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listener单点登录和在线人数

1，jsp提交一个form

2，把收集到的数据放到一个personInfo类中，personInfo类放进session中

3，添加的时候触发listener,把一个personInfo的account为key ，session为value,放进一个map中,如果在map找到了这个session,

　　　　证明他已经登陆了，把他弄下线。map重新添加

计算在线人数用一个装满常量的类

1，map的size()就是在线的人数

登陆页面jsp

<%@page contentType="text/html"%>
<%@page pageEncoding="UTF-8"%>
<%@ page import="listen.PersonInfo"%>
<%
    String action = request.getParameter("action");
    String account = request.getParameter("account");

    if ("login".equals(action) && account.trim().length() > 0) {
        PersonInfo personInfo = new PersonInfo();
        personInfo.setAccount(account);
        personInfo.setIp(request.getRemoteAddr());
        personInfo.setLoginDate(new java.util.Date());
        session.setAttribute("personInfo", personInfo);
        response.sendRedirect(response.encodeRedirectURL(request
                .getRequestURI()));
        return;
    } else if ("logout".equals(action)) {
        System.out.println("outout");
        session.removeAttribute("personInfo");
        response.sendRedirect(response.encodeRedirectURL(request
                .getRequestURI()));
        return;
    }
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
    <%
        if (session.getAttribute("personInfo") != null) {
    %>
    欢迎你， ${personInfo.account }.
    <br /> 你的登陆ip, ${personInfo.ip }.
    <br /> 登陆时间 , ${personInfo.loginDate }.
    <a href="${contextPage.request.requestURI }?action=logout">退出</a>
    <script>
        setTimeout("location=location;", 5000);
    </script>
    <%
        } else {
    %>
    ${msg }
    <form action="${contextPage.request.requestURI }?action=login"
        method="post">
        账号: <input name="account" /> <input type="submit" value="登陆">
        <from />

        <%
            }
        %>
    
</body>
</html>

View Code

单点登录

package listen;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class LoginSessionListener implements HttpSessionAttributeListener {

    Log log = LogFactory.getLog(this.getClass());
    Map<String, HttpSession> map = new HashMap<String, HttpSession>();

    @Override
    public void attributeAdded(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub
        String name = event.getName();
        if (name.equals("personInfo")) {
            PersonInfo personInfo = (PersonInfo) event.getValue();
            if (map.get(personInfo.getAccount()) != null) {
                HttpSession session = map.get(personInfo.getAccount());
                PersonInfo oldPersonInfo = (PersonInfo) session
                        .getAttribute("personInfo");
                log.info("账号: " + oldPersonInfo.getAccount() + "被迫下线");
                session.removeAttribute("personInfo");
                session.setAttribute("msg", "你的账号被其他机器登陆了");
            }
            map.put(personInfo.getAccount(), event.getSession());
            log.info("账号:" + personInfo.getAccount() + "在" + personInfo.getIp()
                    + "登陆");
        }
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub
        String name = event.getName();
        if ("personInfo".equals(name)) {
            PersonInfo personInfo = (PersonInfo) event.getValue();
            log.info("账号" + personInfo.getAccount() + "注销");
        }
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub

    }

}

View Code

在线人数

package listen;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class MySessionListener implements HttpSessionListener,
        HttpSessionAttributeListener {

    @Override
    public void sessionCreated(HttpSessionEvent se) {
        // TODO Auto-generated method stub
        Count.TOTAL_HISTORY_COUNT++;// 总访问人数加一
        Count.SESSION_MAP.put(se.getSession().getId(), se.getSession());// 放进去
        if (Count.SESSION_MAP.size() > Count.MAX_ONLINE_COUNT) {
            Count.MAX_ONLINE_COUNT = Count.SESSION_MAP.size();
        }
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        // TODO Auto-generated method stub
        HttpSession session = se.getSession();
        Count.SESSION_MAP.remove(session.getId());
    }

    @Override
    public void attributeAdded(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub
        if ("personInfo".equals(event.getName())) {
            Count.CURRENT_LOGIN_COUNT++;// 当前在线人数加一
            HttpSession session = event.getSession();
        }
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub
        if (event.getName().equals("personInfo")) {
            Count.CURRENT_LOGIN_COUNT--;
        }
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent event) {
        // TODO Auto-generated method stub

    }

}

View Code

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原文地址：https://www.cnblogs.com/vhyc/p/6548495.html