Code generation tools for creating for-real ClientApp's using Go/JNI. Currently just a usable POC, if you're doing everything right it works perfectly and it's reasonably simple. In the future, the goal is foolproof and automatic.

Credit: https://github.com/sridharv/gojava for figuring out how to hack gomobile bind and enable this technique.

Usage: First, adapt your application so that it can be controlled by the I2P ClientAppManager by implementing this interface:

type ClientApp interface {
	GetDisplayName() string
	GetName() string
	GetState() ClientAppState
	GetClientState() int
	StartupClient()
	Shutdown()
}

in your Go application. Once you have done that, import the library:

import "i2pgit.org/idk/clientapp"

and call clientapp.GenerateJava(&ExampleClientApp) during your code generation phase to generate the .java wrapper. This small script will work:

//go:build generate
// +build generate

package main

import (
	"io/ioutil"

	. "i2pgit.org/idk/clientapp"
)

func main() {
	ioutil.WriteFile(ClientAppName()+".java", []byte(GenerateJava(&ExampleClientApp{})), 0644)
}

Which you can call by adding the a go generate to your source file:

//go:generate go run --tags=generate i2pgit.org/idk/clientapp/cmd

Build your application and generate any .jar files for your Go library using go build or gojava build first. Then, run go generate. You should end up with a file named ExampleClientApp.java in the build directory. The hard part's over.

Copy the .jar file containing your JNI bindings and your Go library to your classpath. Then, copy the generated .java file to the desired location in your codebase. Now you can use your Go ClientApp from Java with real state tracking, you can call Go functions from Java and with a little more effort, call Java functions from Go.

Likely application: Yggdrasil plugin. IPFS plugin. Syndie plugin. VPN plugin? Syncthing plugin? Really a ton of stuff.