One of the other major features included in the Portlet 2.0 specification is the ability to add filters to portlets. Filters are Java classes that are used to modify requests and responses before and after the life cycle method of a portlet is invoked.
Portlet filters behave in the same manner as a servlet filter except for one major difference. Servlet handles requests only with a single method,
service() . Hence, there is only a single type of servlet filter that wraps around the method processing. However, there are four life cycle methods in portlet filters, resulting in four types of Portlet filters.
The specification defines the following methods:
javax.portlet.filter.ActionFilter:Filters requests to