code: public function initHelper($way, array $config)
      {
          try {
              switch ($way) {
                  case Config::CMB_BIND:
                      $this->helper = new BindCardHelper($config);
                      break;
                  case Config::CMB_PUB_KEY:
                      $this->helper = new PubKeyHelper($config);
                      break;
                  default:
                      throw new PayException('当前仅支持：CMB_BIND CMB_PUB_KEY 操作');
              }
          } catch (PayException $e) {
              throw $e;
          }
      }
docs: 设置对应的退款渠道
  @param string $way 对应的方式渠道
  - @see Config
  
  @param array $config 配置文件
  @throws PayException
  @author helei