public GoogleDriveDownloadTask(String fileName) {
   if (DriveUtil.service == null) {
     try {
       DriveUtil.getDriveService();
     } catch (GeneralSecurityException | IOException | URISyntaxException e) {
       MAMUtil.writeLog(e);
       e.printStackTrace();
     }
   }
   ArrayList<String> fileList = new ArrayList<String>();
   fileList.add(fileName);
   this.fileList = fileList;
   this.totalFileNumber = 1;
 }
  private InputStream downloadFile(String fileName) throws IOException {
    File file = DriveUtil.getFileByName(fileName);

    if (file.getDownloadUrl() != null && file.getDownloadUrl().length() > 0)
      try {
        fileSize = file.getFileSize();
        return DriveUtil.service.files().get(file.getId()).executeMediaAsInputStream();
      } catch (IOException e) {
        e.printStackTrace();
        MAMUtil.writeLog(e);
        return null;
      }

    return null;
  }