thinkphp5.0 中简单处理微信支付异步通知

public function wx_notify(){
        $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
        libxml_disable_entity_loader(true);
        $xml = json_decode(json_encode(simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA)), true);        
        if($xml['out_trade_no']){
            $rs = Db::name('order_jiaoche')->where(array('order_sn'=>$xml['out_trade_no']))->find();
            if($rs){
                Db::name('order_jiaoche')->where(array('order_sn'=>$xml['out_trade_no']))->update(array('ispay'=>1));
                echo 'success';
            }
        }        
         /*
         调试所用 
         $fp = fopen('notify.txt','a+'); 
         fwrite($fp,"
 _______GET________");   
         fwrite($fp,var_export($xml,true));     
         fwrite($fp,"
 ________postObj________");
         fwrite($fp,var_export($xml,true));
         fwrite($fp,'【 Now 】:  '. date("Y-m-d H:i:s") ."
");
         fclose($fp); 
         print_r($xml);
         */
    }