Listener

所有的监听器都是接口，介绍六大监听器；分为生命周期监听ServletContextListener，HttpSessiontListener,ServletRequestListener,每个监听器有两个方法 init,和destory

servletContextListener

public class MyListener implements ServletContextListener {

@Override
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("i am destory");

}

@Override
public void contextInitialized(ServletContextEvent arg0) {

System.out.println("I am comming");
}

}

 

三大属性监听器ServletContextAttributeListener，ServletRequestAttributeListener，HttpSessionAttributeListener

有三个方法：各个监听器对应的add,replace,remove方法，用于监听属性的改变

class Css implements ServletRequestAttributeListener{

@Override
public void attributeAdded(ServletRequestAttributeEvent srae) {
// TODO Auto-generated method stub

}

@Override
public void attributeRemoved(ServletRequestAttributeEvent srae) {
// TODO Auto-generated method stub

}

@Override
public void attributeReplaced(ServletRequestAttributeEvent srae) {
// TODO Auto-generated method stub

}

}