I would encourage you to take a look at Eclipse RCP project.
But instead of taking the "Classic RCP" route, you would do much better to look at the Eclipse 4 and the e4 incubator project it has graduated from.
Eclipse 4 RCP should feel quite familiar to you in spirit if not in API, if you come from the Spring background.
It has service oriented architecture built on top of very excellent Equinox OSGi container, that feels a lot like Spring, if you use Declarative Services.
It has also very clean model based application layout definition that opens up flexibility and composability that can easily top any web framework I have ever worked with (which is admittedly not saying much).
When writing UI components, you can easily rely on easy and functional DI, allowing to keep coupling to the framework as low as absolutely necessary.