How to implement Alipay's APP payment function in php (code)

 //支付宝
  include_once VENDOR_PATH . 'Alipay/aop/AopClient.php';
  include_once VENDOR_PATH . 'Alipay/aop/request/AlipayTradeAppPayRequest.php';
  $notify_url='https://www.www.com/app/pay/AlipayStep3Notify';
  $config = array(
   'appid' =>$this->appid,//
   'rsaPrivateKey' =>$this->rsaPrivateKey,//开发者私钥私钥
   'alipayrsaPublicKey'=>$this->alipayrsaPublicKey,//支付宝公钥
   'charset'=>strtolower('utf-8'),//编码
   'notify_url' =>$notify_url,//回调地址(支付宝支付成功后回调修改订单状态的地址)
   'payment_type' =>1,//(固定值)
   'seller_id' =>'',//收款商家账号
   'charset' => 'utf-8',//编码
   'sign_type' => 'RSA2',//签名方式
   'timestamp' =>date("Y-m-d H:i:s"),
   'version' =>"1.0",//固定值
   'url'  => 'https://openapi.alipay.com/gateway.do',//固定值
   'method' => 'alipay.trade.app.pay',//固定值
  );
   
     $aop = new \AopClient();
     $aop->gatewayUrl = "https://openapi.alipay.com/gateway.do";
     $aop->appId = $config['appid'];
     $aop->rsaPrivateKey = $config['rsaPrivateKey'];
     $aop->format = "json";
     $aop->charset = "UTF-8";
     $aop->signType = "RSA2";
     $aop->alipayrsaPublicKey=$config['alipayrsaPublicKey'];
    //实例化具体API对应的request类,类名称和接口名称对应,当前调用接口名称：alipay.trade.app.pay
     $request = new \AlipayTradeAppPayRequest();
    //SDK已经封装掉了公共参数，这里只需要传入业务参数
     
     $bizcontent = json_encode([
       'body'=>'**',
       'subject'=>$subject,
       'out_trade_no'=> $order_sn,//此订单号为商户唯一订单号
       'total_amount'=>$totalprice,//保留两位小数
       'product_code'=>'QUICK_MSECURITY_PAY'
     ]);
     $request->setNotifyUrl($config['notify_url']);
     $request->setBizContent($bizcontent);
    //这里和普通的接口调用不同，使用的是sdkExecute
     $response = $aop->sdkExecute($request);
    //htmlspecialchars是为了输出到页面时防止被浏览器将关键参数html转义，实际打印到日志以及http传输不会有这个问题
    $datas=$response;//就是orderString 可以直接给客户端请求，无需再做处理。
    $this->arr['code']=0;
    $this->arr['msg']=$order_sn;
    $this->arr['info']=$datas;
    echo json_encode($this->arr);exit;

include_once VENDOR_PATH . 'Alipay/aop/AopClient.php';
   $aop = new \AopClient();
   $config['alipayrsaPublicKey']=$this->$alipayrsaPublicKey;//公钥
   $aop->alipayrsaPublicKey = $config['alipayrsaPublicKey'];
   //此处验签方式必须与下单时的签名方式一致
   $flag = $aop->rsaCheckV1($_POST, NULL, "RSA2");
   //验签通过后再实现业务逻辑，比如修改订单表中的支付状态。
   /**
   ①验签通过后核实如下参数out_trade_no、total_amount、seller_id
   ②修改订单表
    **/
   $out_trade_no = I('post.out_trade_no'); //商户订单号

include_once VENDOR_PATH . 'Alipay/aop/SignData.php';
  include_once VENDOR_PATH . 'Alipay/aop/AopClient.php';
  include_once VENDOR_PATH . 'Alipay/aop/request/AlipayTradeQueryRequest.php';
  $config = array(
   'appid' =>$this->appid,//
   'rsaPrivateKey' =>$this->rsaPrivateKey,//开发者私钥私钥
   'alipayrsaPublicKey'=>$this->alipayrsaPublicKey,//支付宝公钥
   'charset'=>strtolower('utf-8'),//编码
   'notify_url' =>'',//回调地址(支付宝支付成功后回调修改订单状态的地址)
   'payment_type' =>1,//(固定值)
   'seller_id' =>'',//收款商家账号
   'charset' => 'utf-8',//编码
   'sign_type' => 'RSA',//签名方式
   'timestamp' =>date("Y-m-d H:i:s"),
   'version' =>"1.0",//固定值
   'url'  => 'https://openapi.alipay.com/gateway.do',//固定值
   'method' => 'alipay.trade.query',//固定值
  );
   
     $aop = new \AopClient();
     $aop->gatewayUrl = "https://openapi.alipay.com/gateway.do";
     $aop->appId = $config['appid'];
     $aop->rsaPrivateKey = $config['rsaPrivateKey'];
     $aop->format = "json";
     $aop->charset = "UTF-8";
     $aop->signType = "RSA2";
     $aop->method = $config['method'];
     $aop->apiVersion = '1.0';
     $aop->alipayrsaPublicKey=$config['alipayrsaPublicKey'];
    //实例化具体API对应的request类,类名称和接口名称对应,当前调用接口名称：alipay.trade.query
     $request = new \AlipayTradeQueryRequest();
 
     $bizcontent = json_encode([
       'out_trade_no'=>$order_sn,
       'trade_no'=>''
     ]);
     
     $request->setBizContent($bizcontent);
    
     $response = $aop->execute($request);
 
     $responseNode = str_replace(".", "_", $request->getApiMethodName()) . "_response";
     $resultCode = $response->$responseNode->code;
     if(!empty($resultCode)&&$resultCode == 10000){
  
       $this->arr['code']=0;
       $this->arr['msg']='success';
       echo json_encode($this->arr);exit;
    
     } else {
       $this->arr['code']=100001;
       $this->arr['msg']='未查询到订单信息';
        echo json_encode($this->arr);exit;
     
 }