code: public void bindService(final Runnable runnable) {
          if (isServiceConnected()) {
              runnable.run();
          } else {
              FileDownloadServiceProxy.getImpl().
                      bindStartByContext(FileDownloadHelper.getAppContext(), runnable);
          }
      }
docs: Start and bind the FileDownloader service and run {@code runnable} as soon as the binding is
  successful.
  <p>
  <strong>Tips:</strong> The FileDownloader service will start and bind automatically when any
  task is request to start.
  
  @param runnable the command will be executed as soon as the FileDownloader Service is
  successfully bound.
  @see #isServiceConnected()
  @see #bindService()
  @see #addServiceConnectListener(FileDownloadConnectListener)