Struts2 AJAX请求 Session失效处理

在Struts应用中，我们发出的请求都会经过 相应的拦截器进行相关处理，一般都会有一个用户登录拦截（Session失效拦截）；一般请求的话，如果Session失效时，我们会跳到登录页面，可是如果我们采用AJAX请求时，将会返回登录页面的HTML代码，这肯定不是我们想要的，那么我们如何解决呢？请看以下步骤：
一、建立拦截器

Java代码 
package com.xxx.planeap.interceptor; 
 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
import org.apache.log4j.Logger; 
import org.apache.struts2.ServletActionContext; 
 
import com.opensymphony.xwork2.ActionContext; 
import com.opensymphony.xwork2.ActionInvocation; 
import com.opensymphony.xwork2.ActionSupport; 
import com.opensymphony.xwork2.interceptor.AbstractInterceptor; 
import com.xxx.common.contants.ConstantsKey; 
import com.xxx.common.contants.SessionKey; 
import com.xxx.planeap.domain.User; 
import com.xxx.planeap.security.SecurityContextUtil; 
 
/**
* 
* @author Goma [e-mail]
* @version v1.0
* @since 2012-05-31
 
* 
*/ 
public class SecurityInterceptor extends AbstractInterceptor { 
    private static final long serialVersionUID = 1L; 
    private Logger logger = Logger.getLogger(SecurityInterceptor.class); 
 
    @Override 
    public String intercept(ActionInvocation invocation) throws Exception { 
        // TODO Auto-generated method stub 
 
        String className = invocation.getAction().getClass().getName(); 
        String action = className.substring(className.lastIndexOf(".")+1,className.length()); 
        String actionName = invocation.getProxy().getActionName(); 
         
        String result; 
        HttpServletRequest request = ServletActionContext.getRequest(); 
        HttpServletResponse response = ServletActionContext.getResponse(); 
        String type = request.getHeader("X-Requested-With"); 
        User user = (User) ActionContext.getContext().getSession().get(SessionKey.CURRENT_USER); 
        if (user == null) { 
            logger.debug("SECURITY CHECKED: NEED TO LOGIN"); 
            if ("XMLHttpRequest".equalsIgnoreCase(type)) {// AJAX REQUEST PROCESS 
                response.setHeader("sessionstatus", ConstantsKey.MSG_TIME_OUT); 
                result = null; 
            } else {// NORMAL REQUEST PROCESS 
                result = ActionSupport.LOGIN; 
            } 
        } else { 
            logger.debug("SECURITY CHECKED: USER HAS LOGINED"); 
            SecurityContextUtil.setCurrentUser(user); 
            boolean hanPerm = SecurityContextUtil.hasPerm(action, actionName); 
            logger.debug("SECURITY CHECKED: PERMISSION---"+action+"."+actionName+"="+hanPerm); 
            result = invocation.invoke(); 
        } 
        return result; 
    } 
} 


二、定义全局AJAX请求结束处理方法

Js代码 
//全局的AJAX访问，处理AJAX清求时SESSION超时 
$.ajaxSetup({ 
    contentType:"application/x-www-form-urlencoded;charset=utf-8", 
    complete:function(XMLHttpRequest,textStatus){ 
          //通过XMLHttpRequest取得响应头，sessionstatus            
          var sessionstatus=XMLHttpRequest.getResponseHeader("sessionstatus");  
          if(sessionstatus=="timeout"){ 
               //这里怎么处理在你，这里跳转的登录页面 
               window.location.replace(PlanEap.getActionURI("login")); 
       } 
    } 
});