監聽器的應用一(統計線上人數)
1.web,xml配置
2.監聽類的配置
3.jsp頁面的顯示
web,xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<display-name>Archetype Created Web Application</display-name>
<!-- 掃描載入配置檔案 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
classpath:spring/applicationContext.xml,
classpath:spring/applicationContext-dataSource.xml
</param-value>
</context-param>
<!--log4j配置檔案開始-->
<context-param>
<param-name>log4jConfigLocation</param-name>
</context-param>
<listener>
<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>
<!-- webservice釋出的監聽器 -->
<listener-class>com.fxb.listener.MyListener</listener-class>
</listener>
<!-- 統計線上人數 監聽器 -->
<listener>
<listener-class>com.fxb.listener.MyListener2</listener-class>
</listener>
<!-- post方式提交 統一字元編碼過濾器 -->
<filter>
<filter-name>characterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- springmvc攔截所有的請求交由各個處理器 -->
<servlet>
<servlet-name>springMvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring/applicationContext-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springMvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
</web-app>
MyListener2.java
package com.fxb.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import org.springframework.web.context.ContextLoaderListener;
public class MyListener2 implements HttpSessionListener{
private int userNumber = 0;
public void sessionCreated(HttpSessionEvent arg0) {
userNumber++;
arg0.getSession().setAttribute("userNumber", userNumber);
}
public void sessionDestroyed(HttpSessionEvent arg0) {
userNumber--;
arg0.getSession().setAttribute("userNumber", userNumber);
}
}
jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>儲存結果</title>
<meta name="description" content="overview & stats" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
</head>
<body>
線上人數：<%=session.getAttribute("userNumber") %><br/>
<a href="<%=basePath%>user/getList?name=付曉波">我是付曉波</a>
</body>
</html>