Ajax Session失效跳转登录页面的方法

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

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

//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"));
}
}
});

也就是ajax发送请求时如果拦截返回一个表示就跳转，否则执行正常操作。