Kotlin中操作二进制数据

data class OPCodePacket(
    val op: Int,
    val body: String
) {
    fun toByteArray(): ByteArray {
        val bodySize = body.toByteArray().size
        val body = body.toByteArray()
        val totalLength = 4 + 4 + bodySize
        val buffer = ByteBuffer.allocate(totalLength).apply {
            putInt(op)
            putInt(bodySize)
            put(body)
        }
        return buffer.array()
    }

    companion object {
        fun fromByteArray(buffer: ByteBuffer): OPCodePacket {
            buffer.flip()
            val op = buffer.int
            val bodySize = buffer.int
            val body = ByteArray(bodySize).apply {
                buffer.get(this)
            }
            return OPCodePacket(op, String(body))
        }
    }
}