使用(Filter)过虑器实现对Session是否过时的判断

使用(Filter)过虑器实现对Session是否过时的判断
 
 
在开发时,在第个页面,或者BaseAction对Session是否超时正行判断,但随着项目越来越来.页面很的时候写起来会觉得烦,由于项目需要最近做了一个这样的例子。

    web.xml文件内容如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <filter>
     <filter-name>sf</filter-name>
     <filter-class>com.pdw.websystem.SessionFilterImpl</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>sf</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <init-param>
      <param-name>debug</param-name>
      <param-value>3</param-value>
    </init-param>
    <init-param>
      <param-name>detail</param-name>
      <param-value>3</param-value>
    </init-param>
    <load-on-startup>0</load-on-startup>
  </servlet>

  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  <session-config>
   <session-timeout>2</session-timeout>
  </session-config>
  <listener>
   <listener-class>com.pdw.websystem.SessionListenerImpl</listener-class>
  </listener>
</web-app>

SessionFilterImpl.java文件如下：

package com.pdw.websystem;


import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.UnavailableException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class SessionFilterImpl implements Filter ...{


    protected String encoding = null;


    protected FilterConfig filterConfig = null;


    protected boolean ignore = true;

    public void destroy() ...{

        this.encoding = null;
        this.filterConfig = null;

    }


    /** *//**
     * Select and set (if specified) the character encoding to be used to
     * interpret request parameters for this request.
     *
     * @param request The servlet request we are processing
     * @param result The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
 throws IOException, ServletException ...{
    
     HttpServletRequest hrequest=(HttpServletRequest)request;
     HttpServletResponse hresponse=(HttpServletResponse)response;
     HttpSession session=hrequest.getSession();
     if(session.getAttribute("name")==null)...{
      hresponse.sendRedirect("logon.jsp");
     }
        chain.doFilter(request, response);

    }


    /** *//**
     * Place this filter into service.
     *
     * @param filterConfig The filter configuration object
     */
    public void init(FilterConfig filterConfig) throws ServletException ...{

    }
}

 

使可轻松实现对Session是否超时的判断