Ah, but by the way, if you installed the official driver from their website, Java might not find it. All you have to do, deactivate this process in the System's Device Manager:
HID-compliant game controller
And then kill the following process with the Task Manager:
I think, these processes are required for some games or if you want to use the Space Mouse to navigate in Windows. And then that is the problem: Windows captures the events, and Java does not get them anymore. So, that is my theory ;-)
If you need the space mouse only for Java3D, you might not even need to install the driver, because e.g. Windows 8 seems to automatically install one in the background which is sufficient for Java3D.