main.go

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"

	flag "github.com/spf13/pflag"
)

const cmdStr = `#!/bin/sh
exec java %s -jar "$0" "$@"
exit $?
`

func main() {
	var (
		exeFileName string
		javaOptions string
	)
	flag.StringVar(&exeFileName, "name", "", "exe file name")
	flag.StringVar(&javaOptions, "jop", "", "java options")
	flag.Parse()

	if len(flag.Args()) == 0 {
		log.Fatal("Not enough arguments. ex)jarexe standalone.jar")
	}

	jarFileName := flag.Args()[0]
	jarFile, err := os.Open(jarFileName)
	if err != nil {
		log.Fatalf("error: %s", err.Error())
	}
	defer jarFile.Close()

	if exeFileName == "" {
		exeFileName = filepath.Base(jarFileName)
		if ext := filepath.Ext(exeFileName); ext == ".jar" {
			exeFileName = exeFileName[:len(exeFileName)-4]
		}
	}

	shStr := fmt.Sprintf(cmdStr, javaOptions)

	reader := io.MultiReader(strings.NewReader(shStr), jarFile)

	b, err := ioutil.ReadAll(reader)
	if err != nil {
		log.Fatalf("error: %s", err.Error())
	}
	err = ioutil.WriteFile(exeFileName, b, os.ModePerm)
	if err != nil {
		log.Fatalf("error: %s", err.Error())
	}
}