read bytes from java.io.InputStream and process them by closure

gistfile1.scala

processInputStream(new java.io.FileInputStream("test.jpg"), 8 * 1024){ bytes =>
  ...
}

/**
 * Invokes the given function for each read bytes with specified size from java.io.InputStream.
 */
@tailrec
def processInputStream(in: java.io.InputStream, bufferSize: Int)(func: Array[Byte] => Unit): Unit = {
  val buffer = new Array[Byte](bufferSize)
  in.read(buffer) match {
    case -1  => 
    case len => func(buffer.slice(0, len)); processInputStream(in, bufferSize)(func)
  }
}