java-COM interop: Implement COM interface in Java

Question

How can I implement a vtable COM interface in java?

In the old days, I'd use the Microsft JVM, which had built in java-COM interop. What's the equivalent for a modern JRE?

Answers to a similar SO question proposed JACOB. I've looked at JACOB, but that is based on IDispatch, and is aimed at controlling Automation serers. The COM interfaces I need are custom vtable (extend IUnknown), e.g. IPersistStream, IOleWindow, IContextMenu etc.

For my use case, I could implement all the COM specifics in JNI, and have the JNI layer call corresponding interfaces in java. But I'm hoping for a less painful solution.

It's for an open source project, so open source alternatives are preferred.

EDIT: Com4j looks promising. Looking through the available docs, it doesn't seem to support registering a IClassFactory so the COM object (in java) can be instantiated by non-java clients.

Answer 1

Com4J may be what you need. From the homepage:

Binds directly to the vtable interface (not IDispatch) for improved performance and broader support for more COM interfaces.