This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
The only methods that Struts will call on your plugin are init() and destroy(). If you have other methods, the only way they will get called is if you locate the object and call them yourself. For example, you could make the object a singleton and provide it with a static getInstance() method that returns an instance of the class. Once you have a reference to the object, you can call whatever methods you want.