Where did your Java architecture go?. Classycle might have good answers for you. It is easier to configure than jdepend which was the de facto open source cycle analyzer before and which you might still want to check out.
Here is how to analyze the spring core jar for example. Even though the below uses plain command line, an eclipse and maven plugins are available at the moment so you might want to check those out. Specially you should build ddf files to enforce your architectural layers and make sure the build fails if it is violated.