How to do some task when data is added or removed from the session when user login or logout ?

Scenario 1

I have an attribute class

Class User{

  String name;

  String address;

  String phoneNo;

  boolean isLogged;

}

This class will be added to the session when user logs in and removed from the session when user logs out.

I want its isLogged flag to be changed when user login and logs out.

Using which listener I can do it ?

Solution

Use listener "javax.servlet.http.HttpSessionBindingListener"

It causes an object to be notified when it is bound to or unbound from a session.

The object is notified by an HttpSessionBindingEvent object.

Method Summary

void valueBound(HttpSessionBindingEvent event)

          Notifies the object that it is being bound to a session and identifies the session.

void valueUnbound(HttpSessionBindingEvent event)

          Notifies the object that it is being unbound from a session and identifies the session.

Scenario 2

A class implements HttpSessionBindingListener and an object of that class is in session.

If you invalidate the session, which method of that class will be invoked ?

Solution

When a session is invalidated, all the session attributes are unbound from the session.

If any attribute implements HttpSessionBindingListener, the valueUnbound() method will be called on the attribute.