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前台
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<script type="text/javascript">
window.onunload =function(){
}
</script>
<body>
<form action="Login?zhang=login" method="post">
<ul>
<li>用户名：<input type="text" name="userName"/></li>
<li><input type="submit" value="登陆"/></li>
<li><a href="Login?zhang=logout">用户注销</a></li>
</ul>
<ul>
<li>当前在线用户</li>
<c:forEach items="${userList}" var="userList">
<li>${userList }</li>
</c:forEach>
</ul>
</form>
</body>
</html>
监听器
package com.greendog.jiantingqi;
import java.util.ArrayList;
import java.util.List;
import javax.Servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
/**
* 在线用户列表
* @author zhq
*
*/
public class Online implements ServletContextListener,
HttpSessionListener, HttpSessionAttributeListener {
//声明一个servletContext对象
ServletContext application=null;
//用户若登陆后，又输入用户登陆，则下面的变量派上用场了
String lastUserName;
public String getLastUserName() {
return lastUserName;
}
public void setLastUserName(String lastUserName) {
this.lastUserName = lastUserName;
}
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("*****容摧毁");
}
public void contextInitialized(ServletContextEvent arg0) {
application = arg0.getServletContext();
application.setAttribute("userList", new ArrayList());
System.out.println("*****初始化容器，向application对象中加入一个list对象");
}
public void attributeAdded(HttpSessionBindingEvent arg0) {
List userList=(List)application.getAttribute("userList");
//String userName=(String)arg0.getValue();
String userName=(String)arg0.getSession().getAttribute("userName");
userList.add(userName);
application.setAttribute("userList", userList);
System.out.println("*****用户成功登陆-->"+userName);
this.setLastUserName(userName);
}
public void attributeRemoved(HttpSessionBindingEvent arg0) {
}
public void attributeReplaced(HttpSessionBindingEvent arg0) {
String userName=(String)arg0.getSession().getAttribute("userName");
List userList=(List)application.getAttribute("userList");
userList.remove(this.getLastUserName());
userList.add(userName);
application.setAttribute("userList", userList);
System.out.println("*****用户重写用户名了，"+getLastUserName()+"改为了-->"+userName);
this.setLastUserName(userName);
}
public void sessionCreated(HttpSessionEvent se) {
System.out.println("*****建立新的session连接，ID="+se.getSession().getId());
}
public void sessionDestroyed(HttpSessionEvent se) {
String userName=(String)se.getSession().getAttribute("userName");
List userList=(List)application.getAttribute("userList");
userList.remove(userName);
application.setAttribute("userList", userList);
System.out.println("*****用户退出，用户名"+userName);
}
}
servlet
package com.greendog.servlet;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class Login extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String zhang=request.getParameter("zhang");
if("login".equals(zhang)){
this.login(request, response);
}else if("logout".equals(zhang)){
this.logout(request, response);
}
}
public void login(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String userName=request.getParameter("userName");
HttpSession session=request.getSession();
session.setAttribute("userName", userName);
ServletContext application=getServletContext();
List userList=(List)application.getAttribute("userList");
request.setAttribute("userList", userList);
request.getRequestDispatcher("login.jsp").forward(request, response);
}
public void logout(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session=request.getSession();
session.invalidate();
ServletContext application=getServletContext();
List userList=(List)application.getAttribute("userList");
request.setAttribute("userList", userList);
request.getRequestDispatcher("login.jsp").forward(request, response);
}
}
监听器在web.xml中的配置
<listener>
<listener-class>com.greendog.jiantingqi.Online</listener-class>
</listener> |
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发表于 2011-10-13 17:25:34