JAVA-EE监听器Listener监听request和session以及application------计算机网络经典

谁践踏了优雅 2024-02-21 12:12 12阅读 0赞

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletContextEvent;
>     import jakarta.servlet.ServletContextListener;
>     import jakarta.servlet.annotation.WebListener;
>     
>     @WebListener
>     public class MyListener implements ServletContextListener
>     //实现ServletContextListener接口
>     {
>         //现在这个监听器主要监听的时servletContext的状态
>         //所有监听器中的方法都不需要我们调用
>         //由服务器来调用,但事件发生后,被服务器调用
>         @Override
>         public void contextInitialized(ServletContextEvent sce) {
>             //这个方法在servletContext创建的时候调用
>             System.out.println("servletContext创建了");
>             //这个对象随服务器启动创建
>         }
>     
>         @Override
>         public void contextDestroyed(ServletContextEvent sce) {
>             //这个在ServletContext被销毁的时候调用
>             System.out.println("servletContext销毁了");
>             //这个对象随服务器关闭销毁
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletContextEvent;
>     import jakarta.servlet.ServletContextListener;
>     import jakarta.servlet.annotation.WebListener;
>     
>     @WebListener
>     public class MyListener implements ServletContextListener
>     //实现ServletContextListener接口
>     {
>         //现在这个监听器主要监听的时servletContext的状态
>         //所有监听器中的方法都不需要我们调用
>         //由服务器来调用,但事件发生后,被服务器调用
>         @Override
>         public void contextInitialized(ServletContextEvent sce) {
>             //这个方法在servletContext创建的时候调用
>             System.out.println("servletContext创建了");
>             //这个对象随服务器启动创建
>         }
>     
>         @Override
>         public void contextDestroyed(ServletContextEvent sce) {
>             //这个在ServletContext被销毁的时候调用
>             System.out.println("servletContext销毁了");
>             //这个对象随服务器关闭销毁
>         }
>     }

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletRequestEvent;
>     import jakarta.servlet.ServletRequestListener;
>     import jakarta.servlet.annotation.WebListener;
>     
>     @WebListener
>     public class MyRequestListener implements ServletRequestListener
>     {
>         @Override
>         public void requestDestroyed(ServletRequestEvent sre) {
>             System.out.println("request销毁");
>         }
>     
>         @Override
>         public void requestInitialized(ServletRequestEvent sre) {
>             System.out.println("request创建");
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletRequestEvent;
>     import jakarta.servlet.ServletRequestListener;
>     import jakarta.servlet.annotation.WebListener;
>     
>     @WebListener
>     public class MyRequestListener implements ServletRequestListener
>     {
>         @Override
>         public void requestDestroyed(ServletRequestEvent sre) {
>             System.out.println("request销毁");
>         }
>     
>         @Override
>         public void requestInitialized(ServletRequestEvent sre) {
>             System.out.println("request创建");
>         }
>     }

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/L/L")
>     public class SessionC extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             HttpSession session = request.getSession(false);
>             session.invalidate();
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/L/L")
>     public class SessionC extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             HttpSession session = request.getSession(false);
>             session.invalidate();
>         }
>     }

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.annotation.WebListener;
>     import jakarta.servlet.http.HttpSessionEvent;
>     import jakarta.servlet.http.HttpSessionListener;
>     
>     @WebListener
>     public class MySession implements HttpSessionListener
>     {
>         @Override
>         public void sessionCreated(HttpSessionEvent se) {
>             System.out.println("session创建了");
>         }
>     
>         @Override
>         public void sessionDestroyed(HttpSessionEvent se) {
>             System.out.println("session销毁了");
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.annotation.WebListener;
>     import jakarta.servlet.http.HttpSessionEvent;
>     import jakarta.servlet.http.HttpSessionListener;
>     
>     @WebListener
>     public class MySession implements HttpSessionListener
>     {
>         @Override
>         public void sessionCreated(HttpSessionEvent se) {
>             System.out.println("session创建了");
>         }
>     
>         @Override
>         public void sessionDestroyed(HttpSessionEvent se) {
>             System.out.println("session销毁了");
>         }
>     }

>     package com.bjpowernode.oa;
>     
>     public class Test
>     {
>         //静态代码块,类加载时执行,只执行一次
>         //静态代码块用的不多,但是但我们需要在类加载的时候执行一段代码,我们就使用
>         //由此可知,静态代码块就是java程序为程序员预留的一个时间,在类加载时执行代码
>         static
>         {
>             System.out.println("类加载了");
>         }
>     
>         public static void main(String[] args)
>         {
>     
>         }
>     }
> 
>     package com.bjpowernode.oa;
>     
>     public class Test
>     {
>         //静态代码块,类加载时执行,只执行一次
>         //静态代码块用的不多,但是但我们需要在类加载的时候执行一段代码,我们就使用
>         //由此可知,静态代码块就是java程序为程序员预留的一个时间,在类加载时执行代码
>         static
>         {
>             System.out.println("类加载了");
>         }
>     
>         public static void main(String[] args)
>         {
>     
>         }
>     }