1 id="继承"><a href="#继承" class="headerlink" title="继承"></a>继承</h1><p>这里的继承指的是 pom.xml 的继承，因为多个 Maven 项目可能存在多个相同的配置，使用继承就可以减少一些配置。</p><p>怎么做呢？</p><p>简单来说就是创建一个 Maven 项目，它的 pom.xml 作为父POM，然后在其他项目中通过坐标引入这个父项目，这样子POM将会继承父POM的一些配置。</p><h2 id="举例"><a href="#举例" class="headerlink" title="举例"></a>举例</h2><p>聚合与继承不一样，但是不冲突，刚才的 moduleA 是聚合模块，同时 moduleA 的 pom.xml 也可以作为父POM。</p><p>使用了继承之后的 moduleB 的 pom.xml：</p><p>注意点：</p><ul><li>使用 parent 标签继承 moduleA</li><li>使用坐标定位 moduleA</li><li>relativePath 对应 moduleA 的相对目录<ul><li>默认值是 <code>../pom.xml</code></li><li>如果在这里的目录找不到，将会在本地仓库查找</li><li>最好写上 relativePath</li></ul></li><li>在 moduleB 的 pom.xml 中不用写 <code>groupId</code> 和 <code>artifactId</code>，因为会从 moduleA 的 pom.xml 中继承。<ul><li>如果和父POM不一样，也可以写上去。</li></ul></li></ul><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line">&lt;?xml version="1.0" encoding="UTF-8"?&gt;</span><br><span class="line"><span class="tag">&lt;<span class="name">project</span> <span class="attr">xmlns</span>=<span class="string">"http://maven.apache.org/POM/4.0.0"</span></span></span><br><span class="line"><span class="tag">         <span class="attr">xmlns:xsi</span>=<span class="string">"http://www.w3.org/2001/XMLSchema-instance"</span></span></span><br><span class="line"><span class="tag">         <span class="attr">xsi:schemaLocation</span>=<span class="string">"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">modelVersion</span>&gt;</span>4.0.0<span class="tag">&lt;/<span class="name">modelVersion</span>&gt;</span></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>moduleB<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line"></span><br><span class="line">    <span class="tag">&lt;<span class="name">parent</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.test.modules<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>moduleA<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.0-SNAPSHOT<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">relativePath</span>&gt;</span>../moduleA<span class="tag">&lt;/<span class="name">relativePath</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">parent</span>&gt;</span></span><br><span class="line">    </span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="可以继承的-POM-元素"><a href="#可以继承的-POM-元素" class="headerlink" title="可以继承的 POM 元素"></a>可以继承的 POM 元素</h1><ul><li>groupId 项目组 ID</li><li>version 项目版本</li><li>description 项目的描述信息</li><li>organization 项目的组织信息</li><li>inceptionYear 项目的创始年份</li><li>url 项目的 URL 地址</li><li>developers 项目的开发者信息</li><li>contributors 项目的贡献者信息</li><li>distributionManagement 项目的部署配置</li><li>issueManagement 项目的缺陷跟踪系统信息</li><li>ciManagement 项目的持续集成系统信息</li><li>scm 项目的版本控制系统信息</li><li>mailingLists 项目的邮件列表信息</li><li>properties 自定义的 Maven 属性</li><li>dependencies 项目的依赖配置</li><li>dependencyManagement 项目的依赖管理配置</li><li>repositories 项目的仓库配置</li><li>build 项目源码目录配置、输出目录配置、插件配置、插件管理配置等</li><li>reporting 项目的报告输出目录配置、报告插件配置</li></ul><h1 id="依赖管理"><a href="#依赖管理" class="headerlink" title="依赖管理"></a>依赖管理</h1><p>上面说到 dependencies 是可以继承的，也就是说父POM中添加的依赖，子项目中也会引入。</p><p>这样一来有一些好处，不过也有一些不好的地方：如果某个子项目继承了这个父POM，但是这个子项目并不需要那么多的依赖，这样岂不是产生了不必要的引用？</p><p>dependencyManagement  的作用就体现出来了，在父POM中使用 dependencyManagement ：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">dependencyManagement</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">dependencies</span>&gt;</span></span><br><span class="line">        <span class="comment">&lt;!-- 随意添加的一个依赖 --&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">dependency</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>org.sonatype.aether<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>aether-parent<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.7<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">dependency</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">dependencies</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">dependencyManagement</span>&gt;</span></span><br></pre></td></tr></table></figure><p>现在的效果是：</p><ul><li>如果子项目中没有添加这个依赖，那么即使继承了父POM，子项目也不会引入这个依赖。</li></ul><p>看起来没什么卵用，因为在子项目中还是要手动的添加依赖，但实际上还是有用的。因为在子项目中添加依赖时，可以省略 <code>version</code>，在父POM中做统一的版本管理，需要修改版本时只需要修改父POM中的 <code>version</code>。</p><h1 id="使用-import"><a href="#使用-import" class="headerlink" title="使用 import"></a>使用 import</h1><p>import 也是依赖范围的一种，只不过在 dependencyManagement  中才有用。</p><p>实际作用是：把上面的 moduleA 中的 dependencyManagement  合并到当前的 POM 的 dependencyManagement  元素中。（当然也可以使用复制、继承的方式实现）</p><p>注意点：</p><ul><li>type 是 pom</li><li>scope 是 import</li></ul><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">dependencyManagement</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">dependencies</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">dependency</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.test.modules<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>moduleA<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.0-SNAPSHOT<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">type</span>&gt;</span>pom<span class="tag">&lt;/<span class="name">type</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">scope</span>&gt;</span>import<span class="tag">&lt;/<span class="name">scope</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">dependency</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">dependencies</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">dependencyManagement</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="插件管理"><a href="#插件管理" class="headerlink" title="插件管理"></a>插件管理</h1><p>插件管理与依赖管理类似，使用 pluginManagement 之后同样是按需引入。</p><p>插件的隐含信息：</p><ul><li>版本。核心插件已经配置了版本</li><li>内置绑定。插件已经绑定了生命周期的阶段</li></ul><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">build</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">pluginManagement</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">plugins</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">plugin</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>org.apache.maven.plugins<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>maven-compiler-plugin<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">configuration</span>&gt;</span></span><br><span class="line">                    <span class="tag">&lt;<span class="name">source</span>&gt;</span>1.5<span class="tag">&lt;/<span class="name">source</span>&gt;</span></span><br><span class="line">                    <span class="tag">&lt;<span class="name">target</span>&gt;</span>1.5<span class="tag">&lt;/<span class="name">target</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;/<span class="name">configuration</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">plugin</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">plugins</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">pluginManagement</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">build</span>&gt;</span></span><br></pre></td></tr></table></figure><p>同样建议在父POM中统一管理插件的版本。</p><h1 id="超级POM"><a href="#超级POM" class="headerlink" title="超级POM"></a>超级POM</h1><p>超级POM类似于 Java 的 Object 类，是所有类的基类。</p><p>Maven 项目中的 pom.xml 还可以自定义源码目录，但是不建议这么做，最好是按照约定来开发。</p><p>现在只需要知道有超级POM的存在，并且所有 pom.xml 都继承自它，所以有很多配置不用我们自己书写，就可以直接使用。</p><h1 id="反应堆"><a href="#反应堆" class="headerlink" title="反应堆"></a>反应堆</h1><p>反应堆这个翻译有点难以理解，大概可以理解成：多个存在聚合关系的项目在构建时，Maven 需要解读构建的顺序，解读得到的结构顺序称为反应堆。</p><p>比如 moduleA 是聚合模块，moduleB、moduleC 是普通模块，同时这两个模块继承自 moduleD。</p><p>假设 moduleA 中模块的声明顺序是：</p><p>moduleB -&gt; moduleC -&gt; moduleD</p><p>在构建过程的，Maven 得到的反应堆是 moduleD -&gt; moduleB -&gt; moduleC。</p><p>这是因为从上往下构建，发现某个模块依赖于另一个模块，那么 Maven 将会先构建被依赖的模块，也就是这里的 moduleD。</p><p>另外，moduleC 也依赖于 moduleD，但是由于 moduleD 已经被构建，所以直接构建 moduleC。</p><h1 id="裁剪反应堆"><a href="#裁剪反应堆" class="headerlink" title="裁剪反应堆"></a>裁剪反应堆</h1><p>对于一个聚合项目，有时可能只需要构建一部分的模块，而不是完整的反应堆。</p><p>Maven 的命令行选项：</p><ul><li>-am，–also-make 同时构建所列模块的依赖模块</li><li>-amd，-also-make-dependents 同时构建依赖于所列模块的模块（谁依赖我，就构建谁）</li><li>-pl， –projects \&lt;arg> 只构建指定的模块，模块间用逗号隔开</li><li>-rf，-resume-from 从指定模块开始往下构建反应堆</li></ul><p>这些选项还可以组合使用，由于理解不深，不举例了。</p><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>多模块开发必须使用聚合。</p><p>使用继承可以简化项目的依赖和插件配置。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;聚合是为了方便的构建多个项目，继承是为了简化 POM 的重复配置。&lt;/p&gt;
    
    </summary>
    
      <category term="Maven" scheme="/categories/Maven/"/>
    
    
  </entry>
  
  <entry>
    <title>Maven 生命周期与插件</title>
    <link href="/2019/02/articles/Maven%20%E7%94%9F%E5%91%BD%E5%91%A8%E6%9C%9F%E4%B8%8E%E6%8F%92%E4%BB%B6/"/>
    <id>/2019/02/articles/Maven 生命周期与插件/</id>
    <published>2019-02-09T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.929Z</updated>
    
    <content type="html"><![CDATA[<p>生命周期是对项目进行的一系列操作，插件用来完成这些操作。</p><a id="more"></a><h1 id="概述"><a href="#概述" class="headerlink" title="概述"></a>概述</h1><p>构建一个项目包括：清理文件 -&gt; 编译 -&gt; 测试 -&gt; 部署。</p><p>因为每一个项目都要进行类似的操作，所以 Maven 抽象出了<strong>生命周期</strong>。</p><p>光是存在生命周期并没有什么意义，而且生命周期<strong>只是定义了</strong>一系列操作，所以在实际的使用中，需要对项目进行某个具体的操作时，将由某个插件来完成这项任务。</p><p>抽象<strong>生命周期</strong>的好处是：制定了规范，只要遵守规范 Maven 就可以自动帮我们完成很多事情。</p><p><strong>抽象</strong>生命周期的好处是：便于拓展。</p><h1 id="三套生命周期"><a href="#三套生命周期" class="headerlink" title="三套生命周期"></a>三套生命周期</h1><p>三套生命周期包括：clean、default、site，每个生命周期又包括多个阶段。</p><p>后一个阶段需要前一个阶段先完成。比如执行第 3 个阶段，Maven 会先执行前面第 1、2 个阶段。</p><h2 id="clean-生命周期"><a href="#clean-生命周期" class="headerlink" title="clean 生命周期"></a>clean 生命周期</h2><p>clean 生命周期的目的是清理项目，它包括三个阶段：</p><ul><li>pre-clean 执行一些清理前需要完成的工作</li><li>clean 清理上一次构建生成的文件</li><li>post-clean 执行一些清理后需要完成的工作</li></ul><h2 id="default-生命周期"><a href="#default-生命周期" class="headerlink" title="default 生命周期"></a>default 生命周期</h2><p>default 生命周期是真正构建时需要执行的，比如编译就是在这个生命周期里面的。</p><p>话说回来，为什么要有三个生命周期呢？我自己的理解是：构建项目时需要执行的任务在 default 生命周期里，但是清理文件这一工作并不是每一次都要执行的，或者是说，清理文件这件事是和编译、打包项目相独立的。所以，他们分为了两个生命周期。site 生命周期同理。逻辑上独立生命周期可以方便理解，实际中使用中，独立生命周期也有好处，比如不是当这一次不需要清理文件时，就不需要加 <code>clean</code> 命令。</p><p>default 生命周期所包括的阶段：</p><ul><li>validate</li><li>initialize</li><li>generate-sources</li><li>process-sources 处理项目主资源文件。一般来说，是对 src/main/resources 目录的内容进行变量替换等工作后，复制到项目输出的主 classpath 目录中。</li><li>generate-resources</li><li>process-resources</li><li>compile 编译项目的主源码。一般来说，是编译 src/main/java 目录下的 Java 文件至项目输出的主 classpath 目录中。</li><li>process-classes</li><li>generate-test-sources</li><li>process-test-sources</li><li>generate-test-resources</li><li>process-test-resources</li><li>test-compile 编译项目的测试代码。一般来说，是编译 src/test/java 目录下的 Java 文件至项目输出的测试 classpath 目录中</li><li>process-test-classes</li><li>test 使用单元测试框架运行测试，测试代码不会被打包或部署。</li><li>prepare-package</li><li>package 接受编译好的代码，打包成可发布的格式，如 JAR</li><li>pre-integration-test</li><li>integration-test</li><li>post-integration-test</li><li>verify</li><li>install 将包安装到 Maven 本地仓库，供本地其他 Maven 项目使用。</li><li>deploy 将最终的包复制到远程仓库，供其他开发人员和 Maven 使用。</li></ul><p><a href="http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html" target="_blank" rel="noopener">官方解释</a></p><h2 id="site-生命周期"><a href="#site-生命周期" class="headerlink" title="site 生命周期"></a>site 生命周期</h2><p>site 生命周期的目的是建立和发布项目站点，Maven 能够基于 POM 所包含的信息，自动生成一个友好的站点，方便团队交流和发布项目信息。</p><p>site 生命周期所包含的阶段：</p><ul><li>pre-site 执行一些在生成项目站点之前需要完成的工作</li><li>site 生成项目站点文档</li><li>post-site 执行一些在生成项目站点之后需要完成的工作</li><li>site-deploy 将生成的项目站点发布到服务器生</li></ul><h1 id="命令行与生命周期"><a href="#命令行与生命周期" class="headerlink" title="命令行与生命周期"></a>命令行与生命周期</h1><ul><li>命令 <code>mvn clean</code> 调用 clean 生命周期的 clean 阶段。实际执行的是 clean 生命周期的 pre-clean 和 clean 阶段。也就是说，调用某个阶段，之前的阶段都会被调用。</li><li>命令 <code>mvn clean install</code> 实际执行的是 clean 生命周期的 pre-clean、clean 阶段，以及 default 生命周期的从 validate 至 install 的所有阶段。</li></ul><h1 id="插件目标"><a href="#插件目标" class="headerlink" title="插件目标"></a>插件目标</h1><p>前面说了，生命周期只是定义了规范，具体执行某一项操作是通过插件来完成的。</p><p>有些操作会比较相似，这样也就有一些代码可以复用。</p><p>现在的问题是：如果每一项任务都对应一个插件，代码就不好复用，所以这样不可取。</p><p>所以，一个插件有多个目标，一个目标用来执行生命周期中的一个任务。</p><h1 id="插件绑定"><a href="#插件绑定" class="headerlink" title="插件绑定"></a>插件绑定</h1><p>Maven 抽象出了生命周期，假设现在也有了插件，但是它们两者似乎并没有任何关系。</p><p>所以就需要插件绑定，将二者联系起来。</p><h2 id="内置绑定"><a href="#内置绑定" class="headerlink" title="内置绑定"></a>内置绑定</h2><p>Maven 为一些<strong>生命周期阶段</strong>绑定了插件的目标。</p><p>比如 default 生命周期的 compile 阶段跟 maven-compiler-plugin 插件的 compile 目标绑定了。</p><h2 id="自定义绑定"><a href="#自定义绑定" class="headerlink" title="自定义绑定"></a>自定义绑定</h2><p>有时候我们需要执行某项任务，但是并没有内置绑定插件目标来实现它。</p><p>此时就需要自定义绑定插件来完成。</p><p>这里需要注意的是 <code>executions</code> 元素，它下面的每一个 <code>execution</code> 子元素用来配置一个任务。</p><p>其中 <code>phrase</code> 指的是生命周期的某一个阶段，<code>goal</code> 指的是插件的某一个目标。</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">build</span>&gt;</span></span><br><span class="line">   <span class="tag">&lt;<span class="name">plugin</span>&gt;</span></span><br><span class="line">       <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>org.apache.maven<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">       <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>maven-source-plugin<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">       <span class="tag">&lt;<span class="name">version</span>&gt;</span>2.1.1<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">       <span class="tag">&lt;<span class="name">executions</span>&gt;</span></span><br><span class="line">         <span class="tag">&lt;<span class="name">execution</span>&gt;</span></span><br><span class="line">           <span class="tag">&lt;<span class="name">id</span>&gt;</span>id<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">           <span class="tag">&lt;<span class="name">phase</span>&gt;</span>verify<span class="tag">&lt;/<span class="name">phase</span>&gt;</span></span><br><span class="line">           <span class="tag">&lt;<span class="name">goals</span>&gt;</span></span><br><span class="line">             <span class="tag">&lt;<span class="name">goal</span>&gt;</span>java<span class="tag">&lt;/<span class="name">goal</span>&gt;</span></span><br><span class="line">           <span class="tag">&lt;/<span class="name">goals</span>&gt;</span></span><br><span class="line">         <span class="tag">&lt;/<span class="name">execution</span>&gt;</span></span><br><span class="line">       <span class="tag">&lt;/<span class="name">executions</span>&gt;</span></span><br><span class="line"> <span class="tag">&lt;/<span class="name">plugin</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">build</span>&gt;</span></span><br></pre></td></tr></table></figure><p>如果没有 <code>phase</code> 标签，也不过出错。这是因为很多插件的目标在编写时已经定义了默认的绑定阶段，所以这里可以不写。</p><h2 id="查看插件信息"><a href="#查看插件信息" class="headerlink" title="查看插件信息"></a>查看插件信息</h2><p>使用下面这条命令：</p><p>（如果省略了版本信息，Maven 将自动获取最新版本来进行表述）</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn help:describe -Dplugin=org.apache.maven.plugins:maven-source-plugin:2.1.1 -Ddetail</span><br></pre></td></tr></table></figure><p>查看默认绑定阶段：<code>Bound to phase:</code></p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">...</span><br><span class="line">  Implementation: org.apache.maven.plugin.source.TestSourceJarNoForkMojo</span><br><span class="line">  Language: java</span><br><span class="line">  Bound to phase: package</span><br><span class="line"></span><br><span class="line">...</span><br></pre></td></tr></table></figure><h3 id="使用前缀"><a href="#使用前缀" class="headerlink" title="使用前缀"></a>使用前缀</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn help:describe -Dplugin=compiler</span><br></pre></td></tr></table></figure><h3 id="指定插件目标"><a href="#指定插件目标" class="headerlink" title="指定插件目标"></a>指定插件目标</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn help:describe -Dplugin=compiler -Dgoal=compile</span><br></pre></td></tr></table></figure><h3 id="输出更详细的信息"><a href="#输出更详细的信息" class="headerlink" title="输出更详细的信息"></a>输出更详细的信息</h3><p>加了 <code>-Ddetail</code>，将插件目标读取的属性列出。</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn help:describe -Dplugin=compiler -Dgoal=compile -Ddetail</span><br></pre></td></tr></table></figure><h1 id="插件配置"><a href="#插件配置" class="headerlink" title="插件配置"></a>插件配置</h1><h2 id="命令行插件配置"><a href="#命令行插件配置" class="headerlink" title="命令行插件配置"></a>命令行插件配置</h2><p>用户可以在 Maven 命令中使用 -D 参数，并伴随一个参数建=参数值的形式，来配置插件目标的参数。</p><p>例如：maven-surefire-plugin 提供了一个 maven.test.skip 参数，当其值为 true 时，将会跳过测试。</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn install -Dmaven.test.skip=true</span><br></pre></td></tr></table></figure><p>参数 -D 是 Java 自带的，其功能是通过命令行设置一个 Java 系统属性，Maven 会在需要时读取该属性的值，实现插件参数的配置。</p><h2 id="pom-中插件全局配置"><a href="#pom-中插件全局配置" class="headerlink" title="pom 中插件全局配置"></a>pom 中插件全局配置</h2><p>例如，为 maven-compiler-plugin 插件配置：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">plugins</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">plugin</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>org.apache.maven.plugins<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>maven-compiler-plugin<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">version</span>&gt;</span>3.8.0<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">configuration</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">source</span>&gt;</span>1.8<span class="tag">&lt;/<span class="name">source</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">target</span>&gt;</span>1.8<span class="tag">&lt;/<span class="name">target</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">configuration</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">plugin</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">plugins</span>&gt;</span></span><br></pre></td></tr></table></figure><h2 id="pom-中插件任务配置"><a href="#pom-中插件任务配置" class="headerlink" title="pom 中插件任务配置"></a>pom 中插件任务配置</h2><p>例子：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">project</span>&gt;</span></span><br><span class="line">  [...]</span><br><span class="line">  <span class="tag">&lt;<span class="name">build</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">plugins</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">plugin</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>maven-antrun-plugin<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.8<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">executions</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">execution</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">phase</span>&gt;</span> <span class="comment">&lt;!-- a lifecycle phase --&gt;</span> <span class="tag">&lt;/<span class="name">phase</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">configuration</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">tasks</span>&gt;</span></span><br><span class="line">                <span class="tag">&lt;<span class="name">echo</span>&gt;</span>xxxxxx<span class="tag">&lt;/<span class="name">echo</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">tasks</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">configuration</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">goals</span>&gt;</span></span><br><span class="line">              <span class="tag">&lt;<span class="name">goal</span>&gt;</span>run<span class="tag">&lt;/<span class="name">goal</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;/<span class="name">goals</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;/<span class="name">execution</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">executions</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">plugin</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">plugins</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;/<span class="name">build</span>&gt;</span></span><br><span class="line">  [...]</span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="从命令行调用插件"><a href="#从命令行调用插件" class="headerlink" title="从命令行调用插件"></a>从命令行调用插件</h1><p>之前执行的命令，比如：<code>mvn install</code> 是执行生命周期中的某一个阶段。</p><p>但是 Maven 也支持直接执行执行插件的某个目标，比如：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mvn dependency:tree</span><br></pre></td></tr></table></figure><h1 id="插件解析机制"><a href="#插件解析机制" class="headerlink" title="插件解析机制"></a>插件解析机制</h1><p>刚说了从命令行调用插件的某个目标，但是话说回来，Maven 定义一个插件，应该也是使用坐标的，为什么 Maven 可以识别上面的 <code>dependency</code> 呢？</p><p>下面慢慢说。</p><h2 id="插件仓库"><a href="#插件仓库" class="headerlink" title="插件仓库"></a>插件仓库</h2><p>如果在本地找不到插件的话，将会到远程仓库查找。</p><p>这跟查找依赖的方式很像，但是查找依赖的远程仓库跟查找插件的远程仓库是不一样的，它们的配置方式也是不一样的。</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">project</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line">  <span class="tag">&lt;<span class="name">pluginRepositories</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">pluginRepository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>apache.snapshots<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>http://repository.apache.org/snapshots/<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">      <span class="comment">&lt;!-- The releases element here is due to an issue in Maven 2.0 that will be</span></span><br><span class="line"><span class="comment">           fixed in future releases. This should be able to be disabled altogether. --&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">releases</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">updatePolicy</span>&gt;</span>daily<span class="tag">&lt;/<span class="name">updatePolicy</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">releases</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">snapshots</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">updatePolicy</span>&gt;</span>daily<span class="tag">&lt;/<span class="name">updatePolicy</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">snapshots</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">pluginRepository</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;/<span class="name">pluginRepositories</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><p>或</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line">  <span class="tag">&lt;<span class="name">profiles</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">profile</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>apache<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">pluginRepositories</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;<span class="name">pluginRepository</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">id</span>&gt;</span>apache.snapshots<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">name</span>&gt;</span>Maven Plugin Snapshots<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">url</span>&gt;</span>http://repository.apache.org/snapshots/<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">releases</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">enabled</span>&gt;</span>false<span class="tag">&lt;/<span class="name">enabled</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;/<span class="name">releases</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">snapshots</span>&gt;</span></span><br><span class="line">            <span class="tag">&lt;<span class="name">enabled</span>&gt;</span>true<span class="tag">&lt;/<span class="name">enabled</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;/<span class="name">snapshots</span>&gt;</span></span><br><span class="line">        <span class="tag">&lt;/<span class="name">pluginRepository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">pluginRepositories</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">profile</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;/<span class="name">profiles</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure><h2 id="插件的默认-groupId"><a href="#插件的默认-groupId" class="headerlink" title="插件的默认 groupId"></a>插件的默认 groupId</h2><p>如果是官方插件（即如果其 groupId 是 org.apache.maven.plugins）就可以省略 groupId 配置，但是不推荐省略，免得别人不理解看不出来。</p><h2 id="解析插件版本"><a href="#解析插件版本" class="headerlink" title="解析插件版本"></a>解析插件版本</h2><ul><li>对于核心插件，Maven 的超级 POM 中设置了版本。因此，即使用户不加任何配置，它们的版本就确定了。</li><li>对于非核心插件，又没有指定版本，Maven 将会检查所有仓库中的可用版本，然后做出选择。</li></ul><p>建议指定一个明确的版本。</p><h2 id="解析插件前缀"><a href="#解析插件前缀" class="headerlink" title="解析插件前缀"></a>解析插件前缀</h2><p><code>~\.m2\repository\org\apache\maven\plugins\maven-metadata.xml</code> 和 <code>~\.m2\repository\org\codehaus\mojo\maven-metadata.xml</code> 存储了插件和前缀的对应关系。</p><p>随便举个例子：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">plugin</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">name</span>&gt;</span>Appfuse Maven Plugin<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">prefix</span>&gt;</span>appfuse<span class="tag">&lt;/<span class="name">prefix</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>appfuse-maven-plugin<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">plugin</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>原来生命周期不仅仅是 <code>clean</code>、<code>install</code> …，而且生命周期分为三套。</p><p>原来插件是生命周期的具体实现，原来插件目标是与生命周期的某个阶段相绑定的。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;生命周期是对项目进行的一系列操作，插件用来完成这些操作。&lt;/p&gt;
    
    </summary>
    
      <category term="Maven" scheme="/categories/Maven/"/>
    
    
  </entry>
  
  <entry>
    <title>Maven 仓库</title>
    <link href="/2019/02/articles/Maven%20%E4%BB%93%E5%BA%93/"/>
    <id>/2019/02/articles/Maven 仓库/</id>
    <published>2019-02-07T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.928Z</updated>
    
    <content type="html"><![CDATA[<p>了解 Maven 中的仓库。</p><a id="more"></a><h1 id="使用-Maven-添加依赖"><a href="#使用-Maven-添加依赖" class="headerlink" title="使用 Maven 添加依赖"></a>使用 Maven 添加依赖</h1><p>一般来说，要在 Java 中使用别人的写好的代码，通常是下载别人提供的 jar 包，然后引入当前的项目来使用。</p><p>这么做的问题是：</p><ul><li>需要手动下载 jar 包</li><li>可能这个 jar 包又依赖于其他的 jar 包</li><li>…</li></ul><p>而在 Maven 中一切都变得很简单，创建一个 Maven 项目之后，假设我们需要使用 okhttp，只需要在谷歌搜索 okhttp，复制下面这段代码到我们的 pom.xml 中即可。</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">dependency</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.squareup.okhttp3<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>okhttp<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">version</span>&gt;</span>3.13.1<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">dependency</span>&gt;</span></span><br></pre></td></tr></table></figure><p>当然了，实际上还是需要下载 jar 包的，毕竟“存在”才可以“使用”，不过这些工作不需要我们来完成。</p><p>在 pom.xml 添加 okhttp 的依赖之后，Maven 会替我们解决依赖的问题，并下载需要的 jar 包。</p><h1 id="Maven-背后的工作"><a href="#Maven-背后的工作" class="headerlink" title="Maven 背后的工作"></a>Maven 背后的工作</h1><p>我们只是告诉 Maven 需要 okhttp 这个依赖，然后呢？Maven 会去哪里下载这个依赖呢？</p><p>实际上 Maven 中有一个默认的地址，它默认就会去那里寻找 jar 包。</p><p>不过，暂时不关心如何查找，先关心在我们电脑中发生的事情。</p><p>Maven 下载 jar 包之后，统一保存到 <code>~/.m2/repository</code> 目录下，这个目录称为本地仓库。</p><h1 id="仓库的概念"><a href="#仓库的概念" class="headerlink" title="仓库的概念"></a>仓库的概念</h1><p>我认为仓库其实就是一个文件夹而已。仓库中存在文件，实际上就是文件夹中存放了一大堆 jar 包（也存在其他文件，<strong>我总是说 jar 包是因为我对其他类型文件用得比较少，认识不深</strong>）。</p><h1 id="仓库的规范（布局）"><a href="#仓库的规范（布局）" class="headerlink" title="仓库的规范（布局）"></a>仓库的规范（布局）</h1><p>为了更好的管理这些 jar 包，仓库有一套规范。否则，假设所有 jar 包都存在一个文件夹中，当 jar 包文件特别多时，查找就需要花很多的时间。（规范的作用还有很多，我还体会不到）</p><p>那么这套规范（或者是说布局）是什么？</p><p>简单说来，就是对于每一个 Maven 项目所构建的文件，就好比一个 jar 包，都在仓库中有一个明确且独立的位置。换句话说，根据一个 Maven 项目的坐标，就可以确定这个项目所生成的 jar 包的位置。</p><p>比如：</p><p>项目坐标：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.diaolizhi<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>tieba-tool<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">version</span>&gt;</span>1.3-SNAPSHOT<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br></pre></td></tr></table></figure><p>实际的文件路径：</p><p><code>C:\Users\xxx\.m2\repository\com\diaolizhi\tieba-tool\1.3-SNAPSHOT</code></p><p>由此可知，<strong>大致</strong>的对应关系是：</p><p><code>groupId/artifactId/version/artifactId-version.packaging</code></p><p><strong>实际上，仓库的规范（布局）不仅仅是根据上面的 groupId、artifactId 和 version，这里只是举个例子。</strong></p><h1 id="仓库的分类"><a href="#仓库的分类" class="headerlink" title="仓库的分类"></a>仓库的分类</h1><ul><li>仓库<ul><li>本地仓库</li><li>远程仓库<ul><li>中央仓库</li><li>私服</li><li>其他公共库</li></ul></li></ul></li></ul><h1 id="本地仓库"><a href="#本地仓库" class="headerlink" title="本地仓库"></a>本地仓库</h1><p>就是默认的 <code>~/.m2/repository</code> 那么目录而已。</p><h2 id="修改本地仓库的位置"><a href="#修改本地仓库的位置" class="headerlink" title="修改本地仓库的位置"></a>修改本地仓库的位置</h2><p>编辑 <code>~/.m2/setting.xml</code> 文件。（先从 Maven 的安装目录将该文件复制过来）</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">localRepository</span>&gt;</span>D:\java\repository<span class="tag">&lt;/<span class="name">localRepository</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="中央仓库"><a href="#中央仓库" class="headerlink" title="中央仓库"></a>中央仓库</h1><p>可以看成一台服务器，上面存放了非常多的 Maven 项目。</p><p>当本地仓库找不到某个依赖时，就会到中央仓库去寻找。</p><h1 id="私服"><a href="#私服" class="headerlink" title="私服"></a>私服</h1><p>架设在局域网的仓库服务。</p><p>特点：</p><ul><li>当 Maven 需要下载时，会向私服发送请求</li><li>如果私服不存在该文件，就向外部的远程仓库请求，并且缓存到私服上，以供下一次使用</li><li>从本地上传文件到私服上供局域网内用户使用</li></ul><h1 id="配置远程仓库"><a href="#配置远程仓库" class="headerlink" title="配置远程仓库"></a>配置远程仓库</h1><p><a href="https://maven.apache.org/guides/mini/guide-multiple-repositories.html" target="_blank" rel="noopener">官方文档 - Setting up Multiple Repositories</a></p><p>修改 pom.xml：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">project</span>&gt;</span></span><br><span class="line">...</span><br><span class="line">  <span class="tag">&lt;<span class="name">repositories</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">repository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>my-repo1<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">name</span>&gt;</span>your custom repo<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>http://jarsm2.dyndns.dk<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">releases</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">enabled</span>&gt;</span>true<span class="tag">&lt;/<span class="name">enabled</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">updatePolicy</span>&gt;</span>daily<span class="tag">&lt;/<span class="name">updatePolicy</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">checksumPolicy</span>&gt;</span>ignore<span class="tag">&lt;/<span class="name">checksumPolicy</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">releases</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">snapshots</span>&gt;</span></span><br><span class="line">          <span class="tag">&lt;<span class="name">enabled</span>&gt;</span>false<span class="tag">&lt;/<span class="name">enabled</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;/<span class="name">snapshots</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">layout</span>&gt;</span>default<span class="tag">&lt;/<span class="name">layout</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">repository</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">repository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>my-repo2<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">name</span>&gt;</span>your custom repo<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>http://jarsm2.dyndns.dk<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">repository</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;/<span class="name">repositories</span>&gt;</span></span><br><span class="line">...</span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><ul><li>id 用来声明一个远程仓库<ul><li>如果 id 设置为 central 将会覆盖中央仓库的配置</li></ul></li><li>name 是远程仓库的名字，用来给人看的</li><li>url 表示远程仓库的地址</li><li>releases 对应发行版本，snapshots 对应快照版本<ul><li>enabled 表示是否对发行版本/快照版本进行下载<ul><li>根据上面的配置：从远程仓库下载发行版本，但是不会下载快照版本</li></ul></li><li>updatePolicy 配置从远程仓库检查更新的频率<ul><li>daily 每天检查一次</li><li>never 从不</li><li>always 每次构建时更新</li><li>interval: X 每个 X 分钟检查更新一次（X 为任意整数）</li></ul></li><li>checksumPolicy 配置 Maven 检查校验和文件的策略<ul><li>默认值 warn 校验失败输出警告信息</li><li>fail 校验失败就让构建失败</li><li>ignore 完全忽略校验和错误</li></ul></li></ul></li></ul><h1 id="远程仓库的认证"><a href="#远程仓库的认证" class="headerlink" title="远程仓库的认证"></a>远程仓库的认证</h1><p><a href="https://maven.apache.org/guides/mini/guide-encryption.html" target="_blank" rel="noopener">参考文档</a></p><p>修改 settings.xml：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">...</span><br><span class="line">  <span class="tag">&lt;<span class="name">servers</span>&gt;</span></span><br><span class="line">...</span><br><span class="line">    <span class="tag">&lt;<span class="name">server</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>my-proj<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">username</span>&gt;</span>repo-user<span class="tag">&lt;/<span class="name">username</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">password</span>&gt;</span>repo-pwd<span class="tag">&lt;/<span class="name">password</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">server</span>&gt;</span></span><br><span class="line">...</span><br><span class="line">  <span class="tag">&lt;/<span class="name">servers</span>&gt;</span></span><br><span class="line">...</span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure><p>远程仓库是在 pom.xml 中配置的，而认证是在 settings.xml 中配置的。</p><p>这么做也是很好理解的，如果账号密码写在 Maven 项目中，那么这个项目发给别人的时候就可能造成账号的泄漏，所以写在本地的 settings.xml 是相对安全的。</p><p>另外需要注意，这里的 <code>id</code> 和 pom.xml 中配置的远程仓库的 <code>id</code> 需要对应起来。</p><h1 id="部署至远程仓库"><a href="#部署至远程仓库" class="headerlink" title="部署至远程仓库"></a>部署至远程仓库</h1><p><a href="https://maven.apache.org/pom.html#Distribution_Management" target="_blank" rel="noopener">参考文档</a></p><p>在 settings.xml 中添加：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">project</span> <span class="attr">xmlns</span>=<span class="string">"http://maven.apache.org/POM/4.0.0"</span></span></span><br><span class="line"><span class="tag">  <span class="attr">xmlns:xsi</span>=<span class="string">"http://www.w3.org/2001/XMLSchema-instance"</span></span></span><br><span class="line"><span class="tag">  <span class="attr">xsi:schemaLocation</span>=<span class="string">"http://maven.apache.org/POM/4.0.0</span></span></span><br><span class="line"><span class="tag"><span class="string">                      https://maven.apache.org/xsd/maven-4.0.0.xsd"</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line">  <span class="tag">&lt;<span class="name">distributionManagement</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">repository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>corp1<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">name</span>&gt;</span>Corporate Repository<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>scp://repo/maven2<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">repository</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">snapshotRepository</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>propSnap<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">name</span>&gt;</span>Propellors Snapshots<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>sftp://propellers.net/maven<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">snapshotRepository</span>&gt;</span></span><br><span class="line">    ...</span><br><span class="line">  <span class="tag">&lt;/<span class="name">distributionManagement</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><p><code>distributionManagement</code> 包括两个子元素： <code>repository</code>、<code>snapshotRepository</code>，分别对应发布版本的仓库和快照版本的仓库。</p><p><strong>上面的配置是在 settings.xml 中的，当执行 <code>mvn clean deploy</code> 时，会判断当前项目是发布版本还是快照版本，部署到对应的远程仓库中。</strong></p><h1 id="快照版本"><a href="#快照版本" class="headerlink" title="快照版本"></a>快照版本</h1><p>一个人写项目的时候体现不出快照版本的好处，当两个人合作的时候就体现出来了。</p><p>小明开发项目 A，小红开发项目 B。项目 B 依赖于项目 A，并且项目 A 正在开发。</p><p>怎么保证小红时刻可以获取到最新的项目 A 呢？</p><ul><li>每次下载源码进行编译。这显然不合理，不仅浪费时间，而且编译出错也不好解决。</li><li>项目 A 部署时修改版本号。这可以，但是有些麻烦，每次上传需要修改版本号，下载也需要修改版本号。</li><li>使用快照。上传和下载时都使用： x.y-SNAPSHOT。这样做的神奇之处在于，上传到远程仓库时，名字不是 x.y-SNAPSHOT 而是 x.y-时间戳。另一方面，需要下载最新版本的项目 A 时，Maven 会检查远程仓库是否有更新，如果有就下载。<ul><li>什么时候会下载最新版本的项目 A 呢？<ul><li>根据上面提到的 updatePolicy，默认每天更新一次</li><li>或者使用 <code>mvn clean install-U</code></li></ul></li></ul></li></ul><h1 id="解析依赖的机制"><a href="#解析依赖的机制" class="headerlink" title="解析依赖的机制"></a>解析依赖的机制</h1><p>当我们在 pom.xml 中添加依赖的时候，Maven 是如何判断从哪里得到这个依赖的呢？</p><ul><li>如果依赖的范围是 system，直接从本地文件系统解析该文件，找到就结束</li><li>根据依赖计算仓库路径，尝试在本地仓库查找该文件，找到就结束</li><li>上面两种方式都找不到时，如果依赖的版本号是确定的，比如 1.2、2.1-beta-1，将遍历所有远程仓库，发现后就下载，然后结束</li><li>如果版本号指定的是 RELEASE 或者 LATEST 或者 SNAPSHOT，Maven 会根据更新策略，访问远程仓库的元数据：<code>groupId/artifactId/maven-metadata.xml</code>，将其与本地仓库的元数据合并后，计算出真实的版本号，然后在从本地仓库或者远程仓库中查找。</li></ul><p>注意点：</p><ul><li>快照版本在远程仓库中带时间戳，但是从远程仓库下载之后时间戳又变成了 SNAPSHOT。</li><li>RELEASE 表示最新的发布版本，LATEST 表示最新版本（包括快照版本）</li><li>不要使用 RELEASE 和  LATEST </li></ul><h1 id="镜像"><a href="#镜像" class="headerlink" title="镜像"></a>镜像</h1><p>修改 settings.xml：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">settings</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line">  <span class="tag">&lt;<span class="name">mirrors</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;<span class="name">mirror</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">id</span>&gt;</span>UK<span class="tag">&lt;/<span class="name">id</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">name</span>&gt;</span>UK Central<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">url</span>&gt;</span>http://uk.maven.org/maven2<span class="tag">&lt;/<span class="name">url</span>&gt;</span></span><br><span class="line">      <span class="tag">&lt;<span class="name">mirrorOf</span>&gt;</span>central<span class="tag">&lt;/<span class="name">mirrorOf</span>&gt;</span></span><br><span class="line">    <span class="tag">&lt;/<span class="name">mirror</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;/<span class="name">mirrors</span>&gt;</span></span><br><span class="line">  ...</span><br><span class="line"><span class="tag">&lt;/<span class="name">settings</span>&gt;</span></span><br></pre></td></tr></table></figure><p><code>mirrorOf</code> 表示这个是哪个仓库的镜像，这里的 <code>central</code> 指的就是中央仓库。</p><p>因为私服可以访问外部仓库，所以直接指定私服作为镜像也是可以的，反正找不到的时候它会向外部寻找。</p><p><code>mirrorOf</code> 中间可以是：</p><ul><li><code>*</code> 匹配所有远程仓库</li><li><code>external: *</code> 匹配所有不在本机上的远程仓库</li><li><code>repo1, repo2</code> 匹配仓库 repo1 和 repo2</li><li><code>*, !repo1</code> 匹配所有远程仓库，repo1 除外</li></ul><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><ul><li>仓库用来存放 Maven 生成的文件，且仓库的目录有自己的规范。</li><li>仓库可以大致分为本地仓库和远程仓库。</li><li>快照是在开发时使用的。</li><li>使用镜像可以加快 Maven 的下载速度。</li></ul>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;了解 Maven 中的仓库。&lt;/p&gt;
    
    </summary>
    
      <category term="Maven" scheme="/categories/Maven/"/>
    
    
  </entry>
  
  <entry>
    <title>创建 Maven 项目</title>
    <link href="/2019/02/articles/Maven%E7%AC%94%E8%AE%B0%20-%20%E5%88%9B%E5%BB%BA%20Maven%20%E9%A1%B9%E7%9B%AE/"/>
    <id>/2019/02/articles/Maven笔记 - 创建 Maven 项目/</id>
    <published>2019-02-07T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.929Z</updated>
    
    <content type="html"><![CDATA[<p>温故知新。</p><a id="more"></a><h1 id="pom-文件"><a href="#pom-文件" class="headerlink" title="pom 文件"></a>pom 文件</h1><p>该文件的作用：</p><ul><li>在茫茫 Java 类库中声明自己的身份</li><li>并且声明需要依赖的类库</li><li>说明项目将怎么样进行构建（比如说明入口文件）</li><li>…</li></ul><h1 id="简单的-pom-xml-示例"><a href="#简单的-pom-xml-示例" class="headerlink" title="简单的 pom.xml 示例"></a>简单的 pom.xml 示例</h1><ul><li>xml 版本、编码方式声明</li><li>project 是根元素</li><li>对于 Maven2 和 Maven3 来说 <code>modelVersion</code> 只能是 4.0.0</li><li>groupId 域名倒序加项目名</li><li>artifactId 模块名</li><li>version 版本</li><li>name 项目的描述</li></ul><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line">&lt;?xml version="1.0" encoding="UTF-8"?&gt;</span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;<span class="name">project</span> <span class="attr">xmlns</span>=<span class="string">"http://maven.apache.org/POM/4.0.0"</span> <span class="attr">xmlns:xsi</span>=<span class="string">"http://www.w3.org/2001/XMLSchema-instance"</span></span></span><br><span class="line"><span class="tag">  <span class="attr">xsi:schemaLocation</span>=<span class="string">"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">modelVersion</span>&gt;</span>4.0.0<span class="tag">&lt;/<span class="name">modelVersion</span>&gt;</span></span><br><span class="line"></span><br><span class="line">  <span class="tag">&lt;<span class="name">groupId</span>&gt;</span>com.diaolizhi.second<span class="tag">&lt;/<span class="name">groupId</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">artifactId</span>&gt;</span>myHelloWorld<span class="tag">&lt;/<span class="name">artifactId</span>&gt;</span></span><br><span class="line">  <span class="tag">&lt;<span class="name">version</span>&gt;</span>1.0-SNAPSHOT<span class="tag">&lt;/<span class="name">version</span>&gt;</span></span><br><span class="line"></span><br><span class="line">  <span class="tag">&lt;<span class="name">name</span>&gt;</span>myHelloWorld<span class="tag">&lt;/<span class="name">name</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">project</span>&gt;</span></span><br></pre></td></tr></table></figure><h1 id="Maven-项目规定"><a href="#Maven-项目规定" class="headerlink" title="Maven 项目规定"></a>Maven 项目规定</h1><ul><li>项目代码放在 <code>/src/main/java/com.xxx.groupId.artifactId</code> 目录下 </li><li>测试代码放在 <code>/src/test/java/com.xxx.groupId.artifactId</code> 目录下</li></ul><h1 id="Maven-输出"><a href="#Maven-输出" class="headerlink" title="Maven 输出"></a>Maven 输出</h1><ul><li>输出内容在 <code>/target/</code> 目录下，包括生成的 jar 包</li><li><code>classes</code> 目录下是编译生成的 class 文件</li></ul><h1 id="指定入口类"><a href="#指定入口类" class="headerlink" title="指定入口类"></a>指定入口类</h1><ul><li>借助 maven-shade-plugin</li></ul><h1 id="mvn-clean"><a href="#mvn-clean" class="headerlink" title="mvn clean"></a>mvn clean</h1><ul><li>删除 target 目录</li></ul><h1 id="mvn-compile"><a href="#mvn-compile" class="headerlink" title="mvn compile"></a>mvn compile</h1><ul><li>编译项目主代码</li></ul><h1 id="mvn-test"><a href="#mvn-test" class="headerlink" title="mvn test"></a>mvn test</h1><ul><li>执行测试用例</li></ul><h1 id="mvn-package"><a href="#mvn-package" class="headerlink" title="mvn package"></a>mvn package</h1><ul><li>打包</li></ul><h1 id="mvn-install"><a href="#mvn-install" class="headerlink" title="mvn install"></a>mvn install</h1><ul><li>打包并添加到本地仓库</li></ul>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;温故知新。&lt;/p&gt;
    
    </summary>
    
      <category term="Maven" scheme="/categories/Maven/"/>
    
    
  </entry>
  
  <entry>
    <title>Maven 相关目录</title>
    <link href="/2019/02/articles/Maven%E7%AC%94%E8%AE%B0%20-%20Maven%20%E7%9B%B8%E5%85%B3%E7%9B%AE%E5%BD%95/"/>
    <id>/2019/02/articles/Maven笔记 - Maven 相关目录/</id>
    <published>2019-02-07T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.929Z</updated>
    
    <content type="html"><![CDATA[<p>对 Maven 的理解及其相关目录。</p><a id="more"></a><h1 id="Maven-是什么"><a href="#Maven-是什么" class="headerlink" title="Maven 是什么"></a>Maven 是什么</h1><p>Maven 是一个构建工具、依赖管理工具。</p><h1 id="什么是构建"><a href="#什么是构建" class="headerlink" title="什么是构建"></a>什么是构建</h1><p>从源代码开始，编译 -&gt; 测试 -&gt; 打包 -&gt; 部署 -&gt; 运行。</p><h1 id="什么是依赖管理"><a href="#什么是依赖管理" class="headerlink" title="什么是依赖管理"></a>什么是依赖管理</h1><p>Maven 使用坐标定位一个依赖包，而且每一个依赖都指定了自己的依赖，不需要我们手动的下载、导入 jar 包，也不需要我们人工的解决包的依赖、以及兼容问题。</p><h1 id="M2-HOME"><a href="#M2-HOME" class="headerlink" title="M2_HOME"></a>M2_HOME</h1><p>在电脑上 M2_HOME 环境变量指向的是 Maven 的安装目录。</p><p>下面介绍该目录下的几个目录：</p><h2 id="bin"><a href="#bin" class="headerlink" title="bin"></a>bin</h2><p>该目录包含了 mvn 运行的脚本。</p><p>当我们在命令行执行 mvn 时，运行的就是这里的 mvn 文件。</p><h2 id="boot"><a href="#boot" class="headerlink" title="boot"></a>boot</h2><p>该目录包含一个类加载器框架。</p><p>对于一般的 Maven 用户不必关心它。</p><h2 id="conf"><a href="#conf" class="headerlink" title="conf"></a>conf</h2><p>该目录包含一个非常重要的 settings.xml 文件。</p><p>直接修改该文件将会在全局范围内改变 Maven 的设置，所以推荐将该文件复制到 <code>~/.m2/</code> 目录中再修改，这样做只对一个用户生效。</p><h2 id="lib"><a href="#lib" class="headerlink" title="lib"></a>lib</h2><p>该目录包含 Maven 运行时需要的 Jar 包，可以说这个目录才是真正的 Maven。</p><h1 id="m2"><a href="#m2" class="headerlink" title="~./m2"></a>~./m2</h1><p>默认情况下，<code>~/.m2</code> 目录下只有一个  repository 目录，这个 repository 包含通过 Maven 下载的 Jar 包。</p><p>另外，推荐将 <code>M2_HOME/conf/settings.xml</code> 复制到这个目录下。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;对 Maven 的理解及其相关目录。&lt;/p&gt;
    
    </summary>
    
      <category term="Maven" scheme="/categories/Maven/"/>
    
    
  </entry>
  
  <entry>
    <title>Shell 脚本自动部署 Spring Boot 项目</title>
    <link href="/2019/01/articles/Shell%20%E8%84%9A%E6%9C%AC%E8%87%AA%E5%8A%A8%E9%83%A8%E7%BD%B2%20Spring%20Boot%20%E9%A1%B9%E7%9B%AE/"/>
    <id>/2019/01/articles/Shell 脚本自动部署 Spring Boot 项目/</id>
    <published>2019-01-12T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.929Z</updated>
    
    <content type="html"><![CDATA[<p>同步代码 -&gt; 打包 -&gt; 终止进程 -&gt; 运行项目<br><a id="more"></a></p><h1 id="准备"><a href="#准备" class="headerlink" title="准备"></a>准备</h1><h2 id="Git"><a href="#Git" class="headerlink" title="Git"></a>Git</h2><p>腾讯云 Linux 主机自带 Git，无需再安装。</p><p>但是需要执行：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">ssh-keygen -t rsa</span><br></pre></td></tr></table></figure><p>并将 ~/.ssh/id_rsa.pub 里的内容复制到 GitHub，这样才可以 git clone 私有项目。</p><h2 id="maven"><a href="#maven" class="headerlink" title="maven"></a>maven</h2><p>maven 用来打包 Spring Boot 项目，下载方式：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">wget http://mirror.bit.edu.cn/apache/maven/maven-3/3.6.0/binaries/apache-maven-3.6.0-bin.tar.gz</span><br></pre></td></tr></table></figure><p>解压：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">tar -zvxf apache-xxxx</span><br></pre></td></tr></table></figure><p>添加到 $PATH 变量：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">vim /etc/profile</span><br></pre></td></tr></table></figure><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">PATH=&quot;$PATH&quot;:/usr/xxxxx</span><br></pre></td></tr></table></figure><h2 id="JDK"><a href="#JDK" class="headerlink" title="JDK"></a>JDK</h2><p>maven 需要 jdk 而不是 jre，否则执行 maven install 时会报错，如果装了 jdk 可以跳过这一步。</p><p>安装命令：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">yum install java-1.8.0-openjdk-devel</span><br></pre></td></tr></table></figure><p>安装之后使用 find 命令找到安装目录，并将其 bin 目录添加到 $PATH 变量中。</p><h1 id="编写脚本"><a href="#编写脚本" class="headerlink" title="编写脚本"></a>编写脚本</h1><h2 id="关键点"><a href="#关键点" class="headerlink" title="关键点"></a>关键点</h2><ul><li>如何终止正在运行的进程</li><li>如何获取到最新生成的 jar 包的文件名</li></ul><h2 id="解决办法"><a href="#解决办法" class="headerlink" title="解决办法"></a>解决办法</h2><ul><li>定义 PRONAME （代表的是项目名）变量，然后通过 pkill 命令根据项目名终止进程。</li></ul><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">pkill -f "java -jar $PRONAME"</span><br></pre></td></tr></table></figure><ul><li>通过 ls 和 tail 命令找到最新生成的 jar 包</li></ul><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">ls -tr $PRONAME*.jar | tail -n 1</span><br></pre></td></tr></table></figure><h2 id="注意点"><a href="#注意点" class="headerlink" title="注意点"></a>注意点</h2><p>需要指定项目的<strong>绝对路径</strong>，因为不确定在哪个目录下执行此脚本，所以就可能导致无法切换到正确的目录，那就会出错。</p><p>另外，如果：</p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">PROPATH='~/xxxxx/xxxxx/xxxx.sh'</span><br></pre></td></tr></table></figure><p>也是无法正确的切换目录的，要把 ~ 替换成 /root</p><h2 id="完整脚本"><a href="#完整脚本" class="headerlink" title="完整脚本"></a>完整脚本</h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#</span><span class="bash"> 项目名</span></span><br><span class="line">PRONAME="demo"</span><br><span class="line"><span class="meta">#</span><span class="bash"> 项目所在路径</span></span><br><span class="line">PROPATH='/root/xxxxx/xxxxx/xxxx.sh'</span><br><span class="line"></span><br><span class="line">nohup git pull origin master &gt;/dev/null 2&gt;&amp;1</span><br><span class="line"></span><br><span class="line">cd $PROPATH</span><br><span class="line"></span><br><span class="line">nohup mvn install -DskipTests &gt;/dev/null 2&gt;&amp;1</span><br><span class="line"></span><br><span class="line">cd target</span><br><span class="line"></span><br><span class="line">FILENAME=`ls -tr $PRONAME*.jar | tail -n 1`</span><br><span class="line"></span><br><span class="line">pkill -f "java -jar $PRONAME"</span><br><span class="line"></span><br><span class="line">nohup java -jar $FILENAME &gt;/dev/null 2&gt;log.txt &amp;</span><br></pre></td></tr></table></figure><h1 id="Java-执行-Shell-脚本"><a href="#Java-执行-Shell-脚本" class="headerlink" title="Java 执行 Shell 脚本"></a>Java 执行 Shell 脚本</h1><p>既然可以通过 Java 执行 Shell 脚本，那么就可以创建一个 Get 接口，当它被调用时就执行上面这个脚本。</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">ReloadSystem</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">reloadSystem</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        ProcessBuilder processBuilder = <span class="keyword">new</span> ProcessBuilder();</span><br><span class="line"></span><br><span class="line">        processBuilder.command(<span class="string">"bash"</span>, <span class="string">"-c"</span>, <span class="string">"bash ~/xxxxx/xxxxx/xxxx.sh"</span>);</span><br><span class="line"></span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line"></span><br><span class="line">            Process process = processBuilder.start();</span><br><span class="line"></span><br><span class="line">            StringBuilder output = <span class="keyword">new</span> StringBuilder();</span><br><span class="line"></span><br><span class="line">            BufferedReader reader = <span class="keyword">new</span> BufferedReader(</span><br><span class="line">                    <span class="keyword">new</span> InputStreamReader(process.getInputStream()));</span><br><span class="line"></span><br><span class="line">            String line;</span><br><span class="line">            <span class="keyword">while</span> ((line = reader.readLine()) != <span class="keyword">null</span>) &#123;</span><br><span class="line">                output.append(line + <span class="string">"\n"</span>);</span><br><span class="line">            &#125;</span><br><span class="line"></span><br><span class="line">            <span class="keyword">int</span> exitVal = process.waitFor();</span><br><span class="line">            <span class="keyword">if</span> (exitVal == <span class="number">0</span>) &#123;</span><br><span class="line">                System.out.println(output);</span><br><span class="line">                <span class="keyword">return</span>;</span><br><span class="line">            &#125; <span class="keyword">else</span> &#123;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (InterruptedException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><ol><li>本地开发，提交到 GitHub</li><li>访问指定接口，执行 Shell 脚本自动完成下面的工作：<ol><li>使用 git pull 同步代码</li><li>使用 mvn install 打包</li><li>终止进程</li><li>使用 java -jar 运行项目</li></ol></li></ol><p>有更好的部署工具，但是现在已经可以满足我的需求了，所以没有动力去学习了。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;同步代码 -&amp;gt; 打包 -&amp;gt; 终止进程 -&amp;gt; 运行项目&lt;br&gt;
    
    </summary>
    
      <category term="Linux" scheme="/categories/Linux/"/>
    
    
  </entry>
  
  <entry>
    <title>GitHub 开放私有仓库</title>
    <link href="/2019/01/articles/GitHub%20%E5%BC%80%E6%94%BE%E7%A7%81%E6%9C%89%E4%BB%93%E5%BA%93/"/>
    <id>/2019/01/articles/GitHub 开放私有仓库/</id>
    <published>2019-01-07T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.923Z</updated>
    
    <content type="html"><![CDATA[<p>喜大普奔，纪念一下。</p><a id="more"></a><p>是时候把自己的垃圾代码设为私有了。</p><p>水一张图片。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/diaolizhi.jpeg" alt></p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;喜大普奔，纪念一下。&lt;/p&gt;
    
    </summary>
    
      <category term="GitHub" scheme="/categories/GitHub/"/>
    
    
  </entry>
  
  <entry>
    <title>Spring Boot 2.x 免费升级 HTTPS</title>
    <link href="/2019/01/articles/Spring%20Boot%20%E5%85%8D%E8%B4%B9%E5%8D%87%E7%BA%A7%20HTTPS/"/>
    <id>/2019/01/articles/Spring Boot 免费升级 HTTPS/</id>
    <published>2019-01-01T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.930Z</updated>
    
    <content type="html"><![CDATA[<p>有个🔒的感觉就是 8 一样嗷。</p><a id="more"></a><p>本文只说操作步骤，别的不讲，因为不会。</p><h1 id="必要的前提"><a href="#必要的前提" class="headerlink" title="必要的前提"></a>必要的前提</h1><ul><li>拥有一个域名</li><li>拥有一个 Linux 服务器</li></ul><h1 id="申请证书"><a href="#申请证书" class="headerlink" title="申请证书"></a>申请证书</h1><p>我是通过 <a href="https://www.youtube.com/watch?v=fL6A9I1-U6M" target="_blank" rel="noopener">Youtube 视频</a> 了解到如何快速免费的申请一个 HTTPS 证书的，推荐大家可以看一哈。</p><p>申请证书的网站是：<a href="https://freessl.cn/" target="_blank" rel="noopener">FreeSSL</a></p><h2 id="进入首页"><a href="#进入首页" class="headerlink" title="进入首页"></a>进入首页</h2><p>需要注意的是：<strong>证书的类型</strong>以及<strong>证书的有效期</strong>，根据个人需要选择。</p><p>我选择的是第二个，因为我需要用到多个二级域名。</p><p>如果只有一个网站，建议选择第一个，因为有效期比较长。</p><p><strong>如果证书到期了，就需要到这个网站再申请一次。</strong></p><p>接下来输入自己的域名，我输入的是：*.ddllzz.xyz</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_15-59-34.png" alt></p><h2 id="创建证书"><a href="#创建证书" class="headerlink" title="创建证书"></a>创建证书</h2><p>直接输入邮箱然后点击创建即可。</p><p><strong>但是为了安全起见，推荐自己生成 CSR，工具自己去网上搜。</strong></p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_16-18-43.png" alt> </p><h2 id="验证"><a href="#验证" class="headerlink" title="验证"></a>验证</h2><p>完成上面一步之后可以看到：</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_16-27-12.png" alt></p><p>此时需要根据上面的提示为自己的域名添加 DNS 解析：</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_16-29-44.png" alt></p><p>等待一会点击上面图中的“配置完成，检测一下”。</p><p>看到下图说明 OK 了。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_16-31-19.png" alt></p><p>再然后点击上图的“点击验证”，得到证书信息：</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_17-44-33.png" alt></p><p>点击下载证书，记得保管好。</p><h1 id="转换"><a href="#转换" class="headerlink" title="转换"></a>转换</h1><p>刚才下载了证书（下载的是一个压缩包），压缩包里的文件是：full_chain.pem 和 private.key，而我们在 Spring Boot 中需要的是 pkcs12 类型的文件，所以需要用 openssl 进行转换。</p><p><strong>推荐在 Linux 下完成转换，因为我在 Windows 下生成的 private.key 一直是 0kb，同样的操作在 Linux 下就没问题。</strong></p><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">openssl pkcs12 -export -in full_chain.pem -inkey private.key -out keystore.p12（这个是生成的文件名） -name tomacat -CAfile full_chain.pem -caname root</span><br></pre></td></tr></table></figure><p>现在得到了 keystore.p12，就可以在 Spring Boot 项目中使用它了。</p><h1 id="配置"><a href="#配置" class="headerlink" title="配置"></a>配置</h1><p>将刚刚得到的 kyestore.p12 文件复制到 Spring Boot 项目中的 resources 目录下，然后在 application.properties 文件中添加：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">server.port=8443</span><br><span class="line">server.ssl.trust-store-type=PKCS12</span><br><span class="line">server.ssl.key-store=classpath:kyestore.p12</span><br><span class="line">server.ssl.key-store-password=这里是进行转换时输入的密码</span><br><span class="line">server.ssl.key-alias=tomcat</span><br></pre></td></tr></table></figure><h1 id="本地测试"><a href="#本地测试" class="headerlink" title="本地测试"></a>本地测试</h1><p>在本地测试时，如果通过 <a href="https://127.0.0.1:8443" target="_blank" rel="noopener">https://127.0.0.1:8443</a> 访问，会提示不安全：</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_17-52-02.png" alt> </p><p>因为刚才的证书是属于 ddllzz.xyz 这个域名的，但是现在并非通过这个域名访问，所以会提示不安全。</p><p>现在修改本机 hosts 文件，添加一行：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">127.0.0.1 ddllzz.xyz</span><br></pre></td></tr></table></figure><p>再次通过 <a href="https://ddllzz.xyz:8443" target="_blank" rel="noopener">https://ddllzz.xyz:8443</a> 访问就行了:</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2019-01-02_17-55-45.png" alt></p><h1 id="80-端口重定向到-HTTPS"><a href="#80-端口重定向到-HTTPS" class="headerlink" title="80 端口重定向到 HTTPS"></a>80 端口重定向到 HTTPS</h1><p>在 Spring Boot 中使用下面这段代码，就可以实现：</p><blockquote><p>当访问 ddllzz.xyz 时跳转到 <a href="https://ddllzz.xyz:8443。" target="_blank" rel="noopener">https://ddllzz.xyz:8443。</a></p></blockquote><p>它存在的意义是：别人可能并不知道你 HTTPS 设置的端口，如果没有这个重定向就无法通过 HTTPS 的方式访问了。</p><p>当然了，设置其他端口重定向到 HTTPS 也是可以的。</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Bean</span></span><br><span class="line"><span class="function"><span class="keyword">public</span> ServletWebServerFactory <span class="title">servletContainer</span><span class="params">()</span> </span>&#123;</span><br><span class="line">    TomcatServletWebServerFactory tomcat = <span class="keyword">new</span> TomcatServletWebServerFactory() &#123;</span><br><span class="line">        <span class="meta">@Override</span></span><br><span class="line">        <span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">postProcessContext</span><span class="params">(Context context)</span> </span>&#123;</span><br><span class="line">            SecurityConstraint securityConstraint = <span class="keyword">new</span> SecurityConstraint();</span><br><span class="line">            securityConstraint.setUserConstraint(<span class="string">"CONFIDENTIAL"</span>);</span><br><span class="line">            SecurityCollection collection = <span class="keyword">new</span> SecurityCollection();</span><br><span class="line">            collection.addPattern(<span class="string">"/*"</span>);</span><br><span class="line">            securityConstraint.addCollection(collection);</span><br><span class="line">            context.addConstraint(securityConstraint);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;;</span><br><span class="line">    tomcat.addAdditionalTomcatConnectors(redirectConnector());</span><br><span class="line">    <span class="keyword">return</span> tomcat;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">private</span> Connector <span class="title">redirectConnector</span><span class="params">()</span> </span>&#123;</span><br><span class="line">    Connector connector = <span class="keyword">new</span> Connector(</span><br><span class="line">        TomcatServletWebServerFactory.DEFAULT_PROTOCOL);</span><br><span class="line">    connector.setScheme(<span class="string">"http"</span>);</span><br><span class="line">    connector.setPort(<span class="number">80</span>);</span><br><span class="line">    connector.setSecure(<span class="keyword">false</span>);</span><br><span class="line">    connector.setRedirectPort(<span class="number">8443</span>);</span><br><span class="line">    <span class="keyword">return</span> connector;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="参考资料"><a href="#参考资料" class="headerlink" title="参考资料"></a>参考资料</h1><p><a href="https://juejin.im/post/5b44b4fef265da0f767530f7" target="_blank" rel="noopener">一文教你将 SpringBoot 网站升级为 HTTPS</a></p><p><a href="https://www.heydari.be/spring-boot-application-secured-by-a-lets-encrypt-certificate/" target="_blank" rel="noopener">Spring Boot Application Secured by Let’s Encrypt Certificate</a></p><p><a href="openssl pkcs12 -export -in crt1 -inkey private.key -out keystore.p12 -name tomcat -CAfile CAcrt -caname root">Spring Boot Secured By Let’s Encrypt</a></p><p><a href="https://github.com/spring-projects/spring-boot/issues/9836" target="_blank" rel="noopener">redirect http to https in Spring boot 2.0.0 M2</a></p><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>终于写完了，写了好几个小时。</p><p>比上午第一次弄还要久，不过总算是搞定了，下次再弄应该就不会那么费劲了。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;有个🔒的感觉就是 8 一样嗷。&lt;/p&gt;
    
    </summary>
    
      <category term="Spring Boot" scheme="/categories/Spring-Boot/"/>
    
    
  </entry>
  
  <entry>
    <title>通过表单上传 Blob 对象</title>
    <link href="/2018/12/articles/%E9%80%9A%E8%BF%87%E8%A1%A8%E5%8D%95%E4%B8%8A%E4%BC%A0%20Blob%20%E5%AF%B9%E8%B1%A1/"/>
    <id>/2018/12/articles/通过表单上传 Blob 对象/</id>
    <published>2018-12-16T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.939Z</updated>
    
    <content type="html"><![CDATA[<p>获取到 Blob 对象之后，如何通过表单提交？</p><a id="more"></a><h1 id="目的"><a href="#目的" class="headerlink" title="目的"></a>目的</h1><p>在 Javascript 中获取到了 Blob 对象，希望将 Blob 对象传递给后端。</p><h1 id="条件"><a href="#条件" class="headerlink" title="条件"></a>条件</h1><p>在 HTML 中有一个 form 表单，form 中有一个可以上传文件的 input 输入框。</p><figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">input</span> <span class="attr">id</span>=<span class="string">"recordInput"</span> <span class="attr">type</span>=<span class="string">"file"</span> <span class="attr">name</span>=<span class="string">"file"</span>&gt;</span></span><br></pre></td></tr></table></figure><p>但是这个输入框只能点击 -&gt; 选择文件，那么如何将 Blob 与输入框联系起来呢？</p><h1 id="解决"><a href="#解决" class="headerlink" title="解决"></a>解决</h1><p>可以直接看这个回答：</p><p><a href="https://stackoverflow.com/questions/50157450/send-blob-object-with-post-form" target="_blank" rel="noopener">Send Blob object with POST Form</a></p><p>首先需要这个方法，它将 File 对象转换成一个 FileList 对象：</p><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">createFileList</span>(<span class="params">a</span>) </span>&#123;</span><br><span class="line">    a = [].slice.call(<span class="built_in">Array</span>.isArray(a) ? a : <span class="built_in">arguments</span>);</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> c, b = c = a.length, d = !<span class="number">0</span>; b-- &amp;&amp; d;) d = a[b] <span class="keyword">instanceof</span> File;</span><br><span class="line">    <span class="keyword">if</span> (!d) <span class="keyword">throw</span> <span class="keyword">new</span> <span class="built_in">TypeError</span>(<span class="string">'expected argument to FileList is File or array of File objects'</span>);</span><br><span class="line">    <span class="keyword">for</span> (b = (<span class="keyword">new</span> ClipboardEvent(<span class="string">''</span>)).clipboardData || <span class="keyword">new</span> DataTransfer; c--;) b.items.add(a[c]);</span><br><span class="line">    <span class="keyword">return</span> b.files;</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure><p>之所以要转换，是因为 input 元素中有一个属性：files，它的类型就是 FileList，必须要转换才可以进行赋值。<em>（注意：并没有 file 这个属性。）</em></p><p>第二步，设置 input 的 files 属性（使用 jQuery 查找元素）：</p><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> recInput = $(<span class="string">"#recordInput"</span>)[<span class="number">0</span>];</span><br><span class="line">recInput.files = createFileList(<span class="keyword">new</span> File([blob], <span class="string">"my-record.mp3"</span>, &#123;<span class="attr">type</span>: <span class="string">"audio/mp3"</span>&#125;));</span><br></pre></td></tr></table></figure><p>这样一来，不用点击选择文件，input 框就已经选中文件了。</p><p><img src="https://md-img-1252869657.cos.ap-shanghai.myqcloud.com/hexo/Snipaste_2018-12-17_22-25-20.png" alt></p><p>后端简略代码：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@RestController</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">IndexController</span> </span>&#123;</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">final</span> String path = <span class="string">"D:\\del\\"</span>;</span><br><span class="line"></span><br><span class="line">    <span class="meta">@PostMapping</span>(<span class="string">"/upload"</span>)</span><br><span class="line">    <span class="function"><span class="keyword">public</span> Object <span class="title">upload</span><span class="params">(@RequestParam(name = <span class="string">"file"</span>)</span> MultipartFile file) </span>&#123;</span><br><span class="line">        System.out.println(file);</span><br><span class="line"></span><br><span class="line">        File file1 = <span class="keyword">new</span> File(path + <span class="string">"aa.mp3"</span>);</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            file.transferTo(file1);</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">return</span> file.getOriginalFilename();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><ul><li>Blob、File、FileList  各自是一种类型，而且 File 是 Blob 的子类。</li><li>查找元素时即使通过 ID 查找，也要使用下标 [0] 选择元素</li></ul>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;获取到 Blob 对象之后，如何通过表单提交？&lt;/p&gt;
    
    </summary>
    
      <category term="Javascript" scheme="/categories/Javascript/"/>
    
    
  </entry>
  
  <entry>
    <title>Centos nginx 配置 https</title>
    <link href="/2018/12/articles/Centos%20nginx%20%E9%85%8D%E7%BD%AE%20https/"/>
    <id>/2018/12/articles/Centos nginx 配置 https/</id>
    <published>2018-12-12T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.923Z</updated>
    
    <content type="html"><![CDATA[<p>在腾讯云主机上给 nginx 配置 https。</p><a id="more"></a><h1 id="前提"><a href="#前提" class="headerlink" title="前提"></a>前提</h1><ul><li>安装了 nginx（在<a href="http://nginx.org/download/" target="_blank" rel="noopener">这里</a>下载 nginx-1.9.9.tar.gz），解压，通过 make 命令安装。</li><li>准备好证书，这里是腾讯云备案送一年的证书。</li><li>为了上传文件方便，下载<a href="https://winscp.net/eng/download.php" target="_blank" rel="noopener">winscp</a>。</li></ul><h1 id="修改-nginx-配置"><a href="#修改-nginx-配置" class="headerlink" title="修改 nginx 配置"></a>修改 nginx 配置</h1><p>进入到 /usr/local/nginx/conf 目录下，修改 nginx.conf，添加一个：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br></pre></td><td class="code"><pre><span class="line">server &#123;</span><br><span class="line">        listen 443;</span><br><span class="line">        server_name diaolizhi.com; #填写绑定证书的域名</span><br><span class="line">        ssl on;</span><br><span class="line">        ssl_certificate 1_diaolizhi.com_bundle.crt;</span><br><span class="line">        ssl_certificate_key 2_diaolizhi.com.key;</span><br><span class="line">        ssl_session_timeout 5m;</span><br><span class="line">        ssl_protocols TLSv1 TLSv1.1 TLSv1.2; #按照这个协议配置</span><br><span class="line">        ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:HIGH:!aNULL:!MD5:!RC4:!DHE;#按照这个套件配置</span><br><span class="line">        ssl_prefer_server_ciphers on;</span><br><span class="line">        location / &#123;</span><br><span class="line">            root   html/record; #站点目录</span><br><span class="line">            index  index.html index.htm;</span><br><span class="line">        &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p><strong>注意：站点目录的 html 前面没有斜杠。</strong></p><h2 id="报错"><a href="#报错" class="headerlink" title="报错"></a>报错</h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">nginx: [emerg] the "ssl" parameter requires ngx_http_ssl_module...</span><br></pre></td></tr></table></figure><p>提示没有 ssl 这个模块，参考博客：<a href="https://www.cnblogs.com/ghjbk/p/6744131.html" target="_blank" rel="noopener">博客园</a></p><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>在 Linux 安装 nginx 之后，可以配置不同的端口，每个端口可以对应 html 目录下的不同的文件夹。</p><p>只要添加一个 server，比如：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line">server &#123;</span><br><span class="line">        listen       8000;</span><br><span class="line">        server_name  localhost;</span><br><span class="line"></span><br><span class="line">        location /&#123;</span><br><span class="line">            root   html/record;</span><br><span class="line">            index  index.html index.htm;</span><br><span class="line">        &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><p>具体用到再百度吧。</p>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;在腾讯云主机上给 nginx 配置 https。&lt;/p&gt;
    
    </summary>
    
      <category term="nginx" scheme="/categories/nginx/"/>
    
    
  </entry>
  
  <entry>
    <title>Spring Boot 集成 Shiro 实现权限控制</title>
    <link href="/2018/12/articles/Spring%20Boot%20%E9%9B%86%E6%88%90%20Shiro%20%E5%AE%9E%E7%8E%B0%E6%9D%83%E9%99%90%E6%8E%A7%E5%88%B6/"/>
    <id>/2018/12/articles/Spring Boot 集成 Shiro 实现权限控制/</id>
    <published>2018-12-10T16:00:00.000Z</published>
    <updated>2020-11-01T13:59:30.931Z</updated>
    
    <content type="html"><![CDATA[<p>拥有指定的权限才可以进行相应的操作。</p><a id="more"></a><p>有一些操作是所有人都可以执行的，比如：访问首页、访问登录界面。而有一些就需要管理员权限，比如：删除用户。</p><p>为了实现这种功能，Shiro 提供了<strong>角色</strong>和<strong>权限</strong>两个概念。</p><p>推荐一篇博客：<a href="https://mrbird.cc/Spring-Boot-Shiro%20Authorization.html" target="_blank" rel="noopener">Spring Boot Shiro权限控制</a></p><p>我的理解是：一个用户对应一个或多个角色，一个角色又对应一个或多个权限。这样一来，用户就对应了多个明确的角色或者权限。然后设置接口所需要的角色或权限，实现权限控制。</p><p>在 Web 应用中，角色、权限都存放在数据库中，当然了还有用户表，以及<em>用户-角色表</em>、<em>角色-权限表</em>，总共有五个数据表。</p><p>当 Shiro 需要验证权限的时候，就需要从数据库中查找数据。</p><p>那么需要查找的是什么呢？</p><p>先看看 Shiro 需要的是什么。Realm 除了认证功能之外，还有授权的功能，对应的就是 doGetAuthorizationInfo 方法。在这个方法中返回的是一个 AuthorizationInfo 对象，而这个对象有两个方法：setRoles 和 setStringPermissions。</p><p>也就是说，Shiro 需要用户所对应的多个角色，以及多个权限。那么在数据访问层要做的就是查找一个用户所对应的角色和权限。</p><p>大概了解授权的流程之后，下面就具体说该怎么做。</p><h1 id="创建数据表"><a href="#创建数据表" class="headerlink" title="创建数据表"></a>创建数据表</h1><p>建议阅读上面推荐的文章，讲得比较详细。</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br></pre></td><td class="code"><pre><span class="line">CREATE DATABASE <span class="comment">/*!32312 IF NOT EXISTS*/</span>`shiro-login` <span class="comment">/*!40100 DEFAULT CHARACTER SET utf8 */</span>;</span><br><span class="line"></span><br><span class="line">USE `shiro-login`;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Table structure for table `t_permission` */</span></span><br><span class="line"></span><br><span class="line">DROP TABLE IF EXISTS `t_permission`;</span><br><span class="line"></span><br><span class="line">CREATE TABLE `t_permission` (</span><br><span class="line">  `id` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL AUTO_INCREMENT,</span><br><span class="line">  `url` varchar(<span class="number">50</span>) NOT NULL,</span><br><span class="line">  `name` varchar(<span class="number">100</span>) NOT NULL,</span><br><span class="line">  <span class="function">PRIMARY <span class="title">KEY</span> <span class="params">(`id`)</span></span></span><br><span class="line"><span class="function">) ENGINE</span>=InnoDB AUTO_INCREMENT=<span class="number">4</span> DEFAULT CHARSET=utf8;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Table structure for table `t_role` */</span></span><br><span class="line"></span><br><span class="line">DROP TABLE IF EXISTS `t_role`;</span><br><span class="line"></span><br><span class="line">CREATE TABLE `t_role` (</span><br><span class="line">  `id` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL AUTO_INCREMENT,</span><br><span class="line">  `name` varchar(<span class="number">20</span>) NOT NULL,</span><br><span class="line">  `memo` varchar(<span class="number">50</span>) NOT NULL,</span><br><span class="line">  <span class="function">PRIMARY <span class="title">KEY</span> <span class="params">(`id`)</span></span></span><br><span class="line"><span class="function">) ENGINE</span>=InnoDB AUTO_INCREMENT=<span class="number">3</span> DEFAULT CHARSET=utf8;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Table structure for table `t_role_permission` */</span></span><br><span class="line"></span><br><span class="line">DROP TABLE IF EXISTS `t_role_permission`;</span><br><span class="line"></span><br><span class="line">CREATE TABLE `t_role_permission` (</span><br><span class="line">  `rid` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL,</span><br><span class="line">  `pid` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL,</span><br><span class="line">  <span class="function">PRIMARY <span class="title">KEY</span> <span class="params">(`rid`,`pid`)</span></span></span><br><span class="line"><span class="function">) ENGINE</span>=InnoDB DEFAULT CHARSET=utf8;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Table structure for table `t_user` */</span></span><br><span class="line"></span><br><span class="line">DROP TABLE IF EXISTS `t_user`;</span><br><span class="line"></span><br><span class="line">CREATE TABLE `t_user` (</span><br><span class="line">  `id` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL AUTO_INCREMENT,</span><br><span class="line">  `username` varchar(<span class="number">20</span>) NOT NULL,</span><br><span class="line">  `password` varchar(<span class="number">100</span>) NOT NULL,</span><br><span class="line">  `salt` varchar(<span class="number">20</span>) NOT NULL,</span><br><span class="line">  <span class="function">PRIMARY <span class="title">KEY</span> <span class="params">(`id`)</span>,</span></span><br><span class="line"><span class="function">  UNIQUE KEY `username` <span class="params">(`username`)</span></span></span><br><span class="line"><span class="function">) ENGINE</span>=InnoDB AUTO_INCREMENT=<span class="number">10</span> DEFAULT CHARSET=utf8;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Table structure for table `t_user_role` */</span></span><br><span class="line"></span><br><span class="line">DROP TABLE IF EXISTS `t_user_role`;</span><br><span class="line"></span><br><span class="line">CREATE TABLE `t_user_role` (</span><br><span class="line">  `uid` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL,</span><br><span class="line">  `rid` <span class="keyword">int</span>(<span class="number">11</span>) NOT NULL,</span><br><span class="line">  <span class="function">PRIMARY <span class="title">KEY</span> <span class="params">(`uid`,`rid`)</span></span></span><br><span class="line"><span class="function">) ENGINE</span>=InnoDB DEFAULT CHARSET=utf8;</span><br></pre></td></tr></table></figure><h1 id="插入数据"><a href="#插入数据" class="headerlink" title="插入数据"></a>插入数据</h1><p>数据仅供参考，根据自己的设计插入数据。</p><figure class="highlight sql"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">CREATE</span> <span class="keyword">DATABASE</span> <span class="comment">/*!32312 IF NOT EXISTS*/</span><span class="string">`shiro-login`</span> <span class="comment">/*!40100 DEFAULT CHARACTER SET utf8 */</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">USE</span> <span class="string">`shiro-login`</span>;</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Data for the table `t_permission` */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">insert</span>  <span class="keyword">into</span> <span class="string">`t_permission`</span>(<span class="string">`id`</span>,<span class="string">`url`</span>,<span class="string">`name`</span>) <span class="keyword">values</span> </span><br><span class="line">(<span class="number">1</span>,<span class="string">'/user'</span>,<span class="string">'user:add'</span>),</span><br><span class="line">(<span class="number">2</span>,<span class="string">'/user'</span>,<span class="string">'user:delete'</span>),</span><br><span class="line">(<span class="number">3</span>,<span class="string">'/user'</span>,<span class="string">'user:see'</span>);</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Data for the table `t_role` */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">insert</span>  <span class="keyword">into</span> <span class="string">`t_role`</span>(<span class="string">`id`</span>,<span class="string">`name`</span>,<span class="string">`memo`</span>) <span class="keyword">values</span> </span><br><span class="line">(<span class="number">1</span>,<span class="string">'admin'</span>,<span class="string">'超级管理员'</span>),</span><br><span class="line">(<span class="number">2</span>,<span class="string">'test'</span>,<span class="string">'测试用户'</span>);</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Data for the table `t_role_permission` */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">insert</span>  <span class="keyword">into</span> <span class="string">`t_role_permission`</span>(<span class="string">`rid`</span>,<span class="string">`pid`</span>) <span class="keyword">values</span> </span><br><span class="line">(<span class="number">1</span>,<span class="number">1</span>),</span><br><span class="line">(<span class="number">1</span>,<span class="number">2</span>),</span><br><span class="line">(<span class="number">1</span>,<span class="number">3</span>),</span><br><span class="line">(<span class="number">2</span>,<span class="number">3</span>);</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Data for the table `t_user` */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">insert</span>  <span class="keyword">into</span> <span class="string">`t_user`</span>(<span class="string">`id`</span>,<span class="string">`username`</span>,<span class="string">`password`</span>,<span class="string">`salt`</span>) <span class="keyword">values</span> </span><br><span class="line">(<span class="number">1</span>,<span class="string">'zs'</span>,<span class="string">'6f294b522deba0531722c92b4199c6b95d76b00e231ca2c765aae8c32fd36222'</span>,<span class="string">'zsreg'</span>),</span><br><span class="line">(<span class="number">2</span>,<span class="string">'root'</span>,<span class="string">'6a9629cd8b8c68a86c800cdeae59f2b3185bb6ce1c0896a675e91a860c7702ee'</span>,<span class="string">'rootreg'</span>),</span><br><span class="line">(<span class="number">3</span>,<span class="string">'admin'</span>,<span class="string">'dddf9fe0979a7db4fbf06a2366c5862e775fd702c56249decb372e876636b9ab'</span>,<span class="string">'adminreg'</span>),</span><br><span class="line">(<span class="number">8</span>,<span class="string">'aaa'</span>,<span class="string">'02d66435c563cc9130876fc5d7c1496e6b451345741b46d1472de3d6c82a8afa'</span>,<span class="string">'aaareg'</span>),</span><br><span class="line">(<span class="number">9</span>,<span class="string">'aaaa'</span>,<span class="string">'b344150010d7630f0422fdd9f491a450a8299831e28c78b2f5173ed5b1fd164e'</span>,<span class="string">'aaaareg'</span>);</span><br><span class="line"></span><br><span class="line"><span class="comment">/*Data for the table `t_user_role` */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">insert</span>  <span class="keyword">into</span> <span class="string">`t_user_role`</span>(<span class="string">`uid`</span>,<span class="string">`rid`</span>) <span class="keyword">values</span> </span><br><span class="line">(<span class="number">2</span>,<span class="number">1</span>),</span><br><span class="line">(<span class="number">9</span>,<span class="number">2</span>);</span><br></pre></td></tr></table></figure><h1 id="创建实体类"><a href="#创建实体类" class="headerlink" title="创建实体类"></a>创建实体类</h1><p>使用 IDEA 自动生成即可。</p><h1 id="UserRoleMapper"><a href="#UserRoleMapper" class="headerlink" title="UserRoleMapper"></a>UserRoleMapper</h1><p>根据用户名查找角色集：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Mapper</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">interface</span> <span class="title">UserRoleMapper</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">    <span class="meta">@Select</span>(<span class="string">"SELECT t_role.name FROM t_role, t_user, t_user_role WHERE t_user.`id` = t_user_role.`uid` AND t_user.`username` = #&#123;username&#125; AND t_user_role.`rid` = t_role.`id`"</span>)</span><br><span class="line">    <span class="function">List&lt;TRole&gt; <span class="title">findRolesByUsername</span><span class="params">(String username)</span></span>;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="UserPermissionMapper"><a href="#UserPermissionMapper" class="headerlink" title="UserPermissionMapper"></a>UserPermissionMapper</h1><p>根据用户名查找权限集：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Mapper</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">interface</span> <span class="title">UserPermissionMapper</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">    <span class="meta">@Select</span>(<span class="string">"SELECT p.* FROM t_user u LEFT JOIN t_user_role ur ON u.`id` = ur.`uid` LEFT JOIN t_role r ON ur.`rid` = r.`id` LEFT JOIN t_role_permission rp ON r.`id` = rp.`rid` LEFT JOIN t_permission p ON rp.`pid` = p.`id` WHERE u.`username` = #&#123;username&#125; "</span>)</span><br><span class="line">    <span class="function">List&lt;TPermission&gt; <span class="title">findPermissonsByUsername</span><span class="params">(String username)</span></span>;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="Realm-添加方法"><a href="#Realm-添加方法" class="headerlink" title="Realm 添加方法"></a>Realm 添加方法</h1><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Autowired</span></span><br><span class="line"><span class="keyword">private</span> UserRoleMapper userRoleMapper;</span><br><span class="line"></span><br><span class="line"><span class="meta">@Autowired</span></span><br><span class="line"><span class="keyword">private</span> UserPermissionMapper userPermissionMapper;</span><br><span class="line"></span><br><span class="line"><span class="meta">@Override</span></span><br><span class="line"><span class="function"><span class="keyword">protected</span> AuthorizationInfo <span class="title">doGetAuthorizationInfo</span><span class="params">(PrincipalCollection principals)</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">    String username = (String) SecurityUtils.getSubject().getPrincipal();</span><br><span class="line"></span><br><span class="line">    List&lt;TRole&gt; roles = userRoleMapper.findRolesByUsername(username);</span><br><span class="line"></span><br><span class="line">    SimpleAuthorizationInfo info = <span class="keyword">new</span> SimpleAuthorizationInfo();</span><br><span class="line">    Set&lt;String&gt; roleSet = <span class="keyword">new</span> HashSet&lt;&gt;();</span><br><span class="line">    <span class="keyword">for</span> (TRole t : roles) &#123;</span><br><span class="line">        roleSet.add(t.getName());</span><br><span class="line">        System.out.println(t.getName());</span><br><span class="line">    &#125;</span><br><span class="line">    info.setRoles(roleSet);</span><br><span class="line"></span><br><span class="line">    List&lt;TPermission&gt; ps = userPermissionMapper.findPermissonsByUsername(username);</span><br><span class="line"></span><br><span class="line">    Set&lt;String&gt; pSet = <span class="keyword">new</span> HashSet&lt;&gt;();</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (TPermission p : ps) &#123;</span><br><span class="line"></span><br><span class="line">        <span class="comment">//            如果在 mapper 没有查到任何数据，ps 也不为 null，但是 ps.get(0) 的值是 null</span></span><br><span class="line">        <span class="keyword">if</span> (p != <span class="keyword">null</span>) &#123;</span><br><span class="line">            pSet.add(p.getName());</span><br><span class="line">            System.out.println(p.getName());</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    info.setStringPermissions(pSet);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> info;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="添加权限控制"><a href="#添加权限控制" class="headerlink" title="添加权限控制"></a>添加权限控制</h1><h2 id="方法一：配置文件中"><a href="#方法一：配置文件中" class="headerlink" title="方法一：配置文件中"></a>方法一：配置文件中</h2><p>在 ShiroConfig 类的 shiroFilterChainDefinition 方法中：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@Bean</span></span><br><span class="line"><span class="function"><span class="keyword">public</span> ShiroFilterChainDefinition <span class="title">shiroFilterChainDefinition</span><span class="params">()</span> </span>&#123;</span><br><span class="line">    DefaultShiroFilterChainDefinition chainDefinition = <span class="keyword">new</span> DefaultShiroFilterChainDefinition();</span><br><span class="line"></span><br><span class="line">    <span class="comment">//        authc 是必须通过认证，而不是“记住我”</span></span><br><span class="line">    chainDefinition.addPathDefinition(<span class="string">"/admin/**"</span>, <span class="string">"roles[admin]"</span>);</span><br><span class="line"></span><br><span class="line">    chainDefinition.addPathDefinition(<span class="string">"/me/**"</span>, <span class="string">"roles[admin]"</span>);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> chainDefinition;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h2 id="方法二：使用注解"><a href="#方法二：使用注解" class="headerlink" title="方法二：使用注解"></a>方法二：使用注解</h2><p>在 Controller 的接口上配置：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 表示当前Subject已经通过login进行了身份验证；即Subject.isAuthenticated()返回true。</span></span><br><span class="line"><span class="meta">@RequiresAuthentication</span>  </span><br><span class="line"> </span><br><span class="line"><span class="comment">// 表示当前Subject已经身份验证或者通过记住我登录的。</span></span><br><span class="line"><span class="meta">@RequiresUser</span>  </span><br><span class="line"></span><br><span class="line"><span class="comment">// 表示当前Subject没有身份验证或通过记住我登录过，即是游客身份。</span></span><br><span class="line"><span class="meta">@RequiresGuest</span>  </span><br><span class="line"></span><br><span class="line"><span class="comment">// 表示当前Subject需要角色admin和user。  </span></span><br><span class="line"><span class="meta">@RequiresRoles</span>(value=&#123;<span class="string">"admin"</span>, <span class="string">"user"</span>&#125;, logical= Logical.AND)  </span><br><span class="line"></span><br><span class="line"><span class="comment">// 表示当前Subject需要权限user:a或user:b。</span></span><br><span class="line"><span class="meta">@RequiresPermissions</span> (value=&#123;<span class="string">"user:a"</span>, <span class="string">"user:b"</span>&#125;, logical= Logical.OR)</span><br></pre></td></tr></table></figure><h1 id="定义授权失败跳转页面"><a href="#定义授权失败跳转页面" class="headerlink" title="定义授权失败跳转页面"></a>定义授权失败跳转页面</h1><p>在 properties 文件中：</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">shiro.unauthorizedUrl=/error123</span><br><span class="line">shiro.loginUrl=/toLogin</span><br></pre></td></tr></table></figure><h1 id="捕获全局异常"><a href="#捕获全局异常" class="headerlink" title="捕获全局异常"></a>捕获全局异常</h1><h2 id="两种情况"><a href="#两种情况" class="headerlink" title="两种情况"></a>两种情况</h2><ul><li>一个接口使用注解指定了所需要的权限，当<strong>没有登录</strong>或者<strong>没有权限</strong>访问这个接口时，它不会跳转到失败页面，也不会跳转到登录页面，而是抛出一个异常。</li><li>在配置文件中指定一个接口所需的权限，那么它就会跳转到错误页面或者登录界面。</li></ul><p>为了解决第一种情况，就需要捕获异常：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@RestControllerAdvice</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">ShiroExceptionHandler</span> </span>&#123; </span><br><span class="line">    <span class="meta">@ExceptionHandler</span>(value = AuthorizationException.class)</span><br><span class="line">    <span class="function"><span class="keyword">public</span> String <span class="title">handleAuthorizationException</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="string">"没有权限访问"</span>;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure><h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><ul><li>创建角色和权限</li><li>查询角色和权限</li><li>重写 doGetAuthorizationInfo</li><li>给接口配置权限</li></ul>]]></content>
    
    <summary type="html">
    
      &lt;p&gt;拥有指定的权限才可以进行相应的操作。&lt;/p&gt;
    
    </summary>
    
      <category term="Spring Boot" scheme="/categories/Spring-Boot/"/>
    
    
  </entry>
  
</feed>