Integrating Spring with Struts 2

To integrate Struts 2 and Spring, get and include the "struts2-spring-plugin-xxx.jar" library into your project classpath.

Dependency libraries :

• Struts 2 = struts2-core 2.1.8
• Spring framework = spring 2.5.6, spring-web 2.5.6
• Struts 2 + Spring plugins = struts2-spring-plugin 2.1.8

Spring Listener

Configure the Spring listener "org.springframework.web.context.ContextLoaderListener" in web.xml file.

web.xml

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>

<display-name>Struts 2 Web Application</display-name>

<filter>

  <filter-name>struts2</filter-name>

  <filter-class> 

 org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter 

  </filter-class>

</filter>

<filter-mapping>

  <filter-name>struts2</filter-name>

  <url-pattern>/*</url-pattern>

</filter-mapping>

<listener>

  <listener-class>

   org.springframework.web.context.ContextLoaderListener 

  </listener-class>

</listener>

</web-app>

Spring Bean

Register all the Spring’s Beans in the applicationContext.xml file, the Spring listener will locate this xml file automatically.

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<bean id="userBo" class="com.genius.user.bo.impl.UserBoImpl" />

<bean id="userSpringAction" 

      class="com.genius.user.action.UserSpringAction">

  <property name="userBo" ref="userBo" />

</bean>

</beans>

UserBo.java

package com.genius.user.bo;

public interface UserBo {

  public void printUser();

}

UserBoImpl.java

package com.genius.user.bo.impl;

import com.genius.user.bo.UserBo;

public class UserBoImpl implements UserBo{

  public void printUser(){

    System.out.println("printUser() is executed...");

  }

}

Struts Action and configuration

UserSpringAction.java

package com.genius.user.action;

import com.genius.user.bo.UserBo;

public class UserSpringAction{

  // DI via Spring

  UserBo userBo;

  public UserBo getUserBo() {

    return userBo;

  }

  public void setUserBo(UserBo userBo) {

    this.userBo = userBo;

  }

  public String execute() throws Exception {

   userBo.printUser();

   return "success";

  }

}

Struts.xml

Declared all the relationship here.

<?xml version="1.0" encoding="UTF-8" ?>

<!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.devMode" value="true" />

 <package name="default" namespace="/" extends="struts-default">

   <action name="userAction" 

           class="com.genius.user.action.UserAction" >

     <result name="success">pages/user.jsp</result>

   </action>

   <action name="userSpringAction" class="userSpringAction" >

     <result name="success">pages/user.jsp</result>

   </action>

 </package>

</struts>

Demo

Now, all the Struts 2 and Spring integration work is done, now see the following use case to access the Spring’s “userBo” bean.

Case 1 : Make Spring act as the Struts 2 Action class, and access the Spring’s bean.

In this example, the userSpringAction is act as the Struts 2 Action class, and you can DI the Spring’s userBo bean with normal Spring’s way.

struts.xml

<action name="userSpringAction" class="userSpringAction" >

   <result name="success">pages/user.jsp</result>

</action>

applicationContext.xml

<bean id="userSpringAction" 

      class="com.genius.user.action.UserSpringAction">

   <property name="userBo" ref="userBo" />

</bean>

To access this action, use the URL : http://localhost: 8080/Struts2Example/userSpringAction

Case 2 : Access the Spring’s bean in Struts 2 Action class.

By default, Spring listener enables “autowiring by matching the bean name“. So, it will pass the Spring’s “userBo” bean into the UserAction via setUserBo() automatically. See below Struts 2 Action : 

The Spring’s autowiring feature can change to name(default), type, auto or constructor, you may need to consult this Struts 2 Spring plugin documentation.

UserAction.java

package com.genius.user.action;

import com.genius.user.bo.UserBo;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction extends ActionSupport{

  // DI via Spring

  UserBo userBo;

  public UserBo getUserBo() {

    return userBo;

  }

  public void setUserBo(UserBo userBo) {

    this.userBo = userBo;

  }

  public String execute() throws Exception {

    userBo.printUser();

    return SUCCESS;

  }

}

To access this action, use the URL : http://localhost:8080/Struts2Example/userAction

WebApplicationContextUtils

Alternatively, you can use the Spring’s generic WebApplicationContextUtils class to get the Spring’s bean directly.

package com.genius.user.action;

import org.apache.struts2.ServletActionContext;

import org.springframework.web.context.WebApplicationContext;

import org.springframework.web.context.support.WebApplicationContextUtils;

import com.genius.user.bo.UserBo;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction extends ActionSupport{

  public String execute() throws Exception {

    WebApplicationContext context = 

      WebApplicationContextUtils.getRequiredWebApplicationContext 

      (ServletActionContext.getServletContext());

    UserBo userBo1 = (UserBo) context.getBean("userBo");

    userBo1.printUser();

    return SUCCESS;

  }

}

Reference