No, there isn't a direct Java Client. You could use Tuxedo and Jolt to access BMQ, but that's a little bit of a circuitous route. Alternatively you could use JNI, although I don't know if that would be supported. Can you describe what it is you are trying to do?
Oracle Tuxedo Chief Architect
I was simply fielding the question in case one has become available over the last few years that I wasn't aware of.
We are in fact using JNI for a few of our Java clients. Unfortunately, as described in another thread within this forum, I would like to both read and write to the same queue using different Java threads which is where we are having problems.