Session Check Interceptor

There must be some way to check that the current session is valid or invalid. This can be done using interceptors in struts in a very easy way. Here I am giving an example how to resolve this. First of all we will make an interceptor named SessionCheck.java.

package com.demo.interceptors;

import java.util.Collections;
import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ActionProxy;
import com.opensymphony.xwork2.config.entities.ResultConfig;
import com.opensymphony.xwork2.interceptor.Interceptor;

public class SessionCheck implements Interceptor {

 public void init() {
 }

 public void destroy() {
 }

 public String intercept(ActionInvocation invocation) throws Exception {
  ActionProxy proxy;
  proxy = invocation.getProxy();
  Map session = ActionContext.getContext().getSession();
  Map results = proxy.getConfig().getResults();
 
   // We are checking that the user that is set at login time is null or
   // not
   
  if (session.get("user") != null) {
   return invocation.invoke();
  } else {
   
    // Here we are passing the result to an invalid page by specifying
    // its location
    
   ResultConfig rc = new ResultConfig("invalid", "org.apache.struts2.views.freemarker.FreemarkerResult",
     Collections.singletonMap("location", "/com/demo/interceptors/invalid.jsp"));
   results.put("invalid", rc);

   return "invalid";
  }

 }
}

Now in struts.xml put the following code

<?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>
 ...
 ...
 
 <interceptors>
  <interceptor name="SessionCheck" class="com.demo.interceptors.SessionCheck" />
 </interceptors>
 
 <!-- We are using this because we want it to apply for each and every action -->
 <default-interceptor-ref name="SessionCheck" />
    
 ...
 ...
</struts>