这是支付宝已经封装好的类:

/** rsaCheckV1 & rsaCheckV2
  * 验证签名
  * 在使用本方法前，必须初始化AopClient且传入公钥参数。
  * 公钥是否是读取字符串还是读取文件，是根据初始化传入的值判断的。
  **/
 public function rsaCheckV1($params, $rsaPublicKeyFilePath,$signType='RSA') {
  $sign = $params['sign'];
  $params['sign_type'] = null;
  $params['sign'] = null;
  $this->alipayrsaPublicKey = $rsaPublicKeyFilePath;
 
  return $this->verify($this->getSignContent($params), $sign, $rsaPublicKeyFilePath,$signType);
 }
 public function rsaCheckV2($params, $rsaPublicKeyFilePath, $signType='RSA') {
  $sign = $params['sign'];
  $params['sign'] = null;
  return $this->verify($this->getSignContent($params), $sign, $rsaPublicKeyFilePath, $signType);
 }
 function verify($data, $sign, $rsaPublicKeyFilePath, $signType = 'RSA') {
 
  if($this->checkEmpty($this->alipayPublicKey)){
 
   $pubKey= $this->alipayrsaPublicKey;
   $res = "-----BEGIN PUBLIC KEY-----\n" .
    wordwrap($pubKey, 64, "\n", true) .
    "\n-----END PUBLIC KEY-----";
  }else {
   //读取公钥文件
   $pubKey = file_get_contents($rsaPublicKeyFilePath);
   //转换为openssl格式密钥
   $res = openssl_get_publickey($pubKey);
  }
 
  ($res) or die('支付宝RSA公钥错误。请检查公钥文件格式是否正确'); 
 
  //调用openssl内置方法验签，返回bool值
  if ("RSA2" == $signType) {
   $result = (bool)openssl_verify($data, base64_decode($sign), $res, OPENSSL_ALGO_SHA256);
  } else {
   $result = (bool)openssl_verify($data, base64_decode($sign), $res);
  }
 
  if(!$this->checkEmpty($this->alipayPublicKey)) {
   //释放资源
   openssl_free_key($res);
  }
 
  return $result;
 }

支付宝的回调参数是以post的方式回传的,但是我们在测试的时候可以直接把回调url直接写在地址栏里面,然后用get方式接受,这样就不用拼参数了,结果是一样的(回调url可以记录在log文件里面),还有就是验签的时候需要所有的回传参数原封不动的去验签,而这里自己需要什么参数就接收什么参数就可以,这里就不多说了,就是正常的接受参数的问题.下面给出我在验证参数时,检验订单金额和商家编号的代码,仅做参考(我用的tp5):

public function check($receipt_amount,$buyer_pay_amount,$order_price,$app_id,$seller_email){
  if($receipt_amount !== $order_price || $buyer_pay_amount !== $order_price){
//    echo 1;
   return $this->log('订单支付金额有误!');
  }
  //支付宝支付的所有参数
  $alipay_config = Config::get('alipay_config');
  if($app_id !== $alipay_config['appid']){
//   echo 2;
    return $this->log('商家编号有误!');
  }
 
  //验证收款商家是否正确
  if($seller_email !== $alipay_config['seller_id']){
//   echo 3;
   return $this->log('收款商家有误!');
  }
  return 'success';
 }

这里主要就是检验库存,这里最好用事物处理,(虽然你的订单量可能不一定回到这个地步),下面给出我的代码,仅做参考(tp5):

public function index($order_sn='')
 {
  if(isset($_POST['order_sn']) && empty($order_sn)){
   $order_sn = $_POST['order_sn'];
  }
 
  $table = self::order_info($order_sn);
  if($table == 'failure'){return 'false';}
  $oid = $table['order_id'];
  //通过订单id $oid 查询出订单中物品的id
  $goodsTable = Db::name('goods');
  $allgoods = Db::name("test1")->where('o_id', $oid)->field('g_id,g_num')->select();
  foreach ($allgoods as $k => $v) {
   //事务处理
   $goodsTable->startTrans();//事物开始
   try {
    //判断库存数量
    $goodsTable->query('update test2 set g_num = g_num-' . $v['g_num'] . ' where g_num >= ' . $v['g_num'] . ' and gid =' . $v['g_id']);
 
   } catch (\Exception $e) {
    $goodsTable->rollBack();//事物回滚
   }
 
   $goodsTable->commit();// 事物提交
  }
 
  //修改订单
  $res = Db::name('test3')->where('order_sn',$order_sn)->update(['order_state' => '1','pay_time'=>time()]);
  if($res != 0){
   return 'success';
  }
 }