client.py 文件源码

def from_stream(credential_filename):
    """Create a Credentials object by reading the information from a given file.

    It returns an object of type GoogleCredentials.

    Args:
      credential_filename: the path to the file from where the credentials
        are to be read

    Exceptions:
      ApplicationDefaultCredentialsError: raised when the credentials fail
                                          to be retrieved.
    """

    if credential_filename and os.path.isfile(credential_filename):
      try:
        return _get_application_default_credential_from_file(
            credential_filename)
      except (ApplicationDefaultCredentialsError, ValueError) as error:
        extra_help = ' (provided as parameter to the from_stream() method)'
        _raise_exception_for_reading_json(credential_filename,
                                          extra_help,
                                          error)
    else:
      raise ApplicationDefaultCredentialsError(
          'The parameter passed to the from_stream() '
          'method should point to a file.')