import('alipay.AopClient', EXTEND_PATH);
import('alipay.request.AlipayTradeAppPayRequest', EXTEND_PATH);
$aop = new \AopClient();
$aop->gatewayUrl = "https://openapi.alipay.com/gateway.do";
$aop->appId = Config::get('alipay.app_id');
$aop->rsaPrivateKey = Config::get('alipay.rsa_private_key');
$aop->format = "json";
$aop->charset = "UTF-8";
$aop->signType = "RSA2";
$aop->alipayrsaPublicKey = Config::get('alipay.alipay_rsa_public_key'); //Config::get('alipay.rsa_public_key'); //
$request = new \AlipayTradeAppPayRequest();
$bizcontent = json_encode([
  'body' => '紅包支付',
  'subject' => '用戶紅包支付',
  'out_trade_no' => $orderSn,
  'timeout_express' => '30m',
  'total_amount' => $amount,
  'product_code' => 'QUICK_MSECURITY_PAY'
]);
$request->setNotifyUrl("https://" . $_SERVER['HTTP_HOST'] . "/api/callback/alipay");
$request->setBizContent($bizcontent);//這里和普通的接口調用不同，使用的是sdkExecute
$response = $aop->sdkExecute($request);
$return['aliresponse'] = $response;//htmlspecialchars($response);//htmlspecialchars是為了輸出到頁面時防止被瀏覽器將關鍵參數html轉義，實際打印到日志以及http傳輸不會有這個問題
$this->returnSuccess($return);

public function alipay()
{
    import('alipay.AopClient', EXTEND_PATH);
    $aop = new \AopClient();
    $aop->alipayrsaPublicKey = Config::get('alipay.alipay_rsa_public_key');// file_get_contents($_SERVER['DOCUMENT_ROOT']."/key/alipay/alipay_public_key.txt");
    $flag = $aop->rsaCheckV1($_POST, NULL, "RSA2");
    if ($flag){
      //驗簽通過后核實如下參數trade_status、out_trade_no、total_amount、seller_id
      if (isset($_POST['trade_status'])  ($_POST['trade_status'] == 'TRADE_SUCCESS' || $_POST['trade_status'] == 'TRADE_FINISHED') ) {
        // 業務處理
      } else {
        $msg = var_export($_POST, true);
        $fileName = mt_rand(10,1000) .'00alisuccessAnother.log' ;
        file_put_contents($fileName, $msg);
      }
      echo "success";
    } else {
      $msg = var_export($_POST, true);
      $fileName = mt_rand(10,1000) .'00alicheckSignFail.log';
      file_put_contents($fileName, $msg);
    }
}

eg:
echo "success";

echo "xml>return_code>![CDATA[SUCCESS]]>/return_code>return_msg>![CDATA[OK]]>/return_msg>/xml>"; 

echo exit('xml>return_code>![CDATA[SUCCESS]]>/return_code>return_msg>![CDATA[OK]]>/return_msg>/xml>');