Another form to check the attributes of a session is through session binding. We can extend any object that will get in the session as an attribute and check it each time it is managed. The javax.servlet.http.HttpSessionBindingListener interface provides two methods for the object:

• The valueBound method starts when the MyAttribute object is taken through the session.setAttribute(...) method
• The valueUnbound starts when the session.removeAttribute(...) method is executed on the MyAttribute object

Here a sample of Session binding listener implementation:

public class MyAttribute implements HttpSessionBindingListener {
 private static final Logger logger = getLogger(MyAttribute.class.getName());
   @Override
 public void valueBound(HttpSessionBindingEvent event) {
      logger.info("MyAttribute.valueBound: " + event.getName());
   }
   @Override
 public void valueUnbound(HttpSessionBindingEvent event) {
      logger.info("MyAttribute.valueUnbound: " + event.getName());
   }
}