Extracter

gistfile1.java

public abstract class Extracter {
  public void extract(HttpServletRequest request) throws FileUploadException, IOException {
    ServletFileUpload upload = new ServletFileUpload();

    FileItemIterator iterator = upload.getItemIterator(request);

    while (iterator.hasNext()) {
      FileItemStream item = iterator.next();

      if (!item.isFormField()) {
        byte[] content = extractContent(item);
        String contentType = item.getContentType();

        workOnItem(content, contentType);
      }
    }  
  }

  public abstract void workOnItem(byte[] content, String contentType) throws IOException;
  
  private byte[] extractContent(FileItemStream item) throws IOException {
    InputStream stream = item.openStream();
    ByteBuffer content = ByteBuffer.wrap(IOUtils.toByteArray(stream));
    byte[] bytes = content.array();

    IOUtils.closeQuietly(stream);

    return bytes;
  }  
}

  private class MyExtracter extends Extracter {
    @Override
    public void workOnItem(byte[] content, String contentType) throws IOException {
      BlobKey hd = generateHd(content, contentType);
      BlobKey midSize = generateMidSize(content, contentType);
      BlobKey thumbnail = generateThumbnail(content, contentType);

      createPicture(hd, midSize, thumbnail);     
    }
  }