第一个监听程序并输出监听内容

秒速五厘米 2022-02-05 06:17 180阅读 0赞

首先简述下在myeclipse 下创建 监听程序的小过程

在 src 下新建个listener 文件夹，然后在此文件夹下 new -> class 然后在点 add 输入 servletContextlistener 确定就OK 了

最后 修改 web.xml 就完成 了

jsp 页面内容

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
    <head>
    <title>ServletContext监听测试页</title>
    </head>
    <body>
    <%
       ServletContext context=pageContext.getServletContext();
       context.setAttribute("id","0001");
       context.setAttribute("name","lihua");
       context.setAttribute("age",10);
       context.setAttribute("name","wanglin");
       context.removeAttribute("name");
       context.removeAttribute("id");
     %>
    </body>
    </html>

监听程序

package listener;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.PrintWriter;
    import java.util.Date;
    import javax.servlet.ServletContext;
    import javax.servlet.ServletContextAttributeEvent;
    import javax.servlet.ServletContextAttributeListener;
    import javax.servlet.ServletContextEvent;
    import javax.servlet.ServletContextListener;
    public class MyServletContextListener implements ServletContextListener,
    		ServletContextAttributeListener {
        private ServletContext context=null;
    	public void contextDestroyed(ServletContextEvent arg0) {
    		logout(":Form ContextListener"+" contestDestroyed()--ServletContext被销毁");
            context=null;
    	}
    	public void contextInitialized(ServletContextEvent arg0) {
    		context=arg0.getServletContext();
    		logout(":Form ContextListener"+" contextInitialized()--ServletContext初始化");
     	}
    	public void attributeAdded(ServletContextAttributeEvent arg0) {
    		logout(":Form ContextAttributeListener"+"增加了一个属性"+arg0.getName()+",值为:"+arg0.getValue());
    	}
    	public void attributeRemoved(ServletContextAttributeEvent arg0) {
    		logout(":Form ContextAttributeListener"+"删除了一个属性"+arg0.getName()+",值为:"+arg0.getValue());
    	}
    	public void attributeReplaced(ServletContextAttributeEvent arg0) {
    		logout(":Form ContextAttributeListener"+"更改了属性值,属性为:"+arg0.getName()+",现值为:"+arg0.getValue());
    
    	}
    
    	private void logout(String message)
        {
        	try {
    			PrintWriter out=new PrintWriter(new FileOutputStream("e:/servletContextLog.txt",true));
    			out.println(new Date()+"::Form ContextListener"+message);
    			System.out.println(new Date()+message);
    			out.close();
    		} catch (FileNotFoundException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
        }
    }

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.MyServletContextListener</listener-class>
    　　</listener>
      <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
      </welcome-file-list>
    </web-app>