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Barebones Spring MVC Part 2: Annotation Configuration

This article is part of the Barebones Spring MVC series.

In Part 1: Core I showed how to create a very simple, but functional, web application based on Spring MVC. With the integration of Spring JavaConfig into Spring 3.0 core, it is now possible to build the same application without any XML-based Spring configuration.

The following changes are required:

1. Remove the XML-based Spring configuration, springmvc-servlet.xml.
2. Create an annotation-based Spring configuration, SimpleContext.java.
3. Replace the implicit XmlWebApplicationContext in the deployment descriptor with Spring's annotation-aware AnnotationConfigWebApplicationContext.

First, the XML-based Spring configuration is removed.

springmvc-servlet.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
  xmlns:mvc="http://www.springframework.org/schema/mvc"
  xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

  <mvc:annotation-driven />

  <bean
    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/jsp/" />
    <property name="suffix" value=".jsp" />
  </bean>

  <context:component-scan base-package="com.earldouglas.example.springmvc.web" />

</beans>

Next, the annotation-based Spring configuration is created.

SimpleContext.java:

package com.earldouglas.example.springmvc.web;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
public class SimpleContext {

  @Bean
  public DefaultAnnotationHandlerMapping defaultAnnotationHandlerMapping() {
    return new DefaultAnnotationHandlerMapping();
  }

  @Bean
  public InternalResourceViewResolver internalResourceViewResolver() {
    InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
    viewResolver.setPrefix("/WEB-INF/jsp/");
    viewResolver.setSuffix(".jsp");
    return viewResolver;
  }

  @Bean
  public SimpleController simpleController() {
    return new SimpleController();
  }
}

Finally, the deployment descriptor is updated.

Old web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  version="2.5">

  <servlet>
    <servlet-name>spring-mvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>spring-mvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>

New web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  version="2.5">

  <servlet>
    <servlet-name>spring-mvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextClass</param-name>
      <param-value>
        org.springframework.web.context.support.AnnotationConfigWebApplicationContext
            </param-value>
    </init-param>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>com.earldouglas.example.springmvc.web.SimpleContext</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>spring-mvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>

That's all there is to it!