Struts 2 + Spring Integration Example

In this tutorial, it shows the integration between Struts 2 and Spring.

1. Project Structure

Here’s the project folder structure of this tutorials.

2. Struts 2 + Spring Plugin

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

pom.xml

        <!-- Struts 2 -->
        <dependency>
                <groupId>org.apache.struts</groupId>
         <artifactId>struts2-core</artifactId>
         <version>2.1.8</version>
        </dependency>
 
 <!-- Spring framework --> 
 <dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring</artifactId>
  <version>2.5.6</version>
 </dependency>
 
 <dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-web</artifactId>
  <version>2.5.6</version>
 </dependency>
 
 <!-- Struts 2 + Spring plugins -->
 <dependency>
                 <groupId>org.apache.struts</groupId>
          <artifactId>struts2-spring-plugin</artifactId>
          <version>2.1.8</version>
         </dependency>

3. 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>

3. Register 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.mkyong.user.bo.impl.UserBoImpl" />
 
 <bean id="userSpringAction" class="com.mkyong.user.action.UserSpringAction">
  <property name="userBo" ref="userBo" /> 
 </bean>
 
</beans>

UserBo.java

package com.mkyong.user.bo;
 
public interface UserBo{
 
 public void printUser();
 
}

UserBoImpl.java

package com.mkyong.user.bo.impl;
 
import com.mkyong.user.bo.UserBo;
 
public class UserBoImpl implements UserBo{
 
 public void printUser(){
  System.out.println("printUser() is executed...");
 }
 
}

UserSpringAction.java

package com.mkyong.user.action;
 
import com.mkyong.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";
 
 }
}

5. 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.mkyong.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>

6. 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.
• Case 2 : Access the Spring’s bean in Struts 2 Action class.

Case 1

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.mkyong.user.action.UserSpringAction">
 <property name="userBo" ref="userBo" /> 
</bean>

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

Case 2

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.mkyong.user.action;
 
import com.mkyong.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.mkyong.user.action;
 
import org.apache.struts2.ServletActionContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
 
import com.mkyong.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;
 
 }
}

A really long and tedious article, make sure you download the full project source code for practice.