监听器[用于监听ServletRequest对象的产生和销毁] 学习笔记

import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;

//监听器[用于监听ServletRequest对象的产生和销毁]
public class MyServletRequestListener implements ServletRequestListener {
    //产生
    public void requestInitialized(ServletRequestEvent sre) {
        System.out.println("requestInitialized()");
    }
    //销毁
    public void requestDestroyed(ServletRequestEvent sre) {
        System.out.println("requestDestroyed()");
    }
}

<listener>
<listener-class>cn.itcast.web.listener.MyServletRequestListener</listener-class>
</listener>

    >>创建和销毁：ServletContextListener，Web容器部署时产生，Web容器重新部署时销毁原ServletContext对象
            >>属性变化：ServletContextAttributeListner
        application.setAttirbute("name","jack")
        setAttribute("name","liw")
        removeAttribute("name")