SessionCounter.java
==============
package SessionCount;
import javax.servlet.*;
import javax.servlet.http.*;
public class SessionCounter implements HttpSessionListener {
private static int activeSessions = 0;
public void sessionCreated(HttpSessionEvent se) {
activeSessions++;
}
public void sessionDestroyed(HttpSessionEvent se) {
if(activeSessions > 0)
activeSessions--;
}
public static int getActiveSessions() {
return activeSessions;
}
}
web.xml
=========
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="
http://java.sun.com/xml/ns/j2ee
"
xmlns:xsi="
http://www.w3.org/2001/XMLSchema-instance
"
xsi:schemaLocation="
http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd
">
...............
<!-- Listeners -->
<listener>
<listener-class>
SessionCount.SessionCounter
</listener-class>
...............
</listener>
</web-app>
===============
test.jsp
<%@ page language="Java" contentType="text/html;charset=GBK"%>
<%@ page import="java.sql.*"%>
<%@ page import="SessionCount.SessionCounter" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>无标题文档</title>
<body bgcolor="#FFFFFF">
在线:<%=SessionCounter.getActiveSessions()%>
</body>
</html>
