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")