Servlet3.0 Listener

 package com.lee.listener;

 import javax.servlet.ServletContextEvent;
 import javax.servlet.ServletContextListener;
 import javax.servlet.annotation.WebListener;

 /**
  * Application Lifecycle Listener implementation class GetConnListener
  * ServletContextListener :用于监听Web应用启动和关闭
  * ServletContextAttributeListener: 用于监听ServletContxt范围(appliaction)内属性的改变
  *
  *
  * ServletRequestListener:用于监听用户的请求
  * SerlvetRequestAttributeListener:用于监听ServletReqeust范围(request)内属性的改变
  *
  * HttpSessionListener:用于监听用户sesion的开始和结束
  * HttpSessionAtributeListener:用于监听HttpSession范围(session)内属性的变化.
  */
 @WebListener
 public class GetConnListener implements ServletContextListener {

     /**
      * Default constructor.
      */
     public GetConnListener() {
         // TODO Auto-generated constructor stub
     }

     /**
      * @see ServletContextListener#contextInitialized(ServletContextEvent)
      */
     public void contextInitialized(ServletContextEvent arg0) {
         // TODO Auto-generated method stub
         System.out.println("Web 应用初始化了");

     }

     /**
      * @see ServletContextListener#contextDestroyed(ServletContextEvent)
      */
     public void contextDestroyed(ServletContextEvent arg0) {
         // TODO Auto-generated method stub
         System.out.println("Web 应用关闭了");
     }

 }

 package com.lee.listener;

 import javax.servlet.ServletContext;
 import javax.servlet.ServletContextAttributeEvent;
 import javax.servlet.ServletContextAttributeListener;
 import javax.servlet.annotation.WebListener;

 /**
  * Application Lifecycle Listener implementation class MyServletConnextAtrributeListener
  *
  */
 @WebListener
 public class MyServletConnextAtrributeListener implements ServletContextAttributeListener {

     /**
      * Default constructor.
      */
     public MyServletConnextAtrributeListener() {
         // TODO Auto-generated constructor stub
     }

     /**
      * @see ServletContextAttributeListener#attributeAdded(ServletContextAttributeEvent)
      */
     public void attributeAdded(ServletContextAttributeEvent arg0) {
        ServletContext application=arg0.getServletContext();
        String name=arg0.getName();
        Object value=arg0.getValue();
        System.out.println(application+"范围内添加了名为:"+name+",值为"+value+"的属性");
     }

     /**
      * @see ServletContextAttributeListener#attributeReplaced(ServletContextAttributeEvent)
      */
     public void attributeReplaced(ServletContextAttributeEvent arg0) {
         ServletContext application=arg0.getServletContext();
         String name=arg0.getName();
         Object value=arg0.getValue();
         System.out.println(application+"范围内名为:"+name+",值被替换为"+value+"的属性");
     }

     /**
      * @see ServletContextAttributeListener#attributeRemoved(ServletContextAttributeEvent)
      */
     public void attributeRemoved(ServletContextAttributeEvent arg0) {
         ServletContext application=arg0.getServletContext();
         String name=arg0.getName();
         Object value=arg0.getValue();
         System.out.println(application+"范围内名为:"+name+",值为"+value+"的被删除了!");
     }

 }

 package com.lee.listener;

 import java.util.HashMap;
 import java.util.Map;

 import javax.servlet.ServletContext;
 import javax.servlet.annotation.WebListener;
 import javax.servlet.http.HttpSession;
 import javax.servlet.http.HttpSessionEvent;
 import javax.servlet.http.HttpSessionListener;

 /**
  * Application Lifecycle Listener implementation class OnLineListener
  *
  */
 @WebListener
 public class OnLineListener implements HttpSessionListener {

     /**
      * Default constructor.
      */
     public OnLineListener() {
         // TODO Auto-generated constructor stub
     }

     /**
      * @see HttpSessionListener#sessionCreated(HttpSessionEvent)
      */
     public void sessionCreated(HttpSessionEvent arg0) {
         // TODO Auto-generated method stub

         HttpSession session=arg0.getSession();
         //获取sessionid
         String sessionid=session.getId();
         ServletContext application=session.getServletContext();
         if(session.isNew()){//如果是一次新的回话
             String user=(String)session.getAttribute("user");
             user=(user==null)? "游客":user;
             Map<String,String> online=(Map<String,String>)application.getAttribute("online");
             if(online==null){
                 online=new HashMap<String,String>();
             }
             online.put(sessionid, user);
             application.setAttribute("online", online);

         }


     }

     /**
      * @see HttpSessionListener#sessionDestroyed(HttpSessionEvent)
      */
     public void sessionDestroyed(HttpSessionEvent arg0) {
         // TODO Auto-generated method stub
         HttpSession session=arg0.getSession();
         ServletContext application=session.getServletContext();
         String sessionid=session.getId();
         Map<String,String> online=(Map<String,String>)application.getAttribute("online");
         if(online!=null)
             online.remove(sessionid);
         application.setAttribute("online",online);
     }

 }

 package com.lee.listener;

 import javax.servlet.ServletRequest;
 import javax.servlet.ServletRequestAttributeEvent;
 import javax.servlet.ServletRequestAttributeListener;
 import javax.servlet.ServletRequestEvent;
 import javax.servlet.ServletRequestListener;
 import javax.servlet.annotation.WebListener;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpSession;

 /**
  * Application Lifecycle Listener implementation class RequestListenter
  *
  */
 @WebListener
 public class RequestListenter implements ServletRequestListener, ServletRequestAttributeListener {

     /**
      * Default constructor.
      */
     public RequestListenter() {
         // TODO Auto-generated constructor stub
     }

     /**
      * @see ServletRequestListener#requestDestroyed(ServletRequestEvent)
      */
     public void requestDestroyed(ServletRequestEvent arg0) {
         // TODO Auto-generated method stub
          System.out.println("请求被初始化");
     }

     /**
      * @see ServletRequestAttributeListener#attributeAdded(ServletRequestAttributeEvent)
      */
     public void attributeAdded(ServletRequestAttributeEvent arg0) {
         // TODO Auto-generated method stub
         ServletRequest request=arg0.getServletRequest();
         String name=arg0.getName();
         Object value=arg0.getValue();
         System.out.println(request+"范围内添加了名为"+name+",值为"+value+"的属性");

     }

     /**
      * @see ServletRequestAttributeListener#attributeRemoved(ServletRequestAttributeEvent)
      */
     public void attributeRemoved(ServletRequestAttributeEvent arg0) {
         ServletRequest request=arg0.getServletRequest();
         String name=arg0.getName();
         Object value=arg0.getValue();
         System.out.println(request+"范围内删除了名为"+name+",值为"+value+"的属性");
     }

     /**
      * @see ServletRequestAttributeListener#attributeReplaced(ServletRequestAttributeEvent)
      */
     public void attributeReplaced(ServletRequestAttributeEvent arg0) {
         ServletRequest request=arg0.getServletRequest();
         String name=arg0.getName();
         Object value=arg0.getValue();
         System.out.println(request+"范围内替换了名为"+name+",值为"+value+"的属性");
     }

     /**
      * @see ServletRequestListener#requestInitialized(ServletRequestEvent)
      */
     public void requestInitialized(ServletRequestEvent arg0) {
        HttpServletRequest request=(HttpServletRequest)arg0.getServletRequest();
        HttpSession session =request.getSession();
        String sessionid=session.getId();
        String ip=request.getRemoteAddr();
        String page=request.getRequestURI();
        String user=(String)session.getAttribute("user");
        user=(user==null)?"游客":user;
        try {

            //将用户登录存入 数据库  通过sessionid 查询.

         } catch (Exception e) {
             // TODO: handle exception
         }


        System.out.println("---发出---"+request.getRequestURI()+
                "Addr:"+request.getRemoteAddr()+
                "Host:"+request.getRemoteHost()+
                "Port:"+request.getRemotePort()+
                "User:"+request.getRemoteUser()+
                "SessionId:"+request.getRequestedSessionId());
        System.out.println("请求被初始化");
     }

 }