7.7. Using built-in controllers

I’ve generally used the terms controller and handler interchangeably in this book. A controller is a specialized form of handler that implements the Controller interface directly or indirectly. A handler in Spring is any object that’s responsible for handling any type of request (not necessarily web requests); a handler doesn’t need to extend or implement any Spring-specific class or interface.

Controllers are special beans in Spring Portlet MVC that implement the request-handling functionality of the portlet. The HelloWorldController controller is an example of a handler that directly implements the Controller interface.