监听器模拟用户在线
由于会话管理机制的原因，用户需在不同的浏览器上进行登录。 期间可以访问onlineservlet查询在线用户列表。
设置监听器：
1 package com.listener;
2
3 import java.util.LinkedList;
4 import java.util.List;
5
6 import javax.faces.application.Application;
7 import javax.servlet.ServletContext;
8 import javax.servlet.ServletContextEvent;
9 import javax.servlet.ServletContextListener;
10 import javax.servlet.annotation.WebListener;
11 import javax.servlet.http.HttpSessionAttributeListener;
12 import javax.servlet.http.HttpSessionBindingEvent;
13 import javax.servlet.http.HttpSessionEvent;
14 import javax.servlet.http.HttpSessionListener;
15 @WebListener
16 public class OnlineListener implements HttpSessionListener,
17 HttpSessionAttributeListener, ServletContextListener {
18 private ServletContext application;
19 @Override
20 public void contextInitialized(ServletContextEvent arg0) {
21 //上下文启动时创建list放进application用来存放在线用户列表
22 List<String> list = new LinkedList<>();
23 application = arg0.getServletContext();
24 application.setAttribute("online",list);
25 }
26
27 @Override
28 public void attributeAdded(HttpSessionBindingEvent arg0) {
29 //session属性添加时调用 将登陆的用户名存进list
30 String name = (String) arg0.getSession().getAttribute("name");
31 List<String> list =(List<String>)application.getAttribute("online");
32 list.add(name);
33 application.setAttribute("online",list);
34 }
35 @Override
36 public void sessionDestroyed(HttpSessionEvent arg0) {
37 //session 结束时调用 将下线的用户从list中去除
38 System.out.println("session destroyed");
39 List<String> list = (List<String>)application.getAttribute("online");
40 String name =(String) arg0.getSession().getAttribute("name");
41 list.remove(name);
42 application.setAttribute("online",list);
43 }
44 @Override
45 public void sessionCreated(HttpSessionEvent arg0)
46 {}
47 @Override
48 public void attributeRemoved(HttpSessionBindingEvent arg0) {}
49 @Override
50 public void attributeReplaced(HttpSessionBindingEvent arg0) {}
51 @Override
52 public void contextDestroyed(ServletContextEvent arg0) {}
53 }
登录serlet：
1 package com.servlet;
2
3 import java.io.IOException;
4
5 import javax.jms.Session;
6 import javax.servlet.ServletException;
7 import javax.servlet.annotation.WebServlet;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 import javax.servlet.http.HttpSession;
12 @WebServlet(name="loginservlet",urlPatterns="/loginservlet")
13 /**
14 * 用户的登陆
15 * @author Administrator
16 *
17 */
18 public class LoginServlet extends HttpServlet {
19
20 @Override
21 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
22 throws ServletException, IOException {
23 doPost(req, resp);
24 }
25
26 @Override
27 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
28 throws ServletException, IOException {
29 String name = req.getParameter("name");
30 HttpSession session = req.getSession();
31 if(null!=name){
32 session.setAttribute("name",name);
33 resp.sendRedirect("main.jsp");
34 }
35 }
36
37
38 }
下线servlet：
1 package com.servlet;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5 import java.util.List;
6
7 import javax.faces.application.Application;
8 import javax.servlet.ServletException;
9 import javax.servlet.annotation.WebServlet;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13 @WebServlet(name="logoutservlet",urlPatterns="/logoutservlet")
14 /**
15 * 用户的下线
16 * @author Administrator
17 *
18 */
19 public class LogoutServlet extends HttpServlet {
20
21 @Override
22 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
23 throws ServletException, IOException {
24 doPost(req, resp);
25 }
26
27 @Override
28 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
29 throws ServletException, IOException {
30 req.setCharacterEncoding("utf8");
31 resp.setCharacterEncoding("utf8");
32 resp.setContentType("text/html;charset=UTF-8");
33 req.getSession().invalidate();//会话销毁
34 PrintWriter out = resp.getWriter();
35
36 out.println("在线用户:");
37 List<String> list = (List)getServletContext().getAttribute("online");
38 for (String s : list) {
39 out.println(s);
40 }
41 }
42
43 }
在线用户查询servlet：
1 package com.servlet;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5 import java.util.List;
6
7 import javax.servlet.ServletException;
8 import javax.servlet.annotation.WebServlet;
9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 @WebServlet(name="onlineservlet",urlPatterns="/onlineservlet")
13 /**
14 * 通过访问可以查询在线用户名单
15 * @author Administrator
16 *
17 */
18 public class OnlineServlet extends HttpServlet {
19
20 @Override
21 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
22 throws ServletException, IOException {
23 doPost(req, resp);
24 }
25
26 @Override
27 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
28 throws ServletException, IOException {
29 resp.setContentType("text/html;charset=UTF-8");
30 PrintWriter out = resp.getWriter();
31 out.println("在线用户:");
32 List<String> list = (List)getServletContext().getAttribute("online");
33 for (String s : list) {
34 out.println(s);
35 }
36 }
37
38 }
登录界面jsp：
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
2 <%
3 String path = request.getContextPath();
4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
5 %>
6
7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
8 <html>
9 <head>
10 <base href="<%=basePath%>">
11
12 <title>My JSP 'index.jsp' starting page</title>
13 <meta http-equiv="pragma" content="no-cache">
14 <meta http-equiv="cache-control" content="no-cache">
15 <meta http-equiv="expires" content="0">
16 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17 <meta http-equiv="description" content="This is my page">
18 <!--
19 <link rel="stylesheet" type="text/css" href="styles.css">
20 -->
21 </head>
22
23 <body>
24 <form action="loginservlet" method="postggi">
25 <center>
26 name:<input type="text" name="name"><br>
27 <input type="submit" value="load..">
28 </center>
29 </form>
30 </body>
31 </html>
登录后主界面：
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
2 <%
3 String path = request.getContextPath();
4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
5 %>
6
7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
8 <html>
9 <head>
10 <base href="<%=basePath%>">
11
12 <title>main</title>
13
14 <meta http-equiv="pragma" content="no-cache">
15 <meta http-equiv="cache-control" content="no-cache">
16 <meta http-equiv="expires" content="0">
17 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
18 <meta http-equiv="description" content="This is my page">
19 <!--
20 <link rel="stylesheet" type="text/css" href="styles.css">
21 -->
22
23 </head>
24
25 <body>
26 <center>
27 <form action="logoutservlet" method="post">
28 <%
29 String name = (String)session.getAttribute("name");
30 %>
31 <%=name %>欢迎登录
32 <br><input type="submit" value="注销">
33 </form>
34 </center>
35 </body>
36 </html>
