Servlet Listener

package com.my;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ServletListener implements ServletContextListener {
    public ServletListener() {}
    
    // context初始化时激发
    public void contextInitialized(ServletContextEvent e) {
        System.out.println("Servlet Initialiszed.");
    }
    
    // context删除时激发
    public void contextDestroyed(ServletContextEvent e) {
        System.out.println("Servlet Destroyed.");
    }
    
    // 创建一个 session时激发
    public void sessionCreated(HttpSessionEvent e) {
        System.out.println("Session Created.");
    }
    
    // 当一个 session失效时激发
    public void sessionDestroyed(HttpSessionEvent e) {
        System.out.println("Session destroyed.");
    }
    
    // 设置 context的属性，它将激发attributeReplaced或attributeAdded方法
    public void setContext(HttpSessionEvent e) {
        //
    }
    
    // 增加一个新的属性时激发
    public void attributeAdded(ServletContextAttributeEvent e) {
        //
    }
    
    // 删除一个新的属性时激发
    public void attributeRemoved(ServletContextAttributeEvent e) {
        //
    }
    
    // 属性被替代时激发
    public void attributeReplaced(ServletContextAttributeEvent e) {
        //
    }
}

    <listener> 
        <listener-class>com.my.ServletListener</listener-class> 
    </listener>