code: function getService(params, callback) {
      if (typeof params === 'function') {
          callback = params;
          params = {};
      }
      var protocol = this.options.Protocol || (util.isBrowser && location.protocol === 'http:' ? 'http:' : 'https:');
      var domain = this.options.ServiceDomain;
      var appId = params.AppId || this.options.appId;
      if (domain) {
          domain = domain.replace(/\{\{AppId\}\}/ig, appId || '').replace(/\{\{.*?\}\}/ig, '');
          if (!/^[a-zA-Z]+:\/\//.test(domain)) {
              domain = protocol + '//' + domain;
          }
          if (domain.slice(-1) === '/') {
              domain = domain.slice(0, -1);
          }
      } else {
          domain = protocol + '//service.cos.myqcloud.com';
      }
      submitRequest.call(this, {
          Action: 'name/cos:GetService',
          url: domain,
          method: 'GET',
          headers: params.Headers,
      }, function (err, data) {
          if (err) {
              return callback(err);
          }
          var buckets = (data && data.ListAllMyBucketsResult && data.ListAllMyBucketsResult.Buckets
              && data.ListAllMyBucketsResult.Buckets.Bucket) || [];
          buckets = util.isArray(buckets) ? buckets : [buckets];
          callback(null, {
              Buckets: buckets,
              statusCode: data.statusCode,
              headers: data.headers,
          });
      });
  }
docs: Bucket 相关 
  获取用户的 bucket 列表
  @param  {Object}  params         回调函数，必须，下面为参数列表
  无特殊参数
  @param  {Function}  callback     回调函数，必须