image.png
image.png
UserInfo
package com.baozi;
import java.util.Vector;
public class UserInfo {
@SuppressWarnings("rawtypes")
private Vector vec=new Vector();
private static UserInfo user=new UserInfo();
@SuppressWarnings("rawtypes")
public UserInfo(){
vec=new Vector();
}
public static UserInfo getInstance(){
return user;
}
@SuppressWarnings("unchecked")
public boolean addUserInfo(String user){
if(user!=null){
vec.addElement(user);
return true;
}
return false;
}
@SuppressWarnings("rawtypes")
public Vector getUserInfo(){
return vec;
}
public void removeUserInfo(String user){
vec.removeElement(user);
}
}
UserInfoTrace
package com.baozi;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
public class UserInfoTrace implements HttpSessionBindingListener {
private String user;
private UserInfo uinf=UserInfo.getInstance();
public void setUser(String user){
this.user=user;
}
public String getUser(){
return user;
}
public void valueBound(HttpSessionBindingEvent arg0) {
System.out.println("上线"+user);
}
public void valueUnbound(HttpSessionBindingEvent arg0) {
System.out.println("下线"+user);
if(user!="")
uinf.removeUserInfo(user);
}
}
index.jsp
<%@ page language="java" contentType="text/html; charset=gb2312"
pageEncoding="gb2312" isErrorPage="true"%>
<%request.setCharacterEncoding("gb2312"); %>
<%@page import="com.baozi.*" %>
<!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=gb2312">
<title>问卷调查</title>
</head>
<body>
<form action="showUser.jsp" method="post">
用户名<input name="user" type="text"><br>
<input type="Submit" type="submit" value="登录">
</form>
</body>
</html>
showuser.jsp
<%@ page language="java" contentType="text/html; charset=gb2312"
pageEncoding="gb2312"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ page import="java.util.*" %>
<%@ page import="com.baozi.*" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>在线信息</title>
</head>
<%
session.setMaxInactiveInterval(10);
UserInfo list=UserInfo.getInstance();
UserInfoTrace ut=new UserInfoTrace();
String name=request.getParameter("user");
ut.setUser(name);
session.setAttribute("list",ut);
list.addUserInfo(ut.getUser());
%>
<textarea rows="8" cols="20">
<%Vector vec=list.getUserInfo();
if(vec!=null&&vec.size()>0){
for(int i=0;i<vec.size();i++)
out.println(vec.elementAt(i));
}
%>
</textarea>
</body>
</html>
