Checkout the code: https://github.com/sparso/spring-javaconfig-examples (look at spring-barebones-javaconfig).
Main Components
Web Application: The term for a collection of servlets packaged in a war file.
ServletContext: Defines methods to talk to the servlet container (eg Tomcat).
ApplicationContext: Defines methods to access Spring Beans etc.
WebApplicationContext: Extends the above, adds a getServletContext() method.
AnnotationConfigApplicationContext: implementation of the above which accepts annotated classes as input rather than XML.
ContextLoaderListener: Creates the application context. Ties the lifecycle of the ApplicationContext to the lifecycle of the ServletContext.
DispatcherServlet: Takes an incoming request, delegates handling of it to a controller.
Maven
spring-framework-bom: Sets version numbers of spring modules so we don't have to.
spring-core, spring-webmvc, spring-web: Minimal dependencies for a REST API.
javax.servlet-api: So we can deploy our module in Tomcat.
maven-war-plugin: Build the war and set failOnMissingWebXml to false.
WebApplicationInitializer
You implement this interface in order to configure the ServletContext programatically.
Option 1: Implement it yourself
The following code shows you how to bootstrap the container yourself. It:
- Creates the root ApplicationContext (where spring beans live)
- Attaches a ContextLoaderListener to it (connecting it to the servlet lifecycle)
- Creates a DispatcherServlet to router HTTP requests to your app.
- Adds your Java Config classes to each step.
Option 2: Use an AbstractAnnotationConfigDispatcherServletInitializer
This gets rid of most of the boilerplate code:
Context Configuration
Here's my context configuration, documentation in the comments:
REST Controller
Finally here's the controller:
