// convert normal string to hex bytes string

def string2hex(str: String): String = {

  str.toList.map(_.toInt.toHexString).mkString

}

// convert hex bytes string to normal string

val byteArray: Array[Byte] = List.range(1, 255).map(_.toByte).toArray

val bos = new BufferedOutputStream(new FileOutputStream("test.txt"))

bos.write(byteArray)

bos.close() 

def string2int(hex: String) = {

  hex.sliding(2, 2).map(Integer.parseInt(_, 16)).toArray

}

def test(l: List[Int]) = {

  l.map(_.toChar).mkString

}

import java.io._

val writer = new PrintWriter(new File("test.txt" ))

//writer.write(string2int("cafebabe"))

writer.write(test(List.range(1, 255)))

writer.close()

import scalax.io._

import scalax.io.Resource

FileOutputStream fos = new FileOutputStream("test");

fos.write(bytesArray);

fos.close();

string2int("cafebabe")

202.toHexString

"cafebabe".sliding(1, 1).toList.map(Integer.parseInt(_, 16)).map(_.toByte).map(_.toChar)

hex2string("ca")

string2hex("ca")

hex2string("cafebabe")

val appkey = "9GLV//lv/kYFW2o3/bihxwnMcmo="

        // string to hex

        val appkey_hex = string2hex(appkey)

        // 39474c562f2f6c762f6b594657326f332f62696878776e4d636d6f3d

        println(appkey_hex)

        // hex to string

        val appkey_string_again = hex2string(appkey_hex)

        // 9GLV//lv/kYFW2o3/bihxwnMcmo=

        println(appkey_string_again)

    }

List("ca", "fe", "ba", "be").map(_.toByte)

"ca".toByte