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>