java web之Listener实现单态登录

来源：互联网发布：工业手持数据采集终端编辑：程序博客网时间：2024/05/24 06:18

废话不说，直接上代码！

登录与注销动作都在该JSP中完成。

<span style="font-size:18px;"><%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>   <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>   <%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>   <jsp:directive.page import="com.wang.singleton.PersonInfo"/>   <%   String action = request.getParameter("action");   String account = request.getParameter("account");   if("login".equals(action) && account.trim().length()>0){   PersonInfo personInfo = new PersonInfo();   personInfo.setAccount(account);   personInfo.setIp(request.getRemoteAddr());   personInfo.setLoginDate(new java.util.Date());      session.setAttribute("personInfo",personInfo);      response.sendRedirect(response.encodeRedirectURL(request.getRequestURI()));   return;   }   else if("logout".equals(action)){   session.removeAttribute("personInfo");   response.sendRedirect(response.encodeRedirectURL(request.getRequestURI()));   return;   }            %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><c:choose><c:when test="${ personInfo != null}">欢迎您,${personInfo.account}<br/>您的登录ip为,${personInfo.ip}<br>登录时将为,<fmt:formatDate value="${personInfo.loginDate}" pattern="yyyy-MM-dd HH:mm"/><br/><a href="${pageContext.request.requestURI}?action=logout">退出</a><!-- 每五秒钟刷新一次页面 --><script>setTimeout("location=location;", 5000);</script></c:when><c:otherwise>${msg}<c:remove var="msg" scope="session"/><form action="${pageContext.request.requestURI}?action=login" method="post">账号:<input name="account"><input type="submit" value="登录"></form></c:otherwise></c:choose></body></html></span>

personInfo java bean

package com.wang.singleton;import java.io.Serializable;import java.util.Date;public class PersonInfo implements Serializable{private static final long serialVersionUID = 1L;private String account;private String ip;private Date loginDate;public String getAccount() {return account;}public void setAccount(String account) {this.account = account;}public String getIp() {return ip;}public void setIp(String ip) {this.ip = ip;}public Date getLoginDate() {return loginDate;}public void setLoginDate(Date loginDate) {this.loginDate = loginDate;}public boolean equals(Object obj){if(obj == null || !(obj instanceof PersonInfo)){return false;}return account.equalsIgnoreCase(((PersonInfo) obj).getAccount());}}

以下Listener用于实现单态登录

package com.wang.singleton;import java.util.HashMap;import java.util.Map;import javax.servlet.http.HttpSession;import javax.servlet.http.HttpSessionAttributeListener;import javax.servlet.http.HttpSessionBindingEvent;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;public class LoginSessionListener implements <strong>HttpSessionAttributeListener</strong> {   Log log= LogFactory.getLog(this.getClass());      Map<String,HttpSession> map = new HashMap<String,HttpSession>();    public LoginSessionListener() {        // TODO Auto-generated constructor stub    }    public void attributeRemoved(HttpSessionBindingEvent event)  {          // 删除属性前被调用    String name  = event.getName();    if(name.equals("personInfo")){    PersonInfo personInfo = (PersonInfo) event.getValue();    map.remove(personInfo.getAccount());    log.info("账号"+personInfo.getAccount()+"注销");    }    }    public void attributeAdded(HttpSessionBindingEvent event)  {          // 添加session时被调用    String name = event.getName();    if(name.equals("personInfo")){    PersonInfo personInfo = (PersonInfo) event.getValue();    if(map.get(personInfo.getAccount()) != null){    HttpSession session = map.get(personInfo.getAccount());        PersonInfo oldPersonInfo = (PersonInfo) session.getAttribute("personInfo");    log.info("账号"+oldPersonInfo.getAccount()+"在"+oldPersonInfo.getIp()+"已经登录，该登录将被迫下线！");    session.removeAttribute("personInfo");    session.setAttribute("msg", "您的账号已经在其他机器上登录,您被迫下线！");        }    map.put(personInfo.getAccount(), event.getSession());    log.info("账号"+personInfo.getAccount()+"在"+personInfo.getIp()+"登录");        }    }    public void attributeReplaced(HttpSessionBindingEvent event)  {          // 修改属性时被调用    String name = event.getName();    if(name.equals("personInfo")){    PersonInfo oldPersonInfo = (PersonInfo) event.getValue();    //移除旧的登录信息    map.remove(oldPersonInfo.getAccount());    //新的登录信息    PersonInfo personInfo = (PersonInfo) event.getSession().getAttribute("personInfo");    //也要检查新的账号是否在别的机器上登录    if(map.get(personInfo.getAccount()) != null){    HttpSession session = map.get(personInfo.getAccount());        session.removeAttribute("personInfo");    session.setAttribute("msg", "您的账号已经在其他机器上登录,您被迫下线！");        }    map.put(personInfo.getAccount(), event.getSession());    log.info("账号"+personInfo.getAccount()+"在"+personInfo.getIp()+"登录");        }    }}

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">  <display-name>loginListener</display-name>  <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.htm</welcome-file>    <welcome-file>index.jsp</welcome-file>    <welcome-file>default.html</welcome-file>    <welcome-file>default.htm</welcome-file>    <welcome-file>default.jsp</welcome-file>  </welcome-file-list>  <listener>    <listener-class>com.wang.singleton.LoginSessionListener</listener-class>  </listener></web-app>

注意：本例中Listener与登录模块等没有代码耦合。

源代码地址：http://download.csdn.net/detail/wangxuewei111/8530549

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