session失效后跳转到登陆页面

一、编写Filter拦截器类　

 1 package com.pv.utils;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.*;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import javax.servlet.http.HttpSession;
10 
11 public class RequestFilter implements Filter  {
12     private FilterConfig config;
13     //实现初始化方法
14     public void init(FilterConfig config){
15         this.config = config;
16     }
17     public void destroy(){
18         this.config = null;
19     }
20     
21     @Override
22     public void doFilter(ServletRequest req, ServletResponse res,
23             FilterChain chain) throws IOException, ServletException {
24         // TODO Auto-generated method stub
25         req.setCharacterEncoding("utf-8");        
26         HttpServletRequest request  = (HttpServletRequest) req;        
27         HttpServletResponse response  = (HttpServletResponse) res;
28         HttpSession session = request.getSession();
29         //获取客户请求的页面
30         String url = request.getServletPath();
31         System.out.println("wangming"+url);
32         if((!request.getServletPath().equals("/login.jsp"))
33             &&(!request.getServletPath().equals("/solar.jsp"))
34             &&(!request.getServletPath().equals("/index.jsp"))){
35             System.out.println(request.getServletPath());  
36             if(session.getAttribute("username")==null){
37                 session.invalidate();  
38                 response.setContentType("text/html;charset=gb2312");  
39                 PrintWriter out = response.getWriter();  
40                 out.println("<script language='javascript' type='text/javascript'>");  
41                 out.println("alert('由于你长时间没有操作,导致Session失效!请你重新登录!');top.location.href='" + request.getContextPath() + "/solar.jsp'");  
42                 out.println("</script>");  
43             }else{
44                 chain.doFilter(request , response );
45             }
46         }else{
47             chain.doFilter(request , response );
48         }        
49     }    
50 }

二、在web.xml中配置拦截器　　

 1 <session-config>
 2      <session-timeout>1</session-timeout>
 3 </session-config>
 4 
 5 <filter>
 6     <filter-name>RequestFilter</filter-name>
 7     <filter-class>com.pv.utils.RequestFilter</filter-class>
 8 </filter>
 9 <filter-mapping>
10     <filter-name>RequestFilter</filter-name>
11     <url-pattern>*.jsp</url-pattern>
12 </filter-mapping>