关于微信支付后回调验证的处理

参考来源：

废话不多说，直接上代码：

 public function demo()
    {
        // 获取微信回调的数据
        $notifiedData = file_get_contents(\'php://input\');

        //XML格式转换
        $xmlObj = simplexml_load_string($notifiedData, \'SimpleXMLElement\', LIBXML_NOCDATA);
        $xmlObj = json_decode(json_encode($xmlObj),true);
        
        $key = "公众号的key";

        //请求回来的数据格式
//        $xmlObj = [
//            \'appid\' => \'wxf546a8df41c2ce18\',
//            \'attach\' => \'商品\',
//            \'bank_type\' => \'CFT\',
//            \'cash_fee\' => \'1\',
//            \'fee_type\' => \'CNY\',
//            \'is_subscribe\' => \'Y\',
//            \'mch_id\' => \'1534940151\',
//            \'nonce_str\' => \'jld6md2ky75emve7spsrf2tolturngrm\',
//            \'openid\' => \'oyljP5y2HbOHsEAuOLpHP2dXQChw\',
//            \'out_trade_no\' => \'20190808164259728748651734197807\',
//            \'result_code\' => \'SUCCESS\',
//            \'return_code\' => \'SUCCESS\',
//            \'sign\' => \'A68DC8C8E61DCA90D4454963982A7B12\',
//            \'time_end\' => \'20190808164308\',
//            \'total_fee\' => \'1\',
//            \'trade_type\' => \'JSAPI\',
//            \'transaction_id\' => \'4200000342201908088760422065\',
//        ];
        

        //是否成功支付
        if ($xmlObj[\'return_code\'] == "SUCCESS" && $xmlObj[\'result_code\'] == "SUCCESS") {

            //把签名去掉
            $xmlSign = $xmlObj[\'sign\'];
            unset($xmlObj[\'sign\']);


            $sign = $this -> appgetSign($xmlObj,$key);

            if ($sign === $xmlSign)
            {
                //验证通过，确认已经支付

                //告诉微信不用重复通知
                return "<xml><return_code><![CDATA[SUCCESS]]></return_code><return_msg><![CDATA[OK]]></return_msg></xml>";

            }
            
        }
    }


    /*
     * 格式化参数格式化成url参数  生成签名sign
     */
    private function appgetSign($Obj,$appwxpay_key)
    {

        foreach ($Obj as $k => $v)
        {
            $Parameters[$k] = $v;
        }


        //签名步骤一：按字典序排序参数
        ksort($Parameters);
        $String = $this -> ToUrlParams($Parameters);


        //签名步骤二：在string后加入KEY

        if($appwxpay_key){
            $String = $String."&key=".$appwxpay_key;
        }


        //签名步骤三：MD5加密
        $String = md5($String);



        //签名步骤四：所有字符转为大写
        $result_ = strtoupper($String);


        return $result_;
    }


    private function ToUrlParams($Parameters)
    {
        $buff = "";
        foreach ($Parameters as $k => $v)
        {
            if($k != "sign" && $v != "" && !is_array($v)){
                $buff .= $k . "=" . $v . "&";
            }
        }

        $buff = trim($buff, "&");
        return $buff;
    }