HttpSessionActivationListener

public class Person implements HttpSessionActivationListener, Serializable {

    public void sessionDidActivate(HttpSessionEvent arg0) {

       System.out.println("session从硬盘读入内存了");

    }

    public void sessionWillPassivate(HttpSessionEvent arg0) {

       System.out.println("session被存到硬盘中去了");

    }

}

<%

session.setAttribute("person",new Person());

%>

<Context>

<Manager className="org.apache.catalina.session.PersistentManager" maxIdleSwap="1">

<Store className="org.apache.catalina.session.FileStore" directory="class3g"/>

</Manager>

</Context>