Why would you need a library for that?
You can implement shaders in less than 50 lines of code.
The process for a shader: Generate an id for the shader, attach source, compile, check if successfully compiled(, if not log the shader's infolog).
For a shader program: Generate an id, attach shaders, link, check if successfully linked(, if not print the program's infolog), detach and delete shaders, optionally validate the program.
It might seem scary at first written out like that but it is actually pretty simple.
Sorry for not providong code examples but I'm currently on mobile.
Edit: Oh, you mean pure Java as Java2D? In that case you can't use shaders since those are part of OpenGL.