How to use Jar file in Golang?

Question

Is it possible to use jar file class methods in Go code. If so than please forward me the link for the same. I have searched the same in

GoDoc/github.com/code.google

But there was no such package build.

Solution 1

It's "possible" only in the extremely pedantic sense that you could theoretically write some sort of JVM environment in Go that can run JVM bytecode that happens to interact with memory allocated by Go.

In any practical sense, Java (and Scala etc) compile in completely different ways to Go and it's not feasible to do this. This is especially complicated by Go having its own runtime which complicates the inverse as well (running Go functions from Java).

If you need to communicate with Java code from Go, I advise looking into RPC, you can launch a Java program as a separate process and cooperatively call methods over your local network. This takes a little effort, but not very much. It's certainly easier than writing the framework to truly invoke Java methods from Go would be.

The other option is to invoke Java programs by using os/exec, having them output to a file or command line, and then reading in that output and parsing it, but that's a lot more fragile than RPC and prone to errors and security holes.

As Evan mentions in the comments, you can use the JNI (Java Native Interface) with a C entrypoint. So using Cgo you can launch the JVM and call Java code. This site seems to have a tutorial on how to set it up in C and C++. I'm not very familiar with using JNI from this direction so I can't really recommend it nor dissuade you from using it. It does introduce a C dependency into your build process though, so be aware of that.

Solution 2

I have a similar usecase. I use kafka as a message bus. The producer is in scala and consumer is a go application. This works seamlessly. Best part of this is, it can scale on any distributed setup.

Comments

[Evan]

The third option is to write a C bridge, using the Java Native Interface (en.wikipedia.org/wiki/Java_native_interface) and CGo (golang.org/cmd/cgo)

[Linear]

@Evan -- I actually wasn't aware that that worked, I thought JNI was like Cgo: it had to be invoked with the Java program as the entry point. I'll add that.

[renier]

The JNI binding generator you linked to has moved to github.com/skanjo/jag

[Admin]

jag appears dead.