Struts2 Custom Interceptor Example, Struts2 Interceptors

Let us see how to create user defined interceptors in struts2, we already know this fact that struts2 by default provided lot of interceptors. In fact we no need to create any custom interceptors , but this is the way to create custom interceptors if you would like to.

Let us see the steps to create our own interceptor

• Create one java class which should implements from Interceptor interface, see all interceptors in struts2 must implements from Interceptor interface only
• Override all abstract methods in Interface interface, Interceptor contains 3 abstract methods init(), destroy(), intercept(ActionInvocation inv)
• Finally configure our interceptor class in struts.xml file that’s it, let us see the example

Struts2 Custom Interceptor Example

Required files…

• index.jsp
• success.jsp
• web.xml
• struts.xml
• LogingEx.java
• MyInterceptor.java

Directory Structure

index.jsp

<META HTTP-EQUIV="Refresh" CONTENT="0;URL=verify.action">

success.jsp

<%@ taglib prefix="s" uri="/struts-tags" %>

Struts 2 Interceptors executed successfully, <br>
you can find the same in console.

LogingEx.java

package java4s;
import com.opensymphony.xwork2.ActionSupport;

public class LogingEx extends ActionSupport{
    private static final long serialVersionUID = 1L;    

    public String execute()
    {
        System.out.println("In action class execute method...!!");

        try
        {
           Thread.sleep(4000);
        } catch(Exception e)
        {

        }        

        return SUCCESS;
    }

}

MyInterceptor.java

package java4s;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

public class MyInterceptor implements Interceptor{
    private static final long serialVersionUID = 1L;    

    public void init()
    {
        System.out.println("Interceptor init method called.....");
    }

    public void destroy()
    {
        System.out.println("Interceptor destroy method called.....");
    }

    public String intercept(ActionInvocation inv) throws Exception
    {
        System.out.println("This is before invocation.invoke()...");

        String a = inv.invoke();

        System.out.println("This is after invocation.invoke()...");
        // here string a contains "success"
        return a;
    }

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi: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">
  <filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
  </filter>
  <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>

struts.xml

<?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>
    <include file="struts-default.xml"/>
    <package name="a" extends="struts-default">

    <interceptors>    

                 <interceptor name="myOwn" class="java4s.MyInterceptor"></interceptor>

                 <interceptor-stack name="dummyName">
                       <interceptor-ref name="myOwn"/>
                 </interceptor-stack>

    </interceptors>

        <action name="verify" class="java4s.LogingEx">
        <interceptor-ref name="dummyName"/>
        <result name="success">/success.jsp</result>
        </action>

    </package>
</struts>

Output

Note:
In MyInterceptor.java, line number 23 we are calling invoke() method of ActionInvocation. Actually invoke() method will take cares the total journey of executing pre-post logic for our Action class.

What you are thinkig....