The use of view technologies in Spring MVC is pluggable, whether you decide to use Thymeleaf, Groovy Markup Templates, JSPs, or other technologies, is primarily a matter of a configuration change. This chapter covers view technologies integrated with Spring MVC. We assume you are already familiar with [mvc-viewresolver].
Thymeleaf is a modern server-side Java template engine that emphasizes natural HTML templates that can be previewed in a browser by double-clicking, which is very helpful for independent work on UI templates (for example, by a designer) without the need for a running server. If you want to replace JSPs, Thymeleaf offers one of the most extensive set of features to make such a transition easier. Thymeleaf is actively developed and maintained. For a more complete introduction, see the Thymeleaf project home page.
The Thymeleaf integration with Spring MVC is managed by the Thymeleaf project.
The configuration involves a few bean declarations, such as
ServletContextTemplateResolver
, SpringTemplateEngine
, and ThymeleafViewResolver
.
See Thymeleaf+Spring for more details.
Apache FreeMarker is a template engine for generating any kind of text output from HTML to email and others. The Spring Framework has a built-in integration for using Spring MVC with FreeMarker templates.
The following example shows how to configure FreeMarker as a view technology:
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Override
public void configureViewResolvers(ViewResolverRegistry registry) {
registry.freemarker();
}
// Configure FreeMarker...
@Bean
public FreeMarkerConfigurer freeMarkerConfigurer() {
FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
configurer.setTemplateLoaderPath("/WEB-INF/freemarker");
return configurer;
}
}
The following example shows how to configure the same in XML:
<mvc:annotation-driven/>
<mvc:view-resolvers>
<mvc:freemarker/>
</mvc:view-resolvers>
<!-- Configure FreeMarker... -->
<mvc:freemarker-configurer>
<mvc:template-loader-path location="/WEB-INF/freemarker"/>
</mvc:freemarker-configurer>
Alternatively, you can also declare the FreeMarkerConfigurer
bean for full control over all
properties, as the following example shows:
<bean id="freemarkerConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
<property name="templateLoaderPath" value="/WEB-INF/freemarker/"/>
</bean>
Your templates need to be stored in the directory specified by the FreeMarkerConfigurer
shown in the preceding example. Given the preceding configuration, if your controller returns a view name
of welcome
, the resolver looks for the /WEB-INF/freemarker/welcome.ftl
template.
You can pass FreeMarker 'Settings' and 'SharedVariables' directly to the FreeMarker
Configuration
object (which is managed by Spring) by setting the appropriate bean properties on
the FreeMarkerConfigurer
bean. The freemarkerSettings
property requires a
java.util.Properties
object, and the freemarkerVariables
property requires a
java.util.Map
. The following example shows how to do so:
<bean id="freemarkerConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
<property name="templateLoaderPath" value="/WEB-INF/freemarker/"/>
<property name="freemarkerVariables">
<map>
<entry key="xml_escape" value-ref="fmXmlEscape"/>
</map>
</property>
</bean>
<bean id="fmXmlEscape" class="freemarker.template.utility.XmlEscape"/>
See the FreeMarker documentation for details of settings and variables as they apply to
the Configuration
object.
Spring provides a tag library for use in JSPs that contains, among others, a
<spring:bind/>
element. This element primarily lets forms display values from
form-backing objects and show the results of failed validations from a Validator
in the
web or business tier. Spring also has support for the same functionality in FreeMarker,
with additional convenience macros for generating form input elements themselves.
A standard set of macros are maintained within the spring-webmvc.jar
file for both
languages, so they are always available to a suitably configured application.
Some of the macros defined in the Spring libraries are considered internal (private), but
no such scoping exists in the macro definitions, making all macros visible to calling
code and user templates. The following sections concentrate only on the macros you need
to directly call from within your templates. If you wish to view the macro code
directly, the file is called spring.ftl
and is in the
org.springframework.web.servlet.view.freemarker
package.
In your HTML forms (vm or ftl templates) that act as a form view for a Spring MVC
controller, you can use code similar to the next example to bind to field values and
display error messages for each input field in similar fashion to the JSP equivalent.
The following example shows the personForm
view that was configured earlier:
<!-- freemarker macros have to be imported into a namespace. We strongly
recommend sticking to 'spring' -->
<#import "/spring.ftl" as spring/>
<html>
...
<form action="" method="POST">
Name:
<@spring.bind "myModelObject.name"/>
<input type="text"
name="${spring.status.expression}"
value="${spring.status.value?html}"/><br>
<#list spring.status.errorMessages as error> <b>${error}</b> <br> </#list>
<br>
...
<input type="submit" value="submit"/>
</form>
...
</html>
<@spring.bind>
requires a 'path' argument, which consists of the name of your command
object (it is 'command', unless you changed it in your FormController
properties)
followed by a period and the name of the field on the command object to which you wish to bind.
You can also use nested fields, such as command.address.street
. The bind
macro assumes
the default HTML escaping behavior specified by the ServletContext parameter
defaultHtmlEscape
in web.xml
.
The optional form of the macro called <@spring.bindEscaped>
takes a second argument
and explicitly specifies whether HTML escaping should be used in the status error
messages or values. You can set it to true
or false
as required. Additional form handling macros
simplify the use of HTML escaping, and you should use these macros wherever possible.
They are explained in the next section.
Additional convenience macros for both languages simplify both binding and form generation (including validation error display). It is never necessary to use these macros to generate form input fields, and you can mix and match them with simple HTML or direct calls to the spring bind macros that we highlighted previously.
The following table of available macros shows the FTL definitions and the parameter list that each takes:
macro | FTL definition |
---|---|
|
<@spring.message code/> |
|
<@spring.messageText code, text/> |
|
<@spring.url relativeUrl/> |
|
<@spring.formInput path, attributes, fieldType/> |
|
<@spring.formHiddenInput path, attributes/> |
|
<@spring.formPasswordInput path, attributes/> |
|
<@spring.formTextarea path, attributes/> |
|
<@spring.formSingleSelect path, options, attributes/> |
|
<@spring.formMultiSelect path, options, attributes/> |
|
<@spring.formRadioButtons path, options separator, attributes/> |
|
<@spring.formCheckboxes path, options, separator, attributes/> |
|
<@spring.formCheckbox path, attributes/> |
|
<@spring.showErrors separator, classOrStyle/> |
-
In FTL (FreeMarker),
formHiddenInput
andformPasswordInput
are not actually required, as you can use the normalformInput
macro, specifyinghidden
orpassword
as the value for thefieldType
parameter.
The parameters to any of the above macros have consistent meanings:
-
path
: The name of the field to bind to (ie "command.name") -
options
: AMap
of all the available values that can be selected from in the input field. The keys to the map represent the values that are POSTed back from the form and bound to the command object. Map objects stored against the keys are the labels displayed on the form to the user and may be different from the corresponding values posted back by the form. Usually, such a map is supplied as reference data by the controller. You can use anyMap
implementation, depending on required behavior. For strictly sorted maps, you can use aSortedMap
(such as aTreeMap
) with a suitableComparator
and, for arbitrary Maps that should return values in insertion order, use aLinkedHashMap
or aLinkedMap
fromcommons-collections
. -
separator
: Where multiple options are available as discreet elements (radio buttons or checkboxes), the sequence of characters used to separate each one in the list (such as<br>
). -
attributes
: An additional string of arbitrary tags or text to be included within the HTML tag itself. This string is echoed literally by the macro. For example, in atextarea
field, you may supply attributes (such as 'rows="5" cols="60"'), or you could pass style information such as 'style="border:1px solid silver"'. -
classOrStyle
: For theshowErrors
macro, the name of the CSS class that thespan
element that wraps each error uses. If no information is supplied (or the value is empty), the errors are wrapped in<b></b>
tags.
The following sections outline examples of the macros (some in FTL and some in VTL). Where usage differences exist between the two languages, they are explained in the notes.
The formInput
macro takes the path
parameter (command.name
) and an additional attributes
parameter (which is empty in the upcoming example). The macro, along with all other form
generation macros, performs an implicit Spring bind on the path parameter. The binding
remains valid until a new bind occurs, so the showErrors
macro does not need to pass the
path parameter again — it operates on the field for which a bind was last created.
The showErrors
macro takes a separator parameter (the characters that are used to
separate multiple errors on a given field) and also accepts a second parameter — this
time, a class name or style attribute. Note that FreeMarker can specify default
values for the attributes parameter. The following example shows how to use the formInput
and showWErrors
macros:
<@spring.formInput "command.name"/>
<@spring.showErrors "<br>"/>
The next example shows the output of the form fragment, generating the name field and displaying a validation error after the form was submitted with no value in the field. Validation occurs through Spring’s Validation framework.
The generated HTML resembles the following example:
Name:
<input type="text" name="name" value="">
<br>
<b>required</b>
<br>
<br>
The formTextarea
macro works the same way as the formInput
macro and accepts the same
parameter list. Commonly, the second parameter (attributes) is used to pass style
information or rows
and cols
attributes for the textarea
.
You can use four selection field macros to generate common UI value selection inputs in your HTML forms:
-
formSingleSelect
-
formMultiSelect
-
formRadioButtons
-
formCheckboxes
Each of the four macros accepts a Map
of options that contains the value for the form
field and the label that corresponds to that value. The value and the label can be the
same.
The next example is for radio buttons in FTL. The form-backing object specifies a default value of 'London' for this field, so no validation is necessary. When the form is rendered, the entire list of cities to choose from is supplied as reference data in the model under the name 'cityMap'. The following listing shows the example:
...
Town:
<@spring.formRadioButtons "command.address.town", cityMap, ""/><br><br>
The preceding listing renders a line of radio buttons, one for each value in cityMap
, and uses a
separator of ""
. No additional attributes are supplied (the last parameter to the macro is
missing). The cityMap
uses the same String
for each key-value pair in the map. The map’s
keys are what the form actually submits as POSTed request parameters. The map values are the
labels that the user sees. In the preceding example, given a list of three well known cities
and a default value in the form backing object, the HTML resembles the following:
Town:
<input type="radio" name="address.town" value="London">London</input>
<input type="radio" name="address.town" value="Paris" checked="checked">Paris</input>
<input type="radio" name="address.town" value="New York">New York</input>
If your application expects to handle cities by internal codes (for example), you can create the map of codes with suitable keys, as the following example shows:
protected Map<String, String> referenceData(HttpServletRequest request) throws Exception {
Map<String, String> cityMap = new LinkedHashMap<>();
cityMap.put("LDN", "London");
cityMap.put("PRS", "Paris");
cityMap.put("NYC", "New York");
Map<String, String> model = new HashMap<>();
model.put("cityMap", cityMap);
return model;
}
The code now produces output where the radio values are the relevant codes, but the user still sees the more user-friendly city names, as follows:
Town:
<input type="radio" name="address.town" value="LDN">London</input>
<input type="radio" name="address.town" value="PRS" checked="checked">Paris</input>
<input type="radio" name="address.town" value="NYC">New York</input>
Default usage of the form macros described earlier results in HTML elemets that are HTML 4.01
compliant and that use the default value for HTML escaping defined in your web.xml
file, as
used by Spring’s bind support. To make the elements be XHTML compliant or to override
the default HTML escaping value, you can specify two variables in your template (or in
your model, where they are visible to your templates). The advantage of specifying
them in the templates is that they can be changed to different values later in the
template processing to provide different behavior for different fields in your form.
To switch to XHTML compliance for your tags, specify a value of true
for a
model or context variable named xhtmlCompliant
, as the following example shows:
<#-- for FreeMarker -->
<#assign xhtmlCompliant = true>
After processing this directive, any elements generated by the Spring macros are now XHTML compliant.
In similar fashion, you can specify HTML escaping per field, as the following example shows:
<#-- until this point, default HTML escaping is used -->
<#assign htmlEscape = true>
<#-- next field will use HTML escaping -->
<@spring.formInput "command.name"/>
<#assign htmlEscape = false in spring>
<#-- all future fields will be bound with HTML escaping off -->
The Groovy Markup Template Engine is primarily aimed at generating XML-like markup (XML, XHTML, HTML5, and others), but you can use it to generate any text-based content. The Spring Framework has a built-in integration for using Spring MVC with Groovy Markup.
Note
|
The Groovy Markup Template engine requires Groovy 2.3.1+. |
The following example shows how to configure the Groovy Markup Template Engine:
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Override
public void configureViewResolvers(ViewResolverRegistry registry) {
registry.groovy();
}
// Configure the Groovy Markup Template Engine...
@Bean
public GroovyMarkupConfigurer groovyMarkupConfigurer() {
GroovyMarkupConfigurer configurer = new GroovyMarkupConfigurer();
configurer.setResourceLoaderPath("/WEB-INF/");
return configurer;
}
}
The following example shows how to configure the same in XML:
<mvc:annotation-driven/>
<mvc:view-resolvers>
<mvc:groovy/>
</mvc:view-resolvers>
<!-- Configure the Groovy Markup Template Engine... -->
<mvc:groovy-configurer resource-loader-path="/WEB-INF/"/>
Unlike traditional template engines, Groovy Markup relies on a DSL that uses a builder syntax. The following example shows a sample template for an HTML page:
yieldUnescaped '<!DOCTYPE html>'
html(lang:'en') {
head {
meta('http-equiv':'"Content-Type" content="text/html; charset=utf-8"')
title('My page')
}
body {
p('This is an example of HTML contents')
}
}
The Spring Framework has a built-in integration for using Spring MVC with any templating library that can run on top of the JSR-223 Java scripting engine. We have tested the following templating libraries on different script engines:
Scripting Library | Scripting Engine |
---|---|
Tip
|
The basic rule for integrating any other script engine is that it must implement the
ScriptEngine and Invocable interfaces.
|
You need to have the script engine on your classpath, the details of which vary by script engine:
-
The Nashorn JavaScript engine is provided with Java 8+. Using the latest update release available is highly recommended.
-
JRuby should be added as a dependency for Ruby support.
-
Jython should be added as a dependency for Python support.
-
org.jetbrains.kotlin:kotlin-script-util
dependency and aMETA-INF/services/javax.script.ScriptEngineFactory
file containing aorg.jetbrains.kotlin.script.jsr223.KotlinJsr223JvmLocalScriptEngineFactory
line should be added for Kotlin script support. See this example for more details.
You need to have the script templating library. One way to do that for Javascript is through WebJars.
You can declare a ScriptTemplateConfigurer
bean to specify the script engine to use,
the script files to load, what function to call to render templates, and so on.
The following example uses Mustache templates and the Nashorn JavaScript engine:
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Override
public void configureViewResolvers(ViewResolverRegistry registry) {
registry.scriptTemplate();
}
@Bean
public ScriptTemplateConfigurer configurer() {
ScriptTemplateConfigurer configurer = new ScriptTemplateConfigurer();
configurer.setEngineName("nashorn");
configurer.setScripts("mustache.js");
configurer.setRenderObject("Mustache");
configurer.setRenderFunction("render");
return configurer;
}
}
The following example shows the same arrangement in XML:
<mvc:annotation-driven/>
<mvc:view-resolvers>
<mvc:script-template/>
</mvc:view-resolvers>
<mvc:script-template-configurer engine-name="nashorn" render-object="Mustache" render-function="render">
<mvc:script location="mustache.js"/>
</mvc:script-template-configurer>
The controller would look no different for the Java and XML configurations, as the following example shows:
@Controller
public class SampleController {
@GetMapping("/sample")
public String test(Model model) {
model.addObject("title", "Sample title");
model.addObject("body", "Sample body");
return "template";
}
}
The following example shows the Mustache template:
<html>
<head>
<title>{{title}}</title>
</head>
<body>
<p>{{body}}</p>
</body>
</html>
The render function is called with the following parameters:
-
String template
: The template content -
Map model
: The view model -
RenderingContext renderingContext
: The {api-spring-framework}/web/servlet/view/script/RenderingContext.html[RenderingContext
] that gives access to the application context, the locale, the template loader, and the URL (since 5.0)
Mustache.render()
is natively compatible with this signature, so you can call it directly.
If your templating technology requires some customization, you can provide a script that implements a custom render function. For example, Handlerbars needs to compile templates before using them and requires a polyfill to emulate some browser facilities that are not available in the server-side script engine.
The following example shows how to do so:
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Override
public void configureViewResolvers(ViewResolverRegistry registry) {
registry.scriptTemplate();
}
@Bean
public ScriptTemplateConfigurer configurer() {
ScriptTemplateConfigurer configurer = new ScriptTemplateConfigurer();
configurer.setEngineName("nashorn");
configurer.setScripts("polyfill.js", "handlebars.js", "render.js");
configurer.setRenderFunction("render");
configurer.setSharedEngine(false);
return configurer;
}
}
Note
|
Setting the sharedEngine property to false is required when you use non-thread-safe
script engines with templating libraries not designed for concurrency, such as Handlebars or
React running on Nashorn. In that case, Java 8u60 or greater is required, due
to this bug.
|
polyfill.js
defines only the window
object needed by Handlebars to run properly, as follows:
var window = {};
This basic render.js
implementation compiles the template before using it. A production-ready
implementation should also store any reused cached templates or pre-compiled templates.
You can do so on the script side (and handle any customization you need — managing
template engine configuration, for example). The following example shows how to do so:
function render(template, model) {
var compiledTemplate = Handlebars.compile(template);
return compiledTemplate(model);
}
The Spring Framework has a built-in integration for using Spring MVC with JSP and JSTL.
When developing with JSPs, you can declare a InternalResourceViewResolver
or a
ResourceBundleViewResolver
bean.
ResourceBundleViewResolver
relies on a properties file to define the view names
mapped to a class and a URL. With a ResourceBundleViewResolver
, you
can mix different types of views byusing only one resolver, as the following example shows:
<!-- the ResourceBundleViewResolver -->
<bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">
<property name="basename" value="views"/>
</bean>
# And a sample properties file is uses (views.properties in WEB-INF/classes):
welcome.(class)=org.springframework.web.servlet.view.JstlView
welcome.url=/WEB-INF/jsp/welcome.jsp
productList.(class)=org.springframework.web.servlet.view.JstlView
productList.url=/WEB-INF/jsp/productlist.jsp
InternalResourceBundleViewResolver
can also be used for JSPs. As a best practice, we
strongly encourage placing your JSP files in a directory under the 'WEB-INF'
directory so there can be no direct access by clients.
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean>
When using the Java Standard Tag Library you must use a special view class, the
JstlView
, as JSTL needs some preparation before things such as the I18N features can
work.
Spring provides data binding of request parameters to command objects, as described in earlier chapters. To facilitate the development of JSP pages in combination with those data binding features, Spring provides a few tags that make things even easier. All Spring tags have HTML escaping features to enable or disable escaping of characters.
The spring.tld
tag library descriptor (TLD) is included in the spring-webmvc.jar
.
For a comprehensive reference on individual tags, browse the
{api-spring-framework}/web/servlet/tags/package-summary.html#package.description[API reference]
or see the tag library description.
As of version 2.0, Spring provides a comprehensive set of data binding-aware tags for handling form elements when using JSP and Spring Web MVC. Each tag provides support for the set of attributes of its corresponding HTML tag counterpart, making the tags familiar and intuitive to use. The tag-generated HTML is HTML 4.01/XHTML 1.0 compliant.
Unlike other form/input tag libraries, Spring’s form tag library is integrated with Spring Web MVC, giving the tags access to the command object and reference data your controller deals with. As we show in the following examples, the form tags make JSPs easier to develop, read, and maintain.
We go through the form tags and look at an example of how each tag is used. We have included generated HTML snippets where certain tags require further commentary.
The form tag library comes bundled in spring-webmvc.jar
. The library descriptor is
called spring-form.tld
.
To use the tags from this library, add the following directive to the top of your JSP page:
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
where form
is the tag name prefix you want to use for the tags from this library.
This tag renders an HTML 'form' element and exposes a binding path to inner tags for
binding. It puts the command object in the PageContext
so that the command object can
be accessed by inner tags. All the other tags in this library are nested tags of the
form
tag.
Assume that we have a domain object called User
. It is a JavaBean with properties
such as firstName
and lastName
. We can use it as the form-backing object of our
form controller, which returns form.jsp
. The following example shows what form.jsp
could
look like:
<form:form>
<table>
<tr>
<td>First Name:</td>
<td><form:input path="firstName"/></td>
</tr>
<tr>
<td>Last Name:</td>
<td><form:input path="lastName"/></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form:form>
The firstName
and lastName
values are retrieved from the command object placed in
the PageContext
by the page controller. Keep reading to see more complex examples of
how inner tags are used with the form
tag.
The following listing shows the generated HTML, which looks like a standard form:
<form method="POST">
<table>
<tr>
<td>First Name:</td>
<td><input name="firstName" type="text" value="Harry"/></td>
</tr>
<tr>
<td>Last Name:</td>
<td><input name="lastName" type="text" value="Potter"/></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form>
The preceding JSP assumes that the variable name of the form-backing object is
command
. If you have put the form-backing object into the model under another name
(definitely a best practice), you can bind the form to the named variable, as the
following example shows:
<form:form modelAttribute="user">
<table>
<tr>
<td>First Name:</td>
<td><form:input path="firstName"/></td>
</tr>
<tr>
<td>Last Name:</td>
<td><form:input path="lastName"/></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form:form>
This tag renders an HTML input
element with the bound value and type='text'
by default.
For an example of this tag, see The Form Tag. You can also use
HTML5-specific types, such as email
, tel
, date
, and others.
This tag renders an HTML input
tag with the type
set to checkbox
.
Assume that our User
has preferences such as newsletter subscription and a list of
hobbies. The following example shows the Preferences
class:
public class Preferences {
private boolean receiveNewsletter;
private String[] interests;
private String favouriteWord;
public boolean isReceiveNewsletter() {
return receiveNewsletter;
}
public void setReceiveNewsletter(boolean receiveNewsletter) {
this.receiveNewsletter = receiveNewsletter;
}
public String[] getInterests() {
return interests;
}
public void setInterests(String[] interests) {
this.interests = interests;
}
public String getFavouriteWord() {
return favouriteWord;
}
public void setFavouriteWord(String favouriteWord) {
this.favouriteWord = favouriteWord;
}
}
The corresponding form.jsp
could then resemble the following:
<form:form>
<table>
<tr>
<td>Subscribe to newsletter?:</td>
<%-- Approach 1: Property is of type java.lang.Boolean --%>
<td><form:checkbox path="preferences.receiveNewsletter"/></td>
</tr>
<tr>
<td>Interests:</td>
<%-- Approach 2: Property is of an array or of type java.util.Collection --%>
<td>
Quidditch: <form:checkbox path="preferences.interests" value="Quidditch"/>
Herbology: <form:checkbox path="preferences.interests" value="Herbology"/>
Defence Against the Dark Arts: <form:checkbox path="preferences.interests" value="Defence Against the Dark Arts"/>
</td>
</tr>
<tr>
<td>Favourite Word:</td>
<%-- Approach 3: Property is of type java.lang.Object --%>
<td>
Magic: <form:checkbox path="preferences.favouriteWord" value="Magic"/>
</td>
</tr>
</table>
</form:form>
There are three approaches to the checkbox
tag, which should meet all your checkbox needs.
-
Approach One: When the bound value is of type
java.lang.Boolean
, theinput(checkbox)
is marked aschecked
if the bound value istrue
. Thevalue
attribute corresponds to the resolved value of thesetValue(Object)
value property. -
Approach Two: When the bound value is of type
array
orjava.util.Collection
, theinput(checkbox)
is marked aschecked
if the configuredsetValue(Object)
value is present in the boundCollection
. -
Approach Three: For any other bound value type, the
input(checkbox)
is marked aschecked
if the configuredsetValue(Object)
is equal to the bound value.
Note that, regardless of the approach, the same HTML structure is generated. The following HTML snippet defines some checkboxes:
<tr>
<td>Interests:</td>
<td>
Quidditch: <input name="preferences.interests" type="checkbox" value="Quidditch"/>
<input type="hidden" value="1" name="_preferences.interests"/>
Herbology: <input name="preferences.interests" type="checkbox" value="Herbology"/>
<input type="hidden" value="1" name="_preferences.interests"/>
Defence Against the Dark Arts: <input name="preferences.interests" type="checkbox" value="Defence Against the Dark Arts"/>
<input type="hidden" value="1" name="_preferences.interests"/>
</td>
</tr>
You might not expect to see the additional hidden field after each checkbox.
When a checkbox in an HTML page is not checked, its value is not sent to the
server as part of the HTTP request parameters once the form is submitted, so we need a
workaround for this quirk in HTML for Spring form data binding to work. The
checkbox
tag follows the existing Spring convention of including a hidden parameter
prefixed by an underscore (_
) for each checkbox. By doing this, you are effectively
telling Spring that “the checkbox was visible in the form, and I want my object to
which the form data binds to reflect the state of the checkbox, no matter what.”
This tag renders multiple HTML input
tags with the type
set to checkbox
.
This section build on the example from the previous checkbox
tag section. Sometimes, you prefer
not to have to list all the possible hobbies in your JSP page. You would rather provide
a list at runtime of the available options and pass that in to the tag. That is the
purpose of the checkboxes
tag. You can pass in an Array
, a List
, or a Map
that contains
the available options in the items
property. Typically, the bound property is a
collection so that it can hold multiple values selected by the user. The following example
shows a JSP that uses this tag:
<form:form>
<table>
<tr>
<td>Interests:</td>
<td>
<%-- Property is of an array or of type java.util.Collection --%>
<form:checkboxes path="preferences.interests" items="${interestList}"/>
</td>
</tr>
</table>
</form:form>
This example assumes that the interestList
is a List
available as a model attribute
that contains strings of the values to be selected from. If you use a Map
,
the map entry key is used as the value, and the map entry’s value is used as
the label to be displayed. You can also use a custom object where you can provide the
property names for the value by using itemValue
and the label by using itemLabel
.
This tag renders an HTML input
element with the type
set to radio
.
A typical usage pattern involves multiple tag instances bound to the same property but with different values, as the following example shows:
<tr>
<td>Sex:</td>
<td>
Male: <form:radiobutton path="sex" value="M"/> <br/>
Female: <form:radiobutton path="sex" value="F"/>
</td>
</tr>
This tag renders multiple HTML input
elements with the type
set to radio
.
As with the checkboxes
tag, you might want to pass in the available options as
a runtime variable. For this usage, you can use the radiobuttons
tag. You pass in an
Array
, a List
, or a Map
that contains the available options in the items
property.
If you use a Map
, the map entry key is used as the value and the map
entry’s value are used as the label to be displayed. You can also use a custom
object where you can provide the property names for the value by using itemValue
and the
label by using itemLabel
, as the following example shows:
<tr>
<td>Sex:</td>
<td><form:radiobuttons path="sex" items="${sexOptions}"/></td>
</tr>
This tag renders an HTML input
tag with the type set to password
with the bound value.
<tr>
<td>Password:</td>
<td>
<form:password path="password"/>
</td>
</tr>
Note that, by default, the password value is not shown. If you do want the
password value to be shown, you can set the value of the showPassword
attribute to
true
, as the following example shows:
<tr>
<td>Password:</td>
<td>
<form:password path="password" value="^76525bvHGq" showPassword="true"/>
</td>
</tr>
This tag renders an HTML 'select' element. It supports data binding to the selected
option as well as the use of nested option
and options
tags.
Assume that a User
has a list of skills. The corresponding HTML could be as follows:
<tr>
<td>Skills:</td>
<td><form:select path="skills" items="${skills}"/></td>
</tr>
If the User’s
skill are in Herbology, the HTML source of the 'Skills' row could be
as follows:
<tr>
<td>Skills:</td>
<td>
<select name="skills" multiple="true">
<option value="Potions">Potions</option>
<option value="Herbology" selected="selected">Herbology</option>
<option value="Quidditch">Quidditch</option>
</select>
</td>
</tr>
This tag renders an HTML option
element. It sets selected
, based on the bound
value. The following HTML shows typical output for it:
<tr>
<td>House:</td>
<td>
<form:select path="house">
<form:option value="Gryffindor"/>
<form:option value="Hufflepuff"/>
<form:option value="Ravenclaw"/>
<form:option value="Slytherin"/>
</form:select>
</td>
</tr>
If the User’s
house was in Gryffindor, the HTML source of the 'House' row would be
as follows:
<tr>
<td>House:</td>
<td>
<select name="house">
<option value="Gryffindor" selected="selected">Gryffindor</option> (1)
<option value="Hufflepuff">Hufflepuff</option>
<option value="Ravenclaw">Ravenclaw</option>
<option value="Slytherin">Slytherin</option>
</select>
</td>
</tr>
-
Note the addition of a
selected
attribute.
This tag renders a list of HTML option
elements. It sets the selected
attribute,
based on the bound value. The following HTML shows typical output for it:
<tr>
<td>Country:</td>
<td>
<form:select path="country">
<form:option value="-" label="--Please Select"/>
<form:options items="${countryList}" itemValue="code" itemLabel="name"/>
</form:select>
</td>
</tr>
If the User
lived in the UK, the HTML source of the 'Country' row would be as follows:
<tr>
<td>Country:</td>
<td>
<select name="country">
<option value="-">--Please Select</option>
<option value="AT">Austria</option>
<option value="UK" selected="selected">United Kingdom</option> (1)
<option value="US">United States</option>
</select>
</td>
</tr>
-
Note the addition of a
selected
attribute.
As the preceding example shows, the combined usage of an option
tag with the options
tag
generates the same standard HTML but lets you explicitly specify a value in the
JSP that is for display only (where it belongs), such as the default string in the
example: "-- Please Select".
The items
attribute is typically populated with a collection or array of item objects.
itemValue
and itemLabel
refer to bean properties of those item objects, if
specified. Otherwise, the item objects themselves are turned into strings. Alternatively,
you can specify a Map
of items, in which case the map keys are interpreted as option
values and the map values correspond to option labels. If itemValue
or itemLabel
(or both)
happen to be specified as well, the item value property applies to the map key, and
the item label property applies to the map value.
This tag renders an HTML textarea
element. The following HTML shows typical output for it:
<tr>
<td>Notes:</td>
<td><form:textarea path="notes" rows="3" cols="20"/></td>
<td><form:errors path="notes"/></td>
</tr>
The hidden
Tag
This tag renders an HTML input
tag with the type
set to hidden
with the bound value. To submit
an unbound hidden value, use the HTML input
tag with the type
set to hidden
.
The following HTML shows typical output for it:
<form:hidden path="house"/>
If we choose to submit the house
value as a hidden one, the HTML would be as follows:
<input name="house" type="hidden" value="Gryffindor"/>
This tag renders field errors in an HTML span
element. It provides access to the errors
created in your controller or those that were created by any validators associated with
your controller.
Assume that we want to display all error messages for the firstName
and lastName
fields once we submit the form. We have a validator for instances of the User
class
called UserValidator
, as the following example shows:
public class UserValidator implements Validator {
public boolean supports(Class candidate) {
return User.class.isAssignableFrom(candidate);
}
public void validate(Object obj, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", "required", "Field is required.");
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "lastName", "required", "Field is required.");
}
}
The form.jsp
could be as follows:
<form:form>
<table>
<tr>
<td>First Name:</td>
<td><form:input path="firstName"/></td>
<%-- Show errors for firstName field --%>
<td><form:errors path="firstName"/></td>
</tr>
<tr>
<td>Last Name:</td>
<td><form:input path="lastName"/></td>
<%-- Show errors for lastName field --%>
<td><form:errors path="lastName"/></td>
</tr>
<tr>
<td colspan="3">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form:form>
If we submit a form with empty values in the firstName
and lastName
fields,
the HTML would be as follows:
<form method="POST">
<table>
<tr>
<td>First Name:</td>
<td><input name="firstName" type="text" value=""/></td>
<%-- Associated errors to firstName field displayed --%>
<td><span name="firstName.errors">Field is required.</span></td>
</tr>
<tr>
<td>Last Name:</td>
<td><input name="lastName" type="text" value=""/></td>
<%-- Associated errors to lastName field displayed --%>
<td><span name="lastName.errors">Field is required.</span></td>
</tr>
<tr>
<td colspan="3">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form>
What if we want to display the entire list of errors for a given page? The next example
shows that the errors
tag also supports some basic wildcarding functionality.
-
path="*"
: Displays all errors. -
path="lastName"
: Displays all errors associated with thelastName
field. -
If
path
is omitted, only object errors are displayed.
The following example displays a list of errors at the top of the page, followed by field-specific errors next to the fields:
<form:form>
<form:errors path="*" cssClass="errorBox"/>
<table>
<tr>
<td>First Name:</td>
<td><form:input path="firstName"/></td>
<td><form:errors path="firstName"/></td>
</tr>
<tr>
<td>Last Name:</td>
<td><form:input path="lastName"/></td>
<td><form:errors path="lastName"/></td>
</tr>
<tr>
<td colspan="3">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form:form>
The HTML would be as follows:
<form method="POST">
<span name="*.errors" class="errorBox">Field is required.<br/>Field is required.</span>
<table>
<tr>
<td>First Name:</td>
<td><input name="firstName" type="text" value=""/></td>
<td><span name="firstName.errors">Field is required.</span></td>
</tr>
<tr>
<td>Last Name:</td>
<td><input name="lastName" type="text" value=""/></td>
<td><span name="lastName.errors">Field is required.</span></td>
</tr>
<tr>
<td colspan="3">
<input type="submit" value="Save Changes"/>
</td>
</tr>
</table>
</form>
The spring-form.tld
tag library descriptor (TLD) is included in the spring-webmvc.jar
.
For a comprehensive reference on individual tags, browse the
{api-spring-framework}/web/servlet/tags/form/package-summary.html#package.description[API reference]
or see the tag library description.
A key principle of REST is the use of the “Uniform Interface”. This means that all
resources (URLs) can be manipulated by using the same four HTTP methods: GET, PUT, POST,
and DELETE. For each method, the HTTP specification defines the exact semantics. For
instance, a GET should always be a safe operation, meaning that is has no side effects,
and a PUT or DELETE should be idempotent, meaning that you can repeat these operations
over and over again, but the end result should be the same. While HTTP defines these
four methods, HTML only supports two: GET and POST. Fortunately, there are two possible
workarounds: you can either use JavaScript to do your PUT or DELETE, or you can do a POST
with the “real” method as an additional parameter (modeled as a hidden input field in an
HTML form). Spring’s HiddenHttpMethodFilter
uses this latter trick. This
filter is a plain Servlet filter and, therefore, it can be used in combination with any
web framework (not just Spring MVC). Add this filter to your web.xml, and a POST
with a hidden method
parameter is converted into the corresponding HTTP method
request.
To support HTTP method conversion, the Spring MVC form tag was updated to support setting the HTTP method. For example, the following snippet comes from the Pet Clinic sample:
<form:form method="delete">
<p class="submit"><input type="submit" value="Delete Pet"/></p>
</form:form>
The preceding example perform an HTTP POST, with the “real” DELETE method hidden behind a
request parameter. It is picked up by the HiddenHttpMethodFilter
, which is defined in
web.xml, as the following example shows:
<filter>
<filter-name>httpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>httpMethodFilter</filter-name>
<servlet-name>petclinic</servlet-name>
</filter-mapping>
The following example shows the corresponding @Controller
method:
@RequestMapping(method = RequestMethod.DELETE)
public String deletePet(@PathVariable int ownerId, @PathVariable int petId) {
this.clinic.deletePet(petId);
return "redirect:/owners/" + ownerId;
}
The Spring form tag library allows entering dynamic attributes, which means you can enter any HTML5 specific attributes.
The form input
tag supports entering a type attribute other than text
. This is
intended to allow rendering new HTML5 specific input types, such as email
, date
,
range
, and others. Note that entering type='text'
is not required, since text
is the default type.
You can integrate Tiles - just as any other view technology - in web applications that use Spring. This section describes, in a broad way, how to do so.
Note
|
This section focuses on Spring’s support for Tiles version 3 in the
org.springframework.web.servlet.view.tiles3 package.
|
To be able to use Tiles, you have to add a dependency on Tiles version 3.0.1 or higher and its transitive dependencies to your project.
To be able to use Tiles, you have to configure it by using files that contain definitions
(for basic information on definitions and other Tiles concepts, see
http://tiles.apache.org). In Spring, this is done by using the TilesConfigurer
.
The following example ApplicationContext
configuration shows how to do so:
<bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles3.TilesConfigurer">
<property name="definitions">
<list>
<value>/WEB-INF/defs/general.xml</value>
<value>/WEB-INF/defs/widgets.xml</value>
<value>/WEB-INF/defs/administrator.xml</value>
<value>/WEB-INF/defs/customer.xml</value>
<value>/WEB-INF/defs/templates.xml</value>
</list>
</property>
</bean>
The preceding example defines five files that contain definitions. The files are all located in
the WEB-INF/defs
directory. At initialization of the WebApplicationContext
, the
files are loaded, and the definitions factory are initialized. After that has
been done, the Tiles included in the definition files can be used as views within your
Spring web application. To be able to use the views, you have to have a ViewResolver
as with any other view technology used with Spring. You can can use either of two
implementations, the UrlBasedViewResolver
and the ResourceBundleViewResolver
.
You can specify locale-specific Tiles definitions by adding an underscore and then the locale, as the following example shows:
<bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles3.TilesConfigurer">
<property name="definitions">
<list>
<value>/WEB-INF/defs/tiles.xml</value>
<value>/WEB-INF/defs/tiles_fr_FR.xml</value>
</list>
</property>
</bean>
With the preceding configuration, tiles_fr_FR.xml
is used for requests with the fr_FR
locale,
and tiles.xml
is used by default.
Note
|
Since underscores are used to indicate locales, we recommended not using them otherwise in the file names for Tiles definitions. |
The UrlBasedViewResolver
instantiates the given viewClass
for each view it has to
resolve. The following bean defines a UrlBasedViewResolver
:
<bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.tiles3.TilesView"/>
</bean>
The ResourceBundleViewResolver
has to be provided with a property file that contains
view names and view classes that the resolver can use. The following example shows a bean
definition for a ResourceBundleViewResolver
and the corresponding view names and view
classes (taken from the Pet Clinic sample):
<bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">
<property name="basename" value="views"/>
</bean>
...
welcomeView.(class)=org.springframework.web.servlet.view.tiles3.TilesView
welcomeView.url=welcome (this is the name of a Tiles definition)
vetsView.(class)=org.springframework.web.servlet.view.tiles3.TilesView
vetsView.url=vetsView (again, this is the name of a Tiles definition)
findOwnersForm.(class)=org.springframework.web.servlet.view.JstlView
findOwnersForm.url=/WEB-INF/jsp/findOwners.jsp
...
When you use the ResourceBundleViewResolver
, you can easily mix
different view technologies.
Note that the TilesView
class supports JSTL (the JSP Standard Tag Library).
As an advanced feature, Spring also supports two special Tiles PreparerFactory
implementations. See the Tiles documentation for details on how to use
ViewPreparer
references in your Tiles definition files.
You can specify SimpleSpringPreparerFactory
to autowire ViewPreparer
instances based on
specified preparer classes, applying Spring’s container callbacks as well as applying
configured Spring BeanPostProcessors. If Spring’s context-wide annotation configuration has
been activated, annotations in ViewPreparer
classes aree automatically detected and
applied. Note that this expects preparer classes in the Tiles definition files, as
the default PreparerFactory
does.
You can specify SpringBeanPreparerFactory
to operate on specified preparer names (instead
of classes), obtaining the corresponding Spring bean from the DispatcherServlet’s
application context. The full bean creation process is in the control of the Spring
application context in this case, allowing for the use of explicit dependency injection
configuration, scoped beans, and so on. Note that you need to define one Spring bean definition
for each preparer name (as used in your Tiles definitions). The following example shows
how to define a set a SpringBeanPreparerFactory
property on a TilesConfigurer
bean:
<bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles3.TilesConfigurer">
<property name="definitions">
<list>
<value>/WEB-INF/defs/general.xml</value>
<value>/WEB-INF/defs/widgets.xml</value>
<value>/WEB-INF/defs/administrator.xml</value>
<value>/WEB-INF/defs/customer.xml</value>
<value>/WEB-INF/defs/templates.xml</value>
</list>
</property>
<!-- resolving preparer names as Spring bean definition names -->
<property name="preparerFactoryClass"
value="org.springframework.web.servlet.view.tiles3.SpringBeanPreparerFactory"/>
</bean>
Both AbstractAtomFeedView
and AbstractRssFeedView
inherit from the
AbstractFeedView
base class and are used to provide Atom and RSS Feed views, respectively. They
are based on java.net’s ROME project and are located in the
package org.springframework.web.servlet.view.feed
.
AbstractAtomFeedView
requires you to implement the buildFeedEntries()
method and
optionally override the buildFeedMetadata()
method (the default implementation is
empty). The following example shows how to do so:
public class SampleContentAtomView extends AbstractAtomFeedView {
@Override
protected void buildFeedMetadata(Map<String, Object> model,
Feed feed, HttpServletRequest request) {
// implementation omitted
}
@Override
protected List<Entry> buildFeedEntries(Map<String, Object> model,
HttpServletRequest request, HttpServletResponse response) throws Exception {
// implementation omitted
}
}
Similar requirements apply for implementing AbstractRssFeedView
, as the following example shows:
public class SampleContentAtomView extends AbstractRssFeedView {
@Override
protected void buildFeedMetadata(Map<String, Object> model,
Channel feed, HttpServletRequest request) {
// implementation omitted
}
@Override
protected List<Item> buildFeedItems(Map<String, Object> model,
HttpServletRequest request, HttpServletResponse response) throws Exception {
// implementation omitted
}
}
The buildFeedItems()
and buildFeedEntries()
methods pass in the HTTP request, in case
you need to access the Locale. The HTTP response is passed in only for the setting of
cookies or other HTTP headers. The feed is automatically written to the response
object after the method returns.
For an example of creating an Atom view, see Alef Arendsen’s Spring Team Blog entry.
Spring offers ways to return output other than HTML, including PDF and Excel spreadsheets. This section describes how to use those features.
An HTML page is not always the best way for the user to view the model output, and Spring makes it simple to generate a PDF document or an Excel spreadsheet dynamically from the model data. The document is the view and is streamed from the server with the correct content type, to (hopefully) enable the client PC to run their spreadsheet or PDF viewer application in response.
In order to use Excel views, you need to add the Apache POI library to your classpath, For PDF generation, you need to add (preferably) the OpenPDF library.
Note
|
You should use the latest versions of the underlying document-generation libraries, if possible. In particular, we strongly recommend OpenPDF (for example, OpenPDF 1.0.5) instead of the outdated original iText 2.1.7, since OpenPDF is actively maintained and fixes an important vulnerability for untrusted PDF content. |
A simple PDF view for a word list could extend
org.springframework.web.servlet.view.document.AbstractPdfView
and implement the
buildPdfDocument()
method, as the following example shows:
public class PdfWordList extends AbstractPdfView {
protected void buildPdfDocument(Map<String, Object> model, Document doc, PdfWriter writer,
HttpServletRequest request, HttpServletResponse response) throws Exception {
List<String> words = (List<String>) model.get("wordList");
for (String word : words) {
doc.add(new Paragraph(word));
}
}
}
A controller can return such a view either from an external view definition
(referencing it by name) or as a View
instance from the handler method.
Since Spring Framework 4.2,
org.springframework.web.servlet.view.document.AbstractXlsView
is provided as a base
class for Excel views. It is based on Apache POI, with specialized subclasses (AbstractXlsxView
and AbstractXlsxStreamingView
) that supersede the outdated AbstractExcelView
class.
The programming model is similar to AbstractPdfView
, with buildExcelDocument()
as the central template method and controllers being able to return such a view from
an external definition (by name) or as a View
instance from the handler method.
Spring offers support for the Jackson JSON library.
The MappingJackson2JsonView
uses the Jackson library’s ObjectMapper
to render the response
content as JSON. By default, the entire contents of the model map (with the exception of
framework-specific classes) are encoded as JSON. For cases where the contents of the
map need to be filtered, you can specify a specific set of model attributes to encode
by using the modelKeys
property. You can also use the extractValueFromSingleKeyModel
property
to have the value in single-key models extracted and serialized directly rather than
as a map of model attributes.
You can customize JSON mapping as needed by using Jackson’s provided
annotations. When you need further control, you can inject a custom ObjectMapper
through the ObjectMapper
property, for cases where you need to provide custom JSON
serializers and deserializers for specific types.
MappingJackson2XmlView
uses the
Jackson XML extension’s XmlMapper
to render the response content as XML. If the model contains multiples entries, you should explicitly set the
object to be serialized by using the modelKey
bean property.
If the model contains a single entry, it is serialized automatically.
You can customized XML mapping as needed by using JAXB or Jackson’s provided
annotations. When you need further control, you can inject a custom XmlMapper
through the ObjectMapper
property, for cases where custom XML
you need to provide serializers and deserializers for specific types.
The MarshallingView
uses an XML Marshaller
(defined in the org.springframework.oxm
package) to render the response content as XML. You can explicitly set the object to be marshalled
by using a MarshallingView
instance’s modelKey
bean property. Alternatively, the view
iterates over all model properties and marshals the first type that is supported
by the Marshaller
. For more information on the functionality in the
org.springframework.oxm
package, see
Marshalling XML using O/X Mappers.
XSLT is a transformation language for XML and is popular as a view technology within web applications. XSLT can be a good choice as a view technology if your application naturally deals with XML or if your model can easily be converted to XML. The following section shows how to produce an XML document as model data and have it transformed with XSLT in a Spring Web MVC application.
This example is a trivial Spring application that creates a list of words in the
Controller
and adds them to the model map. The map is returned, along with the view
name of our XSLT view. See [mvc-controller] for details of Spring Web MVC’s
Controller
interface. The XSLT controller turns the list of words into a simple XML
document ready for transformation.
Configuration is standard for a simple Spring web application: The MVC configuration
has to define an XsltViewResolver
bean and regular MVC annotation configuration.
The following example shows how to do so:
@EnableWebMvc
@ComponentScan
@Configuration
public class WebConfig implements WebMvcConfigurer {
@Bean
public XsltViewResolver xsltViewResolver() {
XsltViewResolver viewResolver = new XsltViewResolver();
viewResolver.setPrefix("/WEB-INF/xsl/");
viewResolver.setSuffix(".xslt");
return viewResolver;
}
}
We also need a Controller that encapsulates our word-generation logic.
The controller logic is encapsulated in a @Controller
class, with the
handler method being defined as follows:
@Controller
public class XsltController {
@RequestMapping("/")
public String home(Model model) throws Exception {
Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
Element root = document.createElement("wordList");
List<String> words = Arrays.asList("Hello", "Spring", "Framework");
for (String word : words) {
Element wordNode = document.createElement("word");
Text textNode = document.createTextNode(word);
wordNode.appendChild(textNode);
root.appendChild(wordNode);
}
model.addAttribute("wordList", root);
return "home";
}
}
So far, we have only created a DOM document and added it to the Model map. Note that you
can also load an XML file as a Resource
and use it instead of a custom DOM document.
There are software packages available that automatically 'domify' an object graph, but, within Spring, you have complete flexibility to create the DOM from your model in any way you choose. This prevents the transformation of XML playing too great a part in the structure of your model data, which is a danger when using tools to manage the DOMification process.
Finally, the XsltViewResolver
resolves the “home” XSLT template file and merges the
DOM document into it to generate our view. As shown in the XsltViewResolver
configuration, XSLT templates live in the war
file in the WEB-INF/xsl
directory
and end with an xslt
file extension.
The following example shows an XSLT transform:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" omit-xml-declaration="yes"/>
<xsl:template match="/">
<html>
<head><title>Hello!</title></head>
<body>
<h1>My First Words</h1>
<ul>
<xsl:apply-templates/>
</ul>
</body>
</html>
</xsl:template>
<xsl:template match="word">
<li><xsl:value-of select="."/></li>
</xsl:template>
</xsl:stylesheet>
The preceding transform is rendered as the following HTML:
<html>
<head>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Hello!</title>
</head>
<body>
<h1>My First Words</h1>
<ul>
<li>Hello</li>
<li>Spring</li>
<li>Framework</li>
</ul>
</body>
</html>