javax.servlet.*,javax.servlet.http.*包应用-Listener

Listener如其名所意,它是一个事件监听器.在以上的两个包里包含ServletContextListener  ServletRequestAttributeListener
ServletRequestListener  HttpSessionActivationListener  HttpSessionAttributeListener  HttpSessionBindingListener 六种监听接口,只需要实现该接口的方法就可以监听对应对象的事件.例如ServeletContextListener监听的对象就是ServeletContext,监听的事件包括contextInitialized和contextDestroyed,ContextInitialized是在ServletContext的其他资源加载之前触发的事件.而contextDestoryed则是ServletContext被Destoryed的事件.部署这些Listener只要在Web.xml里面配置即可.如下所示:

 

<listener>
      <listener-class>
        com.test.MyServletContextListener
      listener-class>
    listener>
    <listener>
      <listener-class>com.test.MySessionListenerlistener-class>
    listener>

类的代码如下:

package com.test;

import java.util.Date;
import javax.servlet.http.HttpSessionListener;
import javax.servlet.http.HttpSessionEvent;

public class MySessionListener implements HttpSessionListener{
  public void sessionCreated(HttpSessionEvent event){
     System.out.println(new Date());
     System.out.println("session has been created");
  }

  public void sessionDestroyed(HttpSessionEvent event){
     System.out.println("session has been closed");
  }
}

package com.test;

import javax.servlet.ServletContextListener;
import javax.servlet.ServletContextEvent;
public class MyServletContextListener implements ServletContextListener{
  public void contextInitialized(ServletContextEvent sce){
      System.out.println("...........ContextInitialized.............");
  }

  public void contextDestroyed(ServletContextEvent sce){

  }
}

java 代码

java 代码

xml 代码