code: public function initNotify($channel, array $config)
      {
          try {
              switch ($channel) {
                  case Config::ALI_CHARGE:
                      $this->notify = new AliNotify($config);
                      break;
                  case Config::WX_CHARGE:
                      $this->notify = new WxNotify($config);
                      break;
                  case Config::CMB_CHARGE:
                      $this->notify = new CmbNotify($config);
                      break;
                  default:
                      throw new PayException('当前仅支持：ALI_CHARGE WX_CHARGE CMB_CHARGE 常量');
              }
          } catch (PayException $e) {
              throw $e;
          }
      }
docs: 设置对应的通知渠道
  @param string $channel 通知渠道
  - @see Config
  
  @param array $config 配置文件
  @throws PayException
  @author helei