j-Interop is a Java Open Source library (LGPL) that implements the DCOM wire protocol (MSRPC) to enable development of Pure, Bi-Directional, Non-Native Java applications which can interoperate with any COM component.
JCOM is a Java to COM bridge library. With JCOM you can call a COM object from Java as if it were a Java object without having to deal with the internals of JNI.