JNIGI

Java Native Interface Golang Interface.

A package to access Java from Golang code. Can be used from a Golang executable or shared library. This allows for Golang to initiate the JVM or Java to start a Golang runtime respectively.

Install

Run the install script with the JDK path location.

./install.sh <root path of jdk>

On Windows you can use install.bat.

This script sets the CGO_CFLAGS to add the C header includes. You can do this your self and run go install, and setting these is needed for go test.

Finding JVM at Runtime

Set JAVA_HOME environment variable to the JDK path location, from here JNIGI will look for the JVM library installed in the JRE.

Notes

Signals

The JVM calls sigaction, Golang requires that SA_ONSTACK flag be passed. Without this Golang will not be able to print the exception information eg. type, stack trace, line number. On Linux a solution is using LD_PRELOAD with a library that intercepts sigaction and adds the flag. (Code that does this: https://gist.github.com/timob/5d3032b54ed6ba2dc6de34b245c556c7)

Status

• Has been used in Golang (many versions since 1.6) executable multi threaded applications on Linux / Windows.
• Tests for main functions tests are present.
• Documentation needed.

Changes

• 2019-05-29 Better multiplatform support, dynamic loading of JVM library.
• 2016-08-01 Initial version.

Example

package main

import (
	"fmt"
	"github.com/timob/jnigi"
	"log"
)

func main() {
    _, env, err := jnigi.CreateJVM(jnigi.NewJVMInitArgs(false, true, jnigi.DEFAULT_VERSION, []string{"-Xcheck:jni"}))
    if err != nil {
        log.Fatal(err)
    }
    obj, err := env.NewObject("java/lang/Object")
    if err != nil {
    	log.Fatal(err)
    }
    v, err := obj.CallMethod(env, "hashCode", jnigi.Int)
    if err != nil {
    	log.Fatal(err)
    }
    fmt.Printf("object hash code: %d\n", v.(int))
}