session失效后跳转到登陆页面

一、编写Filter拦截器类　

 package com.pv.utils;

 import java.io.IOException;
 import java.io.PrintWriter;

 import javax.servlet.*;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 public class RequestFilter implements Filter  {
     private FilterConfig config;
     //实现初始化方法
     public void init(FilterConfig config){
         this.config = config;
     }
     public void destroy(){
         this.config = null;
     }

     @Override
     public void doFilter(ServletRequest req, ServletResponse res,
             FilterChain chain) throws IOException, ServletException {
         // TODO Auto-generated method stub
         req.setCharacterEncoding("utf-8");
         HttpServletRequest request  = (HttpServletRequest) req;
         HttpServletResponse response  = (HttpServletResponse) res;
         HttpSession session = request.getSession();
         //获取客户请求的页面
         String url = request.getServletPath();
         System.out.println("wangming"+url);
         if((!request.getServletPath().equals("/login.jsp"))
             &&(!request.getServletPath().equals("/solar.jsp"))
             &&(!request.getServletPath().equals("/index.jsp"))){
             System.out.println(request.getServletPath());
             if(session.getAttribute("username")==null){
                 session.invalidate();
                 response.setContentType("text/html;charset=gb2312");
                 PrintWriter out = response.getWriter();
                 out.println("<script language='javascript' type='text/javascript'>");
                 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'");
                 out.println("</script>");
             }else{
                 chain.doFilter(request , response );
             }
         }else{
             chain.doFilter(request , response );
         }
     }
 }

二、在web.xml中配置拦截器　　

 <session-config>
      <session-timeout>1</session-timeout>
 </session-config>

 <filter>
     <filter-name>RequestFilter</filter-name>
     <filter-class>com.pv.utils.RequestFilter</filter-class>
 </filter>
 <filter-mapping>
     <filter-name>RequestFilter</filter-name>
     <url-pattern>*.jsp</url-pattern>
 </filter-mapping>