本文介绍的是微信支付sdk+微擎，不是微擎原生支付

微信支付回调携带订单号，判断订单号获取uniacid

1、回调入口加session

//小程序支付回调
    public function receiveNotify()
    { 
        $notify = new WxNotify();
        $notify->Handle();
    }

2、配置文件加构造函数

创建订单和回调支付都会用到WxPayConfig.php
所以从回调入口加session，这里判断是否执行

//WxPayConfig.php
 public function __construct()
    {
        if(session('notify')){
            if(!session('wx_ucid')){
                return;
            }else{ 
                $uniacid=session('wx_ucid');
            }
        }else{ 
            $uniacid=TokenService::getCTVar('ucid');
            if(!$uniacid){
                $uniacid=TokenService::getCTVar('uniacid');
            }
            if(!$uniacid){
                throw new Exception("缺少标识");
            }
        }
        $xcx=SysConfig::where(['uniacid'=>$uniacid])->select();
        $arr=[];
        foreach ($xcx as $k=>$v){
            $arr[$v['key']]=$v['value'];
        }
        $this->APPID = $arr['wx_app_id'];
        $this->APPSECRET = $arr['wx_app_secret'];
        $this->MCHID = $arr['pay_num'];
        $this->KEY = $arr['pay_key'];
        $this->CURL_PROXY_HOST = "0.0.0.0";
        $this->CURL_PROXY_PORT = 0;
        $this->REPORT_LEVENL= 1;
        $this->SSLCERT_PATH = '/cert/apiclient_cert.pem';
        $this->SSLKEY_PATH = '/cert/apiclient_key.pem';
    }

3、获取uniacid

//WxPayData.php
 public function FromXml($xml)
    {
        if(!$xml){
            throw new WxPayException("xml数据异常！");
        }
        //将XML转为array
        //禁止引用外部xml实体
        libxml_disable_entity_loader(true);
        $this->values = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
        $order_num=$this->values['out_trade_no'];
        $uniacid=Order::where('order_num',$order_num)->value('uniacid');
        if($uniacid) {
            Log::error('ucid:'.$uniacid);
            session('wx_ucid', $uniacid);
        }
        return $this->values;
    }

4、更新订单状态

这里不需要修改

//自定义类继承NotifyProcess
public function NotifyProcess($data, &$msg){
  ...
}

5、回调结束告知微信服务器时，清空session

//WxPayNotify.php
final private function ReplyNotify($needSign = true)
    {
        //如果需要签名
        if($needSign == true && 
            $this->GetReturn_code() == "SUCCESS")
        {
            $this->SetSign();
        }
        session('notify',null);
        session('wx_ucid',null);
        WxpayApi::replyNotify($this->ToXml());
    }