/CHATROOM/WebContent/doLogin.jsp：
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
// 设置编码格式
request.setCharacterEncoding("UTF-8");
// 获取登录的用户名
String userName = request.getParameter("account");
// 从application对象中把存储的用户列表获取到
List<String> userList = (List<String>) application.getAttribute("userList");
// 判断你否为第一个登录该系统
if(userList==null) {
// 创建存储在线用户列表对象集合
userList = new ArrayList<String>();
}
// 判断当前登录用户名是否已存在
if(userList.contains(userName)) {
out.print("<script>alert(‘该用户已经登录,使用其他用户名登录‘);location.href=‘login.jsp‘;</script>");
return;
}
// 把当前登录的用户存储在在线用户列表集合中
userList.add(userName);
// 把在线用户列表存储在application对象中
application.setAttribute("userList", userList);
// 把当前登录用户存储到session对象中
session.setAttribute("currentUser", userName);
// 跳转到聊天主页
response.sendRedirect("index.jsp");
%>/CHATROOM/WebContent/doSend.jsp：
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
// 设置编码
request.setCharacterEncoding("UTF-8");
// 获取用户发送消息
String message = request.getParameter("message");
// 获取发送用户名称
String userName = (String)session.getAttribute("currentUser");
// 组合消息文本
String content = "<font color=‘blue‘>"+userName+"说:</font><br/> "+message+"<br/><br/>";
// 获取存储在application当中已经发送过消息集合
List<String> messages = (List<String>)application.getAttribute("msglist");
// 判断是否为第一发送信息的用户
if(messages == null) {
messages = new ArrayList<String>();
}
// 在把当前用户发送的信息存储到消息列表集合中
messages.add(content);
// 在把新的信息列表存储到application中
application.setAttribute("msglist", messages);
// 跳转到index.jsp页面
response.sendRedirect("sendMessage.jsp");
%>/CHATROOM/WebContent/index.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!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> <link href="css/main.css" type="text/css" rel="stylesheet" /> </head> <body> <center> <table width="50%" border="1px" cellpadding="0" cellspacing="0"> <caption>YC59公共聊天室</caption> <tr> <td rowspan="2" height="500px" width="26%"> <iframe src="userlist.jsp" align="top" width="100%" height="100%" frameborder="0" scrolling="auto"></iframe> </td> <td height="360px"> <iframe align="top" src="showMessageList.jsp" width="100%" height="100%" frameborder="0" scrolling="auto"></iframe> </td> </tr> <tr> <td> <iframe src="sendMessage.jsp" align="top" width="100%" height="100%" frameborder="0" scrolling="auto"></iframe> </td> </tr> </table> </center> </body> </html>
/CHATROOM/WebContent/login.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!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> <link href="css/main.css" type="text/css" rel="stylesheet" /> </head> <body> <fieldset> <legend>英才59班聊天室登录</legend> <form action="doLogin.jsp" method="post"> <table> <tr> <th>用户名:</th> <td><input type="text" name="account" /></td> </tr> <tr> <th>密码:</th> <td><input type="password" name="pass" /></td> </tr> <tr> <td colspan="2"> <input type="submit" value=" 登 录 " /> </td> </tr> </table> </form> </fieldset> </body> </html>
/CHATROOM/WebContent/sendMessage.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!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> <form action="doSend.jsp" method="post"> <textarea rows="6" cols="60" name="message"></textarea> <br/> <span> <input type="submit" value=" 发 送 " /> </span> </form> </body> </html>
/CHATROOM/WebContent/showMessageList.jsp：
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<meta http-equiv="refresh" content="1">
<%
// 获取存储在application当中已经发送过消息集合
List<String> messages = (List<String>)application.getAttribute("msglist");
if(messages != null && messages.size()>0) {
for(String message : messages) {
out.print(message);
}
}
%>原文：http://lhmjava.blog.51cto.com/9668287/1623338