struts2 session拦截器

今天发现在用SessionFilter过滤session时发现servletResponse.sendRedirect(path+"/login.jsp");有时并不能跳转，可改用拦截器实现。
在struts.xml中增加：

 <!-- 定义一个author拦截器，并定义一个默认拦截器 -->
		<interceptors>  
            <interceptor name="authorLogin" class="com.rating.joyintech.action.AuthorizationInterceptor"/>
            <interceptor-stack name="myStack">  
               <interceptor-ref name="defaultStack"/>  
               <interceptor-ref name="authorLogin"/>  
            </interceptor-stack>  
        </interceptors>   
        <default-interceptor-ref name="myStack"/>
        <global-results> 
        	<result name="noSession">/login.jsp</result>
	    </global-results>

对应的拦截器代码如下:

package com.rating.joyintech.action;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts2.ServletActionContext;

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

public class AuthorizationInterceptor extends AbstractInterceptor{

	@Override
	public String intercept(ActionInvocation ai) throws Exception {
		// TODO Auto-generated method stub
		Map session = ai.getInvocationContext().getSession();
		HttpServletRequest request = ServletActionContext.getRequest();
		if(session.get("userInfo")==null && request.getRequestURI().indexOf("login")==-1){//login.action不拦截
			return "noSession";

		}else{
			return ai.invoke();
		}
	}


}