JSP&Servlet 统计在线人数及信息

来源：互联网发布：php 笛卡尔乘积算法编辑：程序博客网时间：2024/05/05 23:49

首先创建一个javabean的user类：
包括sessionIdString，ipString，firstTimeString属性。
创建session监听：

    @WebListener    public class MyHttpSessionListener implements HttpSessionListener {        private int userNumber = 0;        @Override        public void sessionCreated(HttpSessionEvent arg0) {            userNumber++;            arg0.getSession().getServletContext().setAttribute("userNumber", userNumber);        }        @Override        public void sessionDestroyed(HttpSessionEvent arg0) {            userNumber--;            arg0.getSession().getServletContext().setAttribute("userNumber", userNumber);            ArrayList<User> userList = null;//在线用户List            userList = (ArrayList<User>) arg0.getSession().getServletContext().getAttribute("userList");            if (SessionUtil.getUserBySessionId(userList, arg0.getSession().getId()) != null) {                userList.remove(SessionUtil.getUserBySessionId(userList, arg0.getSession().getId()));            }        }    }

创建一个请求监听：

    @WebListener    public class MyServletRequestListener implements ServletRequestListener {        private ArrayList<User> userList;//在线用户List        @Override        public void requestDestroyed(ServletRequestEvent arg0) {        }        @Override        public void requestInitialized(ServletRequestEvent arg0) {            userList = (ArrayList<User>) arg0.getServletContext().getAttribute("userList");            if (userList == null)                userList = new ArrayList<User>();            HttpServletRequest request = (HttpServletRequest) arg0.getServletRequest();            String sessionIdString = request.getSession().getId();            if (SessionUtil.getUserBySessionId(userList, sessionIdString) == null) {                User user = new User();                user.setSessionIdString(sessionIdString);                user.setFirstTimeString(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));                user.setIpString(request.getRemoteAddr());                userList.add(user);            }            arg0.getServletContext().setAttribute("userList", userList);        }    }

实现请求监听中的getUserBySessionId方法，创建单独的类SessionUtil实现：

    public class SessionUtil {        public static Object getUserBySessionId(ArrayList<User> userList, String sessionIdString) {            for (int i = 0; i < userList.size(); i++) {                User user = userList.get(i);                if (user.getSessionIdString().equals(sessionIdString)) {                    return user;                }            }            return null;        }    }

修改index.jsp:

<body>    当前在线用户人数:${userNumber }<br/>    <%    ArrayList<com.imooc.entity.User>  userList =  (ArrayList<com.imooc.entity.User>)request.getServletContext().getAttribute("userList");    if(userList!=null){       for(int i = 0 ; i < userList.size() ; i++){      com.imooc.entity.User user = userList.get(i);   %>    IP:<%=user.getIpString() %>,FirstTime:<%=user.getFirstTimeString() %>,SessionId:<%=user.getSessionIdString() %> <br/>    <%}} %>  </body>

打开一个浏览器，进入index.jsp:
网页显示：
当前在线用户人数:1
IP:0:0:0:0:0:0:0:1,FirstTime:2015-09-09 21:32:38,SessionId:707E948E950F1A4AB963275EC5C1055B
打开另一不同的浏览器
显示：
当前在线用户人数:2
IP:0:0:0:0:0:0:0:1,FirstTime:2015-09-09 21:32:38,SessionId:707E948E950F1A4AB963275EC5C1055B
IP:0:0:0:0:0:0:0:1,FirstTime:2015-09-09 21:33:46,SessionId:8B11D420FB1166266745510293E1B05D
刷新第一个，显示第二个相同。

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