You are currently browsing the Philipp Meier's weblog posts tagged: jsr


researchnews

Where is inversion of control in JSR 296 (Swing Application Framework)?

JSR-296 will provide us with nice ressource management. You can get property settings like label texts, colors and other properties from ressource files easily:

ApplicationContext ctxt = ApplicationContext.getInstance();  
ResourceManager mgr = ctxt.getResourceManager();
resource = mgr.getResourceMap(HelloWorld.class);
String helloText = (String) resource.getObject("helloLabel", String.class);

But… what is this ApplicationContext.getInstance() static method call? Where is dependency injection? Look into the API documentation of ApplicationContext: it’s a global service locator. That means it provides a fixed bunch of services which are accessible by a singleton instance. You can of course use aggregation, sub-classing and delegation to extend it’s abilities but dependency injection is the train everyone jumps onto, ain’t it?

There is another issue that puzzles me: where are the interfaces? A framework whithout any interface? It’s even worse, ApplicationContext returns instances of concrete classes, not even abstract classes. So you’ll always get an instance of class RessourceManager. I you like to provide your own, you can only sub-class it, at least, RessourceManager is not final.

Can I have some dependeny injection, please? Picocontainer, Guice or Spring, perhaps? Yes, I can but it would be more nice, if RessourceManager, ActionManager and all other services provided by the framework would be interfaces and I could use any implemention I wish.

By the way, there is some dependency injection in the framework: you can inject property values into any awt component with RessourceManager.injectComponent. I hope the method name is not final yet, because I expected an component to be injected into some other instance, not something to be injected into a component.


Bear