Spring Boot reduced lots of spring configuration and kick o fast development. Spring Boot offers a new paradigm for developing Spring applications with minimal friction. With Spring Boot, you’ll be able to develop Spring applications with more agility and be able to focus on addressing your application’s functionality needs with minimal.
Spring Boot is well suited for web application development. You can easily create a self-contained HTTP server using embedded Tomcat, Jetty, or Undertow. Most web applications will use the spring-boot-starter-web module to get up and running quickly.
Spring Web MVC framework
MVC stands for Model, View, Controller. The MVC design pattern is probably the most popular design pattern used when writing code to generate dynamic web content.
- Model refers to a data model, or some type of data structure.
- The view layer, in Java frequently a JSP. This will take data from the Model and render the view.
- Spring MVC lets you create special @Controller or @RestController beans to handle incoming HTTP requests. Methods in your controller are mapped to HTTP using @RequestMapping annotations.
Spring MVC auto-configuration
Spring Boot provides auto-configuration for Spring MVC. There are following features for auto-configuration for Spring MVC.
- Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.
- Support for serving static resources, including support for WebJars. By default Spring Boot will serve static content from a directory called /static (or /public or /resources or /META-INF/resources) in the classpath or from the root of the ServletContext. It uses the ResourceHttpRequestHandler from Spring MVC so you can modify that behavior by adding your own WebMvcConfigurerAdapter and overriding the addResourceHandlers method. Any resources with a path in /webjars/** will be served from jar files if they are packaged in the Webjars format.
- Automatic registration of Converter, GenericConverter, Formatter beans.
- Support for HttpMessageConverters. Spring MVC uses the HttpMessageConverter interface to convert HTTP requests and responses.
- Automatic registration of MessageCodesResolver. Spring MVC has a strategy for generating error codes for rendering error messages from binding errors: MessageCodesResolver
- Static index.html support. If you do this the default welcome page detection will switch to your custom locations, so if there is an index.html in any of your locations on startup, it will be the home page of the application.
- Custom Favicon support.
- Automatic use of a ConfigurableWebBindingInitializer bean. Spring MVC uses a WebBindingInitializer to initialize a WebDataBinder for a particular request. If you create your own ConfigurableWebBindingInitializer @Bean, Spring Boot will automatically configure Spring MVC to use it.
- When you’re using one of these templating engines (thymeleaf, freemarker, velocity, Groovy etc.) with the default configuration, your templates will be picked up automatically from src/main/resources/templates.
- Error Handling Spring Boot provides an /error mapping by default that handles all errors in a sensible way, and it is registered as a ‘global’ error page in the servlet container. For machine clients it will produce a JSON response with details of the error, the HTTP status and the exception message. For browser clients there is a ‘whitelabel’ error view that renders the same data in HTML format. If you want to display a custom HTML error page for a given status code, you add a file to an /error folder. Error pages can either be static HTML (i.e. added under any of the static resource folders) or built using templates. The name of the file should be the exact status code or a series mask.
- Spring Boot includes support for embedded Tomcat, Jetty, and Undertow servers. Most developers will simply use the appropriate ‘Starter’ to obtain a fully configured instance. By default the embedded server will listen for HTTP requests on port 8080.
- Any Servlet, Filter or Servlet *Listener instance that is a Spring bean will be registered with the embedded container. This can be particularly convenient if you want to refer to a value from your application.properties during configuration.
- By default, if the context contains only a single Servlet it will be mapped to /. In the case of multiple Servlet beans the bean name will be used as a path prefix. Filters will map to /*.
- EmbeddedWebApplicationContext The EmbeddedWebApplicationContext is a special type of WebApplicationContext that bootstraps itself by searching for a single EmbeddedServletContainerFactory bean.
Customizing embedded servlet containers
Common servlet container settings can be configured using Spring Environment properties. Usually you would define the properties in your application.properties file.
- Network settings: listen port for incoming HTTP requests (server.port), interface address to bind to server.address, etc.
- Session settings: whether the session is persistent (server.session.persistence), session timeout (server.session.timeout), location of session data (server.session.store-dir) and session-cookie configuration (server.session.cookie.*).
- Error management: location of the error page (server.error.path), etc.