I've started a MIT licensed java implementation of a Stratum client.

Its my first check in (i.e. not even 0.0.1 yet!) that I've tested it with some dogecoin pool servers and it seems ok, but it has not undergone any serious production or load testing yet (in particular I've not gone over it with any stress testing for synchonisation yet so there might be some concurrency bugs to be worked out). 

It is designed to be fairly self contained and uses a hopefully simple to use observer pattern for call backs into calling-code.

https://github.com/matt1/stratum-client-java