Is there a means of executing code during the startup of Apache Tomcat 6.x to perform initialization routines, etc.?

Question

I want to initialize a global instance of a class before my Tomcat server completes startup and begins to offer my servlets. If this service somehow fails initialization, I

Answer 1

Each web application has a ServletContext associated with it. The ServletContext object is created when the application is started and is destroyed when the application is shut down. A ServletContext has a global scope and is similar to a global variable in an application.

http://www.javabeat.net/tips/178-servletcontextlistener-example.html

complete explanation here

http://onjava.com/pub/a/onjava/2001/04/12/listeners.html