Spring Boot will automatically configure a web application when it finds the classes on the classpath. It will also start an embedded server (by default it will launch an embedded Tomcat).
Problem
How to use Spring Boot to power a Spring MVC application?
Solution
Spring Boot will do auto-configuration for the components needed for Spring MVC. To enable this, Spring Boot needs to be able to detect the Spring MVC classes on its classpath. For this, the spring-boot-starter-web needs to be added as a dependency.
Problem
How to use Spring MVC to expose REST based resources @WebMvcTest.
Solution
A JSON library is needed to do the JSON marshalling (although XML and other formats could be used as well, as content negotiation 3 is part of REST). The spring-boot-starter-web dependency already includes the needed Jackson libraries by default.
Problem
How to use Thymeleaf to render the pages of the application?
Solution
The dependency for Thymeleaf needs to be added and a regular @Controller has to be created to determine the view and fill the model.
Problem
How to customize the default white label error page shown by Spring Boot.
Solution
An additional error.html must be added as a customized error page, or specific error pages for specific HTTP error codes (i.e., 404.html and 500.html).
Problem
When developing an internationalized web application, the web pages have to be displayed in a user’s preferred locale. It's never wanted to create different versions of the same page for different locales.
Solution
To avoid creating different versions of a page for different locales, the web pages should be made independent of the locale by externalizing locale-sensitive text messages. Spring is able to resolve text messages by using a message source, which has to implement the MessageSource interface. In the page templates it can be used either special tags or do lookups for the messages.
Problem
In order for a web application to support internationalization, each user’s preferred locale must be identified and display contents according to this locale.
Solution
In a Spring MVC application, a user’s locale is identified by a locale resolver, which has to implement the LocaleResolver interface. Spring MVC comes with several LocaleResolver implementations for you to resolve locales by different criteria. Alternatively, an own custom locale resolver may be created by implementing that interface.
Spring Boot allows to set the spring.mvc.locale-resolver property. This can be set to ACCEPT (the default) or FIXED. The first will create an AcceptHeaderLocaleResolver; the latter, a FixedLocaleResolver. It can be also defined a locale resolver by registering a bean of type LocaleResolver in the web application context. The bean name of the locale resolver must set to localeResolver so it can be autodetected.
Problem
How to use Jetty as an embedded container instead of the default Tomcat container.
Solution
The Tomcat runtime must be excluded and the Jetty runtime must be included. Spring Boot will automatically detect if Tomcat, Jetty, or Undertow is on the classpath and configure the container accordingly.
Problem
How to make the application to be accessible through HTTPS next (or instead of ) HTTP.
Solution
A certificate has to be placed in a keystore, and using the server.ssl namespace, the keystore must be configured. Spring Boot will then automatically configure the server to be accessible through HTTPS only.