What is the best way to upload a directory in grails ?

I try this code :

  def upload = {
    if(request.method == 'POST') {
        Iterator itr = request.getFileNames();

        while(itr.hasNext()) {
            MultipartFile file = request.getFile(itr.next());
            File destination = new File(file.getOriginalFilename())

            if (!file.isEmpty()) {
                file.transferTo(destination)
                // success
            }
            else
            {
                // failure
            }
        }

        response.sendError(200,'Done');
    }
  }

Unfortunately, I can only upload file by file. I would like to define my directory, and upload all files directly.

Any ideas ?