使用listener,实现在线用户列表时，显示第一次输入的用户，，(代码多，但是一粘贴，复制，既没)
代码虽多，一目了然
先是实体User
package entity;
public class User {
private String username;
private String password;
public User(String username, String password) {
super();
this.username = username;
this.password = password;
}
public User() {
super();
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
-----------------------------------------------------------------------------------------
OnLineUserListener监听器内容
package listener;
import java.util.HashSet;
import java.util.Set;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import entity.User;
public class OnLineUserListener implements ServletContextListener,
HttpSessionAttributeListener, HttpSessionListener {
private ServletContext application;
public void sessionCreated(HttpSessionEvent arg0) {
}
public void sessionDestroyed(HttpSessionEvent arg0) {
HttpSession session=arg0.getSession();
User logoutUser=(User) session.getAttribute("user");
Set<User> logOutUser=(Set)application.getAttribute("onLineUsers");
}
public void attributeAdded(HttpSessionBindingEvent arg0) {
HttpSession session=arg0.getSession();
User newuser=(User)session.getAttribute("user");
Set<User> onLineUsers=(Set)application.getAttribute("onLineUsers");
onLineUsers.add(newuser);
}
public void attributeRemoved(HttpSessionBindingEvent arg0) {
User logOutUser=(User)arg0.getValue();
Set<User> onLineUsers=(Set)application.getAttribute("onLineUsers");
onLineUsers.remove(logOutUser);
}
public void attributeReplaced(HttpSessionBindingEvent arg0) {
// TODO Auto-generated method stub
}
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}
public void contextInitialized(ServletContextEvent arg0) {
Set<User> onLineUsers=new HashSet<User>();// 创建一个用于存放onLineUsers对象的set集合对象
application=arg0.getServletContext();
application.setAttribute("onLineUsers", onLineUsers);
}
}
-----------------------------------------------
login.jsp内容
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="LoginServlet" method="post">
账户：<input type="text" name="username"/><br/>
密码：<input type="password" name="userpwd"/><br/>
<input type="submit" value="登陆"/>
</form>
</body>
</html>
-----------------------------------------------------
servler
package 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 javax.servlet.http.HttpSession;
import entity.User;
public class LoginServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public LoginServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String username=request.getParameter("username");//userpwd
String userpwd=request.getParameter("userpwd");
request.getSession().setAttribute("user",new User(username,userpwd));
System.out.println("username"+username);
request.getRequestDispatcher("show.jsp").forward(request, response);
out.flush();
out.close();
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
----------------------------------------------web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 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_2_5.xsd">
<listener>
<listener-class>listener.OnLineUserListener</listener-class>
</listener>
<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>LoginServlet</servlet-name>
<servlet-class>servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<login-config>
<auth-method>BASIC</auth-method>
</login-config>
</web-app>
-------------------------------------------show.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core_rt"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<c:forEach items="${onLineUsers}" var="onLineUsers">
<tr>
<td>${onLineUsers.username }
</td>
<td>${onLineUsers.password }
</td>
</tr>
<br/>
</c:forEach>
</body>
</html>
0回答
相关分类