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KEYif($appwxpay_key){$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;}