Struts 2 and springs Integration

In this simple hello world example you will see how to integrate Spring and Struts 2 using the struts2-spring-plugin. By doing this you can utilize the Spring's powerful Dependency Injection feature. To learn more about Dependency Injection refer this example.

Step1:

First add the org.springframework.web.context.ContextLoaderListener to the web.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
 <display-name>Struts2Example14</display-name>
    <!-- Context Configuration locations for Spring XML files -->
<context-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>/WEB-INF/applicationContext-*.xml,classpath*:applicationContext-*.xml</param-value>
</context-param>

   <filter>
       <filter-name>struts2</filter-name>
       <filter-class>org.apache.struts2.dispatcher.ng.filter.    StrutsPrepareAndExecuteFilter</filter-class>
   </filter>
   <listener>
       <listener-class>org.springframework.web.context. ContextLoaderListener</listener-class>
   </listener>
   <filter-mapping>
       <filter-name>struts2</filter-name>
      <url-pattern>/*</url-pattern>
   </filter-mapping>
   <welcome-file-list>
       <welcome-file>index.jsp</welcome-file>
   </welcome-file-list>
</web-app>

Step2:

By default the applicationContext.xmll file will be used for doing the Spring bean configuration.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
   <bean id="helloWorldClass" class="com.net.champ.HelloWorld">
       <property name="message" value="Hello World!">
   </bean>
</beans>

As you can see we have registered the HelloWorld class and injected the "Hello World!" message to the message attribute using the setter injection method.

Step3:

All the Struts 2 action configuration goes in the struts.xml file.

<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

   <constant name="struts.objectFactory"
value="org.apache.struts2.spring.StrutsSpringObjectFactory"/>

   <package name="default" extends="struts-default">
       <action name="helloWorld" class="helloWorldClass">
           <result name="SUCCESS">/success.jsp</result>
       </action>
   </package>
</struts>

The only change here is instead of referring the com.net.champ.HelloWorld class directly, we relate it using the bean name given in the spring bean configuration file.

Step4:

The HelloWorld class is shown below. In the execute() method we simply return "SUCCESS" and the message attribute is set using setter injection.

package com.net.champ;

public class HelloWorld {

   private String message;

   public String getMessage() {
       return message;
   }

   public void setMessage(String message) {
       this.message = message;
   }
 
   public String execute() {
       return "SUCCESS";
   }
}

Step5:

In the index.jsp page we forward the request to the helloWorld action.
meta equiv="Refresh" content="0;URL=helloWorld.action"
You need to have the following jar files in the WEB-INF/lib directory.
01. commons-fileupload-1.2.1
02. commons-io-1.3.2
03. commons-logging-1.1
04. freemarker-2.3.13
05. junit-3.8.1
06. ognl-2.6.11
07. struts2-convention-plugin-2.1.6
08. struts2-core-2.1.6
09. xwork-2.1.2
10. struts2-spring-plugin-2.1.6
11. antlr-runtime-3.0
12. org.springframework.asm-3.0.0.M3
13. org.springframework.beans-3.0.0.M3
14. org.springframework.context-3.0.0.M3
15. org.springframework.core-3.0.0.M3
16. org.springframework.expression-3.0.0.M3
17. org.springframework.web-3.0.0.M3
18. org.springframework.web.servlet-3.0.0.M3