First there is a snippet using the bind functionality.
var image : FileParamHolder = _

bind("widget", xhtml,
  "image" -> fileUpload(image = _)

}

Now write out:

val wbos : ByteArrayOutputStream = build(image)
val fout = new File(outputFilename)
if (fout.exists()) {
   Log.error("Tried to overwrite existing file")
   return "Error: Filename already exists"
}

val foStream = new FileOutputStream(fout)
foStream.write(wbos.toByteArray())
foStream.close()

def build(image : FileParamHolder) : ByteArrayOutputStream = {
  val bout = new ByteArrayOutputStream()
  val zipout : ZipOutputStream = new ZipOutputStream(bout)
  zipout.setMethod(ZipOutputStream.DEFLATED);
  zipout.setLevel(Deflater.DEFAULT_COMPRESSION);

  writeImage(zos, image)

}

private def writeImage(zos: ZipOutputStream,
image:FileParamHolder):Unit = {
    if (image.fileName == "") {
      Log.info("Provided image file is null")
      return
    }
    if (image.fileName.lastIndexOf("\\") != -1) //this is needed if
upload is from a windows system
      zos.putNextEntry(new ZipEntry("res/" + image.fileName.substring
(image.fileName.lastIndexOf("\\")+1)))
    else
      zos.putNextEntry(new ZipEntry("res/" + image.fileName))
    zos.write(image.file, 0, image.file.length) //make here a loop on
very large files
    zos.closeEntry()

}