If an application makes extensive use of Spring, it can be convenient to manage all the classes in one location – the Spring configuration. Remember that Actions do not need to implement a special interface. Actions can also be POJOs that are not tied to
Struts or the web layer in any way.

We might also want to apply more complex AOP or Spring-enabled technologies, such as Acegi, to our Action objects.

For more, see Initializing Actions from Spring.