JavaEE在线人数管理系统

2019-11-26 13:49:55

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来源：转载

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这篇博客是filter、listener和servlet技术的相关总结，实现了简单的显示在线人数、在线人详细信息、管理员踢人功能

下面是详细代码

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>  <filter> <filter-name>character</filter-name> <filter-class>cn.hncu.filter.CharacterFilter</filter-class> <init-param>  <param-name>charset</param-name>  <param-value>utf-8</param-value> </init-param> </filter> <filter> <filter-name>login</filter-name> <filter-class>cn.hncu.filter.LoginFilter</filter-class> </filter> <filter-mapping> <filter-name>character</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>login</filter-name> <url-pattern>/servlet/*</url-pattern> <url-pattern>/jsps/*</url-pattern> <dispatcher>REQUEST</dispatcher> <dispatcher>FORWARD</dispatcher> </filter-mapping> <listener> <listener-class>cn.hncu.listener.MySessionListener</listener-class> </listener> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.hncu.servlet.LoginServlet</servlet-class> </servlet> <servlet> <servlet-name>ShowServlet</servlet-name> <servlet-class>cn.hncu.servlet.ShowServlet</servlet-class> </servlet> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>KickOutServlet</servlet-name> <servlet-class>cn.hncu.servlet.KickOutServlet</servlet-class> </servlet> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LoginOutServlet</servlet-name> <servlet-class>cn.hncu.servlet.LoginOutServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</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> <servlet-mapping> <servlet-name>LoginOutServlet</servlet-name> <url-pattern>/servlet/LoginOutServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>在线人信息管理</title> </head> <body> <h2>在线人信息管理</h2> <h3>会员登录</h3> <c:if test="${ empty sessionScope.user.name}" var="boo">  <form action='<c:url value="/LoginServlet"></c:url>'>   姓名:<input type="text" name="name"><br/>    <input type="submit" value="登录"><br/>  </form> </c:if> <c:if test="${!boo}" >  欢迎回来,${ sessionScope.user.name}  <c:if test="${ sessionScope.user.admin}" var="bo">   管理员  </c:if>  <c:if test="${!bo}" >   会员  </c:if> </c:if> <br/>  <c:if test="${!boo}" var="boo">  <a href='<c:url value="/servlet/ShowServlet"/>'>查看在线人信息</a><br/>  <a href='<c:url value="/servlet/LoginOutServlet"/>'>安全退出</a><br/>  </c:if> </body></html>

/jsps/show.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</title><style type="text/css"> table {  color: green;  border: 1px solid blue;  border-collapse: collapse;  width: 500px;  margin: auto; } td {  border: 1px solid blue; } th {  border: 1px solid blue; } body {  text-align: center; }</style> <meta http-equiv="refresh" content="3"></head><body> <table>  <tr>   <th>姓名</th>   <th>上线时间</th>   <th>最后访问时间</th>   <th>ip</th>   <th>操作</th>  </tr>  <c:forEach items="${requestScope.onlines}" var="online">  <tr>   <td>    <c:if test="${!empty online.user }" var="boo">      ${online.user.name }    </c:if>    <c:if test="${empty online.user }">      游客    </c:if>   </td>   <td>${online.createTime }</td>   <td>${online.lastAccessedTime }</td>   <td>${online.ip }</td>   <td>    <c:if test="${online.user!=sessionScope.user }">      <c:if test="${!online.user.admin&&boo}">       <a href='<c:url value="/servlet/KickOutServlet?id=${online.id }"/>' >踢出</a>     </c:if>    </c:if>   </td>  </tr>  </c:forEach> </table></body></html>

User.java(值对象）

package cn.hncu.domain;public class User { private String name; private boolean admin; public String getName() {  return name; } public void setName(String name) {  this.name = name; } public boolean isAdmin() {  return admin; } public void setAdmin(boolean admin) {  this.admin = admin; } @Override public String toString() {  return "User [name=" + name + ", admin=" + admin + "]"; }}

MySessionListener.java(监听器）

package cn.hncu.listener;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{ @Override public void sessionCreated(HttpSessionEvent se) {  Map<String, HttpSession> onlines= (Map<String, HttpSession>) se.getSession().getServletContext().getAttribute("onlines");  if(onlines==null){   onlines=Collections.synchronizedMap(new HashMap<String, HttpSession>());//对map进行加上同步锁   se.getSession().getServletContext().setAttribute("onlines",onlines);  }  onlines.put(se.getSession().getId(), se.getSession()); } @Override public void sessionDestroyed(HttpSessionEvent se) {  Map<String, HttpSession> onlines= (Map<String, HttpSession>) se.getSession().getServletContext().getAttribute("onlines");  if(onlines.containsKey(se.getSession().getId())){   onlines.remove(se.getSession().getId());  } }}

CharacterFilter.java(字符过滤器）

package cn.hncu.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;public class CharacterFilter implements Filter { private String charset; @Override public void init(FilterConfig filterConfig) throws ServletException {  charset=filterConfig.getInitParameter("charset"); } @Override public void doFilter(ServletRequest request, ServletResponse response,   FilterChain chain) throws IOException, ServletException {  request.setCharacterEncoding(charset);  response.setCharacterEncoding(charset);  HttpServletRequest req=(HttpServletRequest) request;  if(req.getSession().getAttribute("ip")==null){   req.getSession().setAttribute("ip", req.getRemoteAddr());  }  chain.doFilter(request, response); } @Override public void destroy() { }}

LoginFilter.java(防止游客乱访问过滤器）

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

LoginServlet.java

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;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");  User user=(User) request.getSession().getAttribute("user");  if (user==null&&name!=null&&name.trim().length()>0) {//封装User   user = new User();   user.setName(name);   if(name.equals("admin")){    user.setAdmin(true);   }  }  request.getSession().setAttribute("user", user);  response.sendRedirect(request.getContextPath()+"/index.jsp"); }}

ShowServlet.java

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 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>) request.getServletContext().getAttribute("onlines");  List<Map<String, Object>> list=new ArrayList<Map<String,Object>>();//吧Online封装成list  if (onlines!=null) {   Iterator<HttpSession> it = onlines.values().iterator();   while (it.hasNext()) {    HttpSession s = it.next();    Map<String, Object> map = new HashMap<String, Object>();    map.put("id", s.getId());    SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");    map.put("createTime", sdf.format(new Date(s.getCreationTime())));    map.put("lastAccessedTime",sdf.format(new Date(s.getLastAccessedTime())) );    map.put("ip", s.getAttribute("ip"));//ip信息在characterFilter中补    map.put("user", s.getAttribute("user"));    list.add(map);   }  }  request.setAttribute("onlines", list);  request.getRequestDispatcher("/jsps/show.jsp").forward(request, response); }}

KickOutServlet.java

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 {  String id=request.getParameter("id");  Map<String, HttpSession> onlines=(Map<String, HttpSession>) request.getServletContext().getAttribute("onlines");  if (onlines!=null) {   if (onlines.containsKey(id)) {    onlines.get(id).invalidate();   }  }  request.getRequestDispatcher("/servlet/ShowServlet").forward(request, response); }}

LoginOutServlet.java

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 LoginOutServlet 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 {   request.getSession().invalidate();   response.sendRedirect(request.getContextPath()+"/index.jsp"); }}

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