Developing Event Listeners

A listener can be used to monitor and react to events in a servlet's life cycle by defining methods that get invoked when life cycle events occur. In this way, you can keep track of events such as application context initialization or destruction, session creation, and so on, and can react accordingly to them.

Application event listeners are classes that implement one or more of the servlet event listener interfaces. Servlet event listeners support notification for state changes in the ServletContext and HttpSession objects, specifically:

• Servlet context listeners are used to manage resources or state held at Virtual Machine level for the application.

• HTTP session listeners are used to manage state or resources associated with a series of requests made in a Web application from the same client or user.