JavaWeb---在线用户显示与管理---(监听器/过滤器)
2017-02-27 19:32
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管理登录(在线用户):
第一步:书写一个HttpSession的监听,并维护一个LinkedHashMap,其中保存着所有用户的Session.
第二步:让上面的类,同时实现ServletContextListener接口,并将LinkedHashMap添加到ServletContext对像中。
第三步:实现一个页面,显示所有SessionID。
第四步:在页面上添加踢出按扭,通过SessionID在Map中查询指定的Session,然后执行它的invalidate方法,清除它。从而实现踢出用户的功能。
第五步:改进,应该通过HttpSessionAttributeListener监听器,只踢出登录成功的用户。对于游客不用关心,并且只有管理员有权限踢人。
index.jsp
web.xml
show.jsp
过滤器:
CharsetFilter.java
LoginFilter.java
监听器:
MySessionListener.java
值对象:
User.java
Servlet:
LoginServlet.java
ShowServlet.java
LogOutServlet.java
KickOutServlet.java
用户登录界面如下:
登陆成功界面:
显示联系人界面:
第一步:书写一个HttpSession的监听,并维护一个LinkedHashMap,其中保存着所有用户的Session.
第二步:让上面的类,同时实现ServletContextListener接口,并将LinkedHashMap添加到ServletContext对像中。
第三步:实现一个页面,显示所有SessionID。
第四步:在页面上添加踢出按扭,通过SessionID在Map中查询指定的Session,然后执行它的invalidate方法,清除它。从而实现踢出用户的功能。
第五步:改进,应该通过HttpSessionAttributeListener监听器,只踢出登录成功的用户。对于游客不用关心,并且只有管理员有权限踢人。
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</title> </head> <body> <h2>在线人信息管理</h2> <c:if test="${empty sessionScope.user}" var="boo"> <h3>会员登录</h3> <form action="<c:url value='/LoginServlet'/>" method="post"> 姓名:<input type="text" name="name" /><br/> <input type="submit" value="输入任意名即可登录"/> </form> </c:if> <c:if test="${!boo}"> 欢迎你:${user.name } <c:if test="${user.admin}" var="bo"> 管理员 </c:if> <c:if test="${!bo}"> 会员 </c:if> <br/> <a href="<c:url value='/servlet/ShowServlet'/>">显示所有在线用户</a> <br/> <a href="<c:url value='/servlet/LogOutServlet'/>">安全退出</a> </c:if> </body> </html>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <filter> <filter-name>charset</filter-name> <filter-class>cn.hncu.filter.CharsetFilter</filter-class> </filter> <filter> <filter-name>login</filter-name> <filter-class>cn.hncu.filter.LoginFilter</filter-class> </filter> <filter-mapping> <filter-name>charset</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>login</filter-name> <url-pattern>/servlet/*</url-pattern> <url-pattern>/jsps/*</url-pattern> </filter-mapping> <listener> <listener-class>cn.hncu.listener.MySessionListener</listener-class> </listener> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.hncu.servlet.LoginServlet</servlet-class> </servlet>
show.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>在线人信息管理</title> <style type="text/css"> table{ border: 1px solid red; border-collapse: collapse; width: 80%; } td{ border: 1px solid red; padding:3px; } .header{ background: gray; } </style> </head> <body> <h2>以下是所有在线用户信息</h2> <table> <tr class="header" > <td>姓名</td> <td>上线时间</td> <td>最后访问时间</td> <td>IP</td> <td>操作</td> </tr> <c:forEach items="${requestScope.onLines}" var="m" > <tr> <td> <c:if test="${empty m.user}" var="boo"> 游客 </c:if> <c:if test="${ !boo }"> ${ m.user.name } </c:if> </td> <td> ${m.creationTime} </td> <td> ${m.lastAccessTime }</td> <td> ${m.ip } </td> <td> <c:if test="${!boo && m.user.admin }"> <a href="<c:url value='/servlet/KickOutServlet?id=${m.id}'/> " >踢出</a> </c:if> </td> </tr> </c:forEach> </table> </body> </html>
过滤器:
CharsetFilter.java
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 CharsetFilter implements Filter{ @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=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() ); } chain.doFilter(request, response);//放行 } @Override public void destroy() { } }
LoginFilter.java
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 resp = (HttpServletResponse) response; resp.sendRedirect(req.getContextPath()+"/index.jsp"); }else{ chain.doFilter(request, response); } } @Override public void destroy() { } }
监听器:
MySessionListener.java
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){//沙发 onLines = Collections.synchronizedMap( new HashMap<String, HttpSession>() ); //使用同步技术的Map 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() ); } } }
值对象:
User.java
package cn.hncu.domain; public class User { private String name; private String pwd; private boolean admin; public User() { super(); } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } public boolean isAdmin() { return admin; } public void setAdmin(boolean admin) { this.admin = admin; } }
Servlet:
LoginServlet.java
package cn.hncu.servlet; import java.io.IOException; 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"); 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 Random r = new Random(); int a = r.nextInt(10); if(a%2==0){ user.setAdmin(true); }else{ user.setAdmin(false); } request.getSession().setAttribute("user", user); response.sendRedirect(request.getContextPath()+"/index.jsp"); } }
ShowServlet.java
package cn.hncu.servlet; import java.io.IOException; 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>> list = 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); m.put("ip", en.getValue().getAttribute("ip") ); //注意,该ip数据是在CharsetFilter中封装的 list.add(m); } request.setAttribute("onLines",list); request.getRequestDispatcher("/jsps/show.jsp").forward(request, response); } }
LogOutServlet.java
package cn.hncu.servlet; import java.io.IOException; 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 { request.getSession().invalidate(); response.sendRedirect(request.getContextPath()+"/index.jsp"); } }
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 { 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); session.invalidate(); out.println("该用户已被踢出!"); }else{ out.println("该用户已经不存在!"); } } }
用户登录界面如下:
登陆成功界面:
显示联系人界面:
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