For what it was worth, I had a project like this some time ago. It was pretty easy to auto-generate JNI wrappers. I think we had about 350 export functions. It took us about 3 hours to build a script to automatically generate a wrapper (sorry, do not use a convenient script or I would publish it).
We ourselves did not write almost C ++ code, but it required an understanding of how JNI works ... This is a really good opportunity / training project - if you have time, do not be afraid of JNI - you will be amazed how much you learn about how the jvm works ...
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