“Elmo is a JavaBean pool implementation for the Sesame RDF repository. Specifically, Elmo is a subject-oriented RDF Bean pool that allows JavaBeans to be cast to different roles and provides a unique context specific view of the subject.”
Basically, you can annotate your classes with url’s describing the RDF namespace of the class or property. You can then use SPARQL to query/retrieve the beans, and serialize them to/from XML. Serialization can be acheived through the Sesame framework.
Additionally, there is another project, JRDF, that builds upon Sesame and Jena. I have yet to use it, but sounds like in encompasses the best of all worlds.