refreshServerUrlByRouter = function refreshServerUrlByRouter() {
  var url = 'https://app-router.leancloud.cn/1/route?appId=' + AV.applicationId;
  return ajax('get', url).then(function (servers) {
    if (servers.api_server) {
      setServerUrl(servers.api_server);
      return cacheServerURL(servers.api_server, servers.ttl);
    }
  }, function (error) {
    // bypass all non-4XX errors
    if (error.statusCode >= 400 && error.statusCode < 500) {
      throw error;
    }
  });
}
When API request need to redirect to the right location,
      can't use browser redirect by http status 307, as the reason of CORS,
      so API server response http status 410 and the param "location" for this case.