JavaWeb-网站在线用户信息、网站访问量以及管理踢出用户实例

这个稍微比上个版本做得完善了一点，用了JavaBean来封装用户信息，添加了一个管理踢用户的功能。
上一个的用户访问量是通过监听request来统计的，在这个实例中，我们也可以通过过滤器来实现统计网站访问量。

直接看源码吧，感觉没多少要讲的，我习惯把解释写在代码中。

部分源码
index.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>在线人信息管理与统计</title>
</head><body><h2>在线人信息管理与统计</h2><c:if test="${empty sessionScope.user}" var="boo"><h3>会员登录:</h3><form action='<c:url value='/LoginServlet'></c:url>' method="post">姓名:<input type='text' name="name"><br /> <input type="submit"value="注册"></form></c:if><c:if test="${!boo}">亲爱的${user.name}<c:if test="${user.admin}" var="bo">-管理员</c:if><c:if test="${!bo}">-会员</c:if>,欢迎来到...<br /></c:if><br /><a href="<c:url value='/servlet/ShowServlet'/>">显示所有在线用户</a><br /><a href="<c:url value='/servlet/LogOutServlet'/>">安全退出</a><br/>网站访问量:${count}</body>
</html>

MyServletContextListener
这个就是实现把访问量持久化的监听器实现类：

package cn.hncu.listeners;import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;public class MyServletContextListener implements ServletContextListener{@Overridepublic void contextInitialized(ServletContextEvent sce) {//从服务器硬盘把之前存储的点击量数据读取出来ServletContext sct = sce.getServletContext();String path = sct.getRealPath("/count.txt");try {BufferedReader br = new BufferedReader(new FileReader(path));String line = br.readLine();Integer count = Integer.valueOf(line);sct.setAttribute("count", count);} catch (Exception e) {//如果出异常了，我们认为文件还不存在，服务器第一次启动e.printStackTrace();sct.setAttribute("count",new Integer(0));}}//关闭服务器时@Overridepublic void contextDestroyed(ServletContextEvent sce) {//把当前servletContext容器中存储的点击量数据 永久化到  服务器硬盘ServletContext sct = sce.getServletContext();String path = sct.getRealPath("/count.txt");try {PrintWriter pw = new PrintWriter(path);pw.write(""+sct.getAttribute("count"));pw.close();} catch (FileNotFoundException e) {e.printStackTrace();}}}

CharsetFilter
实现统计访问量和全站编码的过滤器

package cn.hncu.filter;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;public class CharsetFilter implements Filter{@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {request.setCharacterEncoding("utf-8");response.setContentType("text/html;charset=utf-8");response.setCharacterEncoding("utf-8");//获取该用户的ip,存储到它的session对象中HttpServletRequest req = (HttpServletRequest) request;if(req.getSession().getAttribute("ip")==null){req.getSession().setAttribute("ip", req.getRemoteAddr());//这里的req和request是同一个对象！！！//所以传过去的参数还可以是request}//new一个线程统计访问量new MyThread(request.getServletContext()).start();//放行chain.doFilter(request, response);}@Overridepublic void destroy() {}
}class MyThread extends Thread{private ServletContext servletContext =null;private static Object boj = new Object();public MyThread(ServletContext servletContext) {this.servletContext = servletContext;}@Overridepublic void run() {synchronized (boj) {servletContext.setAttribute("count",(Integer)servletContext.getAttribute("count")+1);}}}

LoginFilter
用户访问其他页面时进行的权限过滤:

如果你没有登陆，就不给你权限去访问除主页外的其他页面。

package cn.hncu.filter;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class LoginFilter implements Filter{@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) request;if(req.getSession().getAttribute("user")==null){HttpServletResponse resp = (HttpServletResponse) response;resp.sendRedirect(req.getContextPath()+"/index.jsp");}else{//放行chain.doFilter(request, response);}}@Overridepublic void destroy() {}}

MySessionListener
有用户来访问时，我们就通过监听器去监听session的创建与销毁，在这里，我们认为一个session就是一个用户！

package cn.hncu.listeners;import java.util.Collections;
import java.util.HashMap;
import java.util.Map;import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;public class MySessionListener implements HttpSessionListener{@Overridepublic void sessionCreated(HttpSessionEvent se) {Map<String, HttpSession> onLines = (Map<String, HttpSession>) se.getSession().getServletContext().getAttribute("onLines");if(onLines==null){//第一个来访问的onLines = Collections.synchronizedMap(new HashMap<String, HttpSession>() );//使用同步技术的Mapse.getSession().getServletContext().setAttribute("onLines", onLines);}onLines.put(se.getSession().getId(), se.getSession());}@Overridepublic void sessionDestroyed(HttpSessionEvent se) {Map<String, HttpSession> onLines = (Map<String, HttpSession>) se.getSession().getServletContext().getAttribute("onLines");//这里也要防范好！多线程，多个管理同时踢一个人的时候，如果不防范就会出问题if(onLines.containsKey( se.getSession().getId() )){onLines.remove( se.getSession().getId() );}}}

LoginServlet
用于判断用户登录与设置管理员的servlet。

package cn.hncu.servlet;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import cn.hncu.domain.User;public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String name = request.getParameter("name");if(name!=null && name.trim().length()>0){User user = new User();user.setName(name);//用user作为参数到后台登录，这里我们简化了，直接假设登录成功if(true){Random r = new Random();int a = r.nextInt(2);if(a%2==0){user.setAdmin(true);}else{user.setAdmin(false);}}request.getSession().setAttribute("user", user);}response.sendRedirect(request.getContextPath()+"/index.jsp");}}

LogOutServlet
用于用户的安全退出！

package cn.hncu.servlet;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class LogOutServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//用户安全退出很简单，我们在服务器端移除用户的session就可以了request.getSession().invalidate();response.sendRedirect(request.getContextPath()+"/index.jsp");}
}

ShowServlet
显示所有用户信息时的servlet，需要把信息全部封装到request这个容器中，再转发到前台jsp显示的页面。

package cn.hncu.servlet;import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class ShowServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {Map<String, HttpSession> onLines = (Map<String, HttpSession>) getServletContext().getAttribute("onLines"); List<Map<String, Object>> lists = new ArrayList<Map<String,Object>>();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//遍历onlines，针对每个session对象封装一个map(信息包含:name,createTime,lastAccessTime,ip)，把该map添加到list当中Iterator<Entry<String, HttpSession>> it = onLines.entrySet().iterator();while(it.hasNext()){Entry<String, HttpSession> en = it.next();Map<String, Object> m = new HashMap<String, Object>();m.put("id", en.getValue().getId() );m.put("user", en.getValue().getAttribute("user"));String creationTime = sdf.format(new Date(en.getValue().getCreationTime()));m.put("creationTime", creationTime);String lastAccessTime = sdf.format( new Date(en.getValue().getLastAccessedTime()) );m.put("lastAccessTime", lastAccessTime);//注意,该ip数据是在CharsetFilter中封装的m.put("ip", en.getValue().getAttribute("ip"));lists.add(m);}request.setAttribute("onLines", lists);request.getRequestDispatcher("/jsps/show.jsp").forward(request, response);}
}

show.jsp
前台在线用户的显示页面，会员和管理员看到的页面是不同的，管理员可以踢人。

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>在线人信息管理</title><style type="text/css">table{border: 1px solid red;border-collapse: collapse;/*设置单线-线合并*/width: 80%;}td{border: 1px solid red;padding:3px;}.header{background: gray;}</style></head><body><h2>以下是所有在线用户信息</h2>   <table><tr class="header" ><td>姓名</td>  <td>上线时间</td>  <td>最后访问时间</td> <td>IP</td> <td>操作</td></tr><c:forEach items="${requestScope.onLines}" var="map"><tr><td><c:if test="${empty map.user}" var="boo">游客                  </c:if><c:if test="${!boo}">${map.user.name}</c:if></td><td>${map.creationTime}  </td><td>${map.lastAccessTime}</td><td>${map.ip }           </td><td><c:if test="${!boo&&user.admin}"><a href="<c:url value='/servlet/KickOutServlet?id=${map.id}'/> " >踢出${map.user.name}</a></c:if></td></tr></c:forEach></table><br/>网站访问量:${count}</body>
</html>

KickOutServlet
管理踢人时请求的servlet，在这里我们把被踢的人的session从服务器端移除就可以了。但是注意防范一下，那个被踢者是否已经被踢走了、

package cn.hncu.servlet;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class KickOutServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();String id = request.getParameter("id");Map<String, HttpSession> onLines = (Map<String, HttpSession>) getServletContext().getAttribute("onLines");if(onLines.containsKey(id)){HttpSession session = onLines.get(id);//得到该sessionsession.invalidate();//移除该sessionout.println("该用户已被踢出!");}else{out.println("该用户已经不存在!");}}
}

user
JavaBean,在这里，我就是简单的封装了一个JavaBean使用了。我们的知识点并不是这里。

package cn.hncu.servlet;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class KickOutServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();String id = request.getParameter("id");Map<String, HttpSession> onLines = (Map<String, HttpSession>) getServletContext().getAttribute("onLines");if(onLines.containsKey(id)){HttpSession session = onLines.get(id);//得到该sessionsession.invalidate();//移除该sessionout.println("该用户已被踢出!");}else{out.println("该用户已经不存在!");}}
}

web.xml
注意啊！无论是servlet还是监听器，过滤器！一定要记得配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"><display-name></display-name> <listener><listener-class>cn.hncu.listeners.MyServletContextListener</listener-class></listener><listener><listener-class>cn.hncu.listeners.MySessionListener</listener-class></listener><servlet><servlet-name>LoginServlet</servlet-name><servlet-class>cn.hncu.servlet.LoginServlet</servlet-class></servlet><servlet><servlet-name>LogOutServlet</servlet-name><servlet-class>cn.hncu.servlet.LogOutServlet</servlet-class></servlet><servlet><servlet-name>ShowServlet</servlet-name><servlet-class>cn.hncu.servlet.ShowServlet</servlet-class></servlet><servlet><servlet-name>KickOutServlet</servlet-name><servlet-class>cn.hncu.servlet.KickOutServlet</servlet-class></servlet><servlet-mapping><servlet-name>LoginServlet</servlet-name><url-pattern>/LoginServlet</url-pattern></servlet-mapping><servlet-mapping><servlet-name>LogOutServlet</servlet-name><url-pattern>/servlet/LogOutServlet</url-pattern></servlet-mapping><servlet-mapping><servlet-name>ShowServlet</servlet-name><url-pattern>/servlet/ShowServlet</url-pattern></servlet-mapping><servlet-mapping><servlet-name>KickOutServlet</servlet-name><url-pattern>/servlet/KickOutServlet</url-pattern></servlet-mapping><filter><filter-name>charset</filter-name><filter-class>cn.hncu.filter.CharsetFilter</filter-class></filter><filter><filter-name>login</filter-name><filter-class>cn.hncu.filter.LoginFilter</filter-class></filter><filter-mapping><filter-name>login</filter-name><url-pattern>/servlet/*</url-pattern><url-pattern>/jsps/*</url-pattern></filter-mapping><filter-mapping><filter-name>charset</filter-name><url-pattern>/*</url-pattern></filter-mapping><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list>
</web-app>

演示结果：
登录之前显示的主页:
未登录的时候，是无法进入显示所有在线用户的，用过滤器拦截了。
这里写图片描述
登录之后显示的主页:

管理员登录后显示的在线人信息
如果不是管理员登录后，最后的操作时不会显示的。

完整的项目链接：
https://github.com/chenhaoxiang/Java/tree/master/myOnlinesWeb2