code: public function getAccessToken($code)
      {
          $params = [
              'client_id'     => $this->appKey,
              'client_secret' => $this->appSecret,
              'grant_type'    => $this->grantType,
              'redirect_uri'  => $this->callback,
              'code'          => $code,
          ];
          // 获取token信息
          $data = $this->http($this->getAccessTokenURL, $params, 'POST');
          // 解析token
          $this->token = $this->parseToken($data);
          return $this->token;
      }
docs: 获取access_token
  @param string $code 授权登录成功后得到的code信息