NettyUtil.scala

import io.netty.buffer.{Unpooled, ByteBuf}
import java.nio.charset.Charset

object NettyUtil {

  implicit class ByteBufOps(val buf: ByteBuf) extends AnyVal {

    def getUTF(index: Int): String = {
      val length = buf.getUnsignedShort(index)
      sliceToString(index + 2, length)
    }

    def readUTF(): String = {
      val length = buf.getUnsignedShort(buf.readerIndex())
      val s = sliceToString(buf.readerIndex() + 2, length)
      buf.skipBytes(length + 2)
      s
    }

    private def sliceToString(index: Int, length: Int): String =
      buf.slice(index, length).toString(Charset.forName("UTF8"))


    def setUTF(index: Int, s: String): ByteBuf = {
      set(index, s)
      buf
    }

    def writeUTF(s: String): ByteBuf = {
      val length = set(buf.writerIndex(), s)
      buf.writerIndex(buf.writerIndex() + length + 2)
    }

    private def set(index: Int, s: String): Int = {
      val sb = Unpooled.copiedBuffer(s, Charset.forName("UTF8"))
      val length = sb.readableBytes()
      buf.setBytes(index + 2, sb)
      buf.setShort(index, length)
      length
    }

  }

}