//HttpSession监听
public interface HttpSessionActivationListener extends EventListener { 

    /** Notification that the session is about to be passivated.*/
	//session无效监听
    public void sessionWillPassivate(HttpSessionEvent se);
    /** Notification that the session has just been activated.*/
    //session有效监听
    public void sessionDidActivate(HttpSessionEvent se);
} 

//session 属性监听
public interface HttpSessionAttributeListener extends EventListener {
	/** Notification that an attribute has been added to a session. Called after the attribute is added.*/
	//属性增加监听
    public void attributeAdded ( HttpSessionBindingEvent se );
	/** Notification that an attribute has been removed from a session. Called after the attribute is removed. */
    //属性删除监听
    public void attributeRemoved ( HttpSessionBindingEvent se );
	/** Notification that an attribute has been replaced in a session. Called after the attribute is replaced. */
    //属性替换监听
    public void attributeReplaced ( HttpSessionBindingEvent se );

}