[JAVA] HMAC in Kotlin

Note how to encrypt with HMAC in Kotlin. Other various encryptions in Kotlin are [phxql / kotin-crypto-example](https://github.com/phxql/kotlin-crypto-example/blob/ There is a sample in master / src / main / kotlin / de / mkammerer / Crypto.kt).

import javax.crypto.Mac
import javax.crypto.spec.SecretKeySpec
import kotlin.experimental.and

/**
 * Hmac by Kotlin
 */
fun main(args: Array<String>) {

    // Change algorithm as you like. ex. "HmacSHA1", "HmacMD5", etc
    val algorithm = "HmacSHA256"
    val key = "Secret Key"
    val text = "Encryption Target"

    // Encryption
    val keySpec = SecretKeySpec(key.toByteArray(), algorithm)
    val mac = Mac.getInstance(algorithm)
    mac.init(keySpec)
    val sign = mac.doFinal(text.toByteArray())
            .joinToString("") { String.format("%02x", it and 255.toByte()) }

    // 6bad2e332a94882be27d946b5fab39acd6be6fd64c6a52a27d77422daf36a6fd
    println(sign)
}