Here is what xFunction for Windows is all about:
The xFunction library is the universal solution for integration of Java code with code written in other languages, superior in many aspects to Java Native Interface (JNI). With xFunction, you no longer need to implement those ugly native methods. Instead, you extend and instantiate xFunction classes to create conventional Java objects representing external functions, data structures, pointers, and callbacks. All necessary data conversions and external function calls are done seamlessly by the xFunction library. Using xFunction, you may invoke any operating system API call or function from any DLL or shared library in a natural and convenient manner.
xFunction allows you to achieve the highest levels of code reuse without translating any source code to Java and/or writing cumbersome JNI wrappers.