--Listener （二）Listener使用

来源：互联网发布：公司网络屏蔽qq 编辑：程序博客网时间：2024/05/16 17:44

在这里，编写了三个listener，一个inde.jsp和a.jsp。
HelloServletContextListener

package com.tuxianchao.listener;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;/* * Listener */public class HelloServletContextListener implements ServletContextListener {    @Override    public void contextDestroyed(ServletContextEvent servletContextEvent) {        // servletContext对象被创建的时候调用（当前web应用加载的时候被Servlet容器调用）        System.out.println("ServletContext被销毁..." + servletContextEvent.getServletContext());    }    @Override    public void contextInitialized(ServletContextEvent servletContextEvent) {        // servletContext对象被销毁的时候调用（当前web应用卸载的时候被Servlet容器调用）        System.out.println("ServletContext被创建..." + servletContextEvent.getServletContext());    }}

HelloServletRequestListener

package com.tuxianchao.listener;import javax.servlet.ServletRequestEvent;import javax.servlet.ServletRequestListener;public class HelloServletRequestListener implements ServletRequestListener {    @Override    public void requestDestroyed(ServletRequestEvent arg0) {        // TODO Auto-generated method stub        System.out.println("request被销毁...");    }    @Override    public void requestInitialized(ServletRequestEvent arg0) {        // TODO Auto-generated method stub        System.out.println("request被创建..");    }}

HelloHttpSessionListener

package com.tuxianchao.listener;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;public class HelloHttpSessionListener implements HttpSessionListener {    @Override    public void sessionCreated(HttpSessionEvent arg0) {        // TODO Auto-generated method stub        System.out.println("Session被创建..");    }    @Override    public void sessionDestroyed(HttpSessionEvent arg0) {        // TODO Auto-generated method stub        System.out.println("Session被销毁...");    }}

index.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"    pageEncoding="ISO-8859-1"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Insert title here</title></head><body>    <h2>Index</h2>    <a href="a.jsp">A PAGE</a></body></html>

a.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"    pageEncoding="ISO-8859-1"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Insert title here</title></head><body>    <h2>AAA PAGE</h2></body></html>

web.xml中的配置：

<!-- 配置Listener -->    <listener>        <listener-class>com.tuxianchao.listener.HelloServletContextListener</listener-class>    </listener>    <listener>        <listener-class>com.tuxianchao.listener.HelloServletRequestListener</listener-class>    </listener>    <listener>        <listener-class>com.tuxianchao.listener.HelloHttpSessionListener</listener-class>    </listener>

当tomcat启动后，web应用被加载，创建ServletContext对象，紧接着访问默认主页index.jsp，创建request对象，由于第一次访问会创建一个HttpSession对象，当请求完成后（响应返回），request对象会销毁。
这里写图片描述

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