Servlet监听器的简单使用实现统计在线人数

原创已于 2022-04-18 16:47:34 修改 · 1.7k 阅读

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于 2017-02-27 16:14:36 首次发布

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下面用一个示例演示HttpSessionBindingListener监听器的使用：

package com.home.web.manager;

import java.util.Vector;

/**
 * 
 * @description 用户管理
 * @author fj
 * @createTime 2017年2月27日
 */
public class UserInfoList {

    private static UserInfoList user = new UserInfoList();

    private Vector<String> vector = null;

    public UserInfoList() {
        this.vector = new Vector<>();
    }

    public static UserInfoList getInstance() {
        return user;
    }

    public boolean addUserInfo(String user) {
        if (user != null) {
            vector.addElement(user);
            return true;
        } else {
            return false;
        }

    }

    public Vector<String> getList() {
        return vector;
    }

    public void removeUserInfo(String user) {
        if (user != null) {
            vector.removeElement(user);
        }
    }

}

package com.home.web.manager;

import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;

/**
 * 
 * @description 用来监听用户在线状态
 * @author fj
 * @createTime 2017年2月27日
 */
public class UserInfoTrace implements HttpSessionBindingListener {

    private String user;

    private UserInfoList container = new UserInfoList();

    public UserInfoTrace() {
        user = "";
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }

    public UserInfoList getContainer() {
        return container;
    }

    public void setContainer(UserInfoList container) {
        this.container = container;
    }

    @Override
    public void valueBound(HttpSessionBindingEvent arg0) {
        System.out.println(user + "上线了");
    }

    @Override
    public void valueUnbound(HttpSessionBindingEvent arg0) {
        System.out.println(user + "下线了");
        if (user != "") {
            container.removeUserInfo(user);
        }
    }

}

index.jsp：

<%@page import="java.net.URLDecoder"%>
<%@ 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>登录页</title>
</head>
<body>

	<form action="result.jsp" method="post">
		<table align="center"  width="350">
			<tr>
				<td class="2" align="center" colspan="2">
					<h2>在线登录系统</h2>
				</td>
			</tr>
			<tr>
				<td align="center" colspan="2"><input type="text"  name="user"></td>
			</tr>
			<tr>
				<td class="2" align="center" colspan="2"><input type="submit"
					value="登录"></td>
			</tr>
		</table>
	</form>

</body>
</html>

result.jsp：

<%@page import="com.home.web.manager.UserInfoTrace"%>
<%@page import="com.home.web.manager.UserInfoList"%>
<%@ page language="java" import="java.util.*" autoFlush="true"
	import="com.home.web.mamager.*" 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>

	<%
	    String name = request.getParameter("user");
	    UserInfoList list = UserInfoList.getInstance();
	    UserInfoTrace ut = new UserInfoTrace();
	    ut.setUser(name);
	    session.setAttribute("list", ut);
	    list.addUserInfo(ut.getUser());
	    session.setMaxInactiveInterval(1);
	%>

	<textarea rows="8" cols="20">
<%
    Vector vector = list.getList();
    if (vector != null && vector.size() > 0) {
        for (int i = 0; i < vector.size(); i++) {
            out.println(vector.elementAt(i));
        }
    }
%>
</textarea>


</body>
</html>