Filter-III
All user defined filters should be subclasses of abstract class Filter.
All user defined filters must provide a public no-arg constructor, so that they can be automatically instantiated by a server. The normal programmatic instantiation process(Class.newInstance()) does not allow arguments to be passed to a constructor. See the details of Introspection and Reflection documents from http://www.sun.com
The main thing to do is to implement a method performFilter()