messaging.py 文件源码

def _get_access_token():
  """Retrieve a valid access token that can be used to authorize requests.

  :return: Access token.
  """
  credentials = ServiceAccountCredentials.from_json_keyfile_name(
      'service-account.json', FCM_SCOPE)
  access_token_info = credentials.get_access_token()
  return access_token_info.access_token
# [END retrieve_access_token]