function arrayToXml($arr)
    {
        $xml = "<xml>";
        foreach ($arr as $key=>$val)
        {
            if (is_numeric($val)){
                $xml.="<".$key.">".$val."</".$key.">";
            }else{
                 $xml.="<".$key."><![CDATA[".$val."]]></".$key.">";
            }
        }
        $xml.="</xml>";
        return $xml;
    }

    function xmlToArray($xml)
    {    
        //禁止引用外部xml实体
        libxml_disable_entity_loader(true);
        $values = json_decode(json_encode(simplexml_load_string($xml, ‘SimpleXMLElement‘, LIBXML_NOCDATA)), true);        
        return $values;
    }

　　　　　　　$appid = C(‘APPID‘);  //appid
            $mch_id = C(‘MCH_ID‘); //商户号
            $key = C(‘KEY‘);  //商户秘钥key
            $nonce_str = md5(time().mt_rand(0,1000)); //随机字符串
            $total_fee = $order_list[‘goods_amount‘]*100; //订单金额
            $refund_fee = $order_list[‘goods_amount‘]*100; //退款金额

            $sign = md5("appid=$appid&mch_id=$mch_id&nonce_str=$nonce_str&out_refund_no=$out_refund_no&out_trade_no=$out_trade_no&refund_fee=$refund_fee&total_fee=$total_fee&key=$key");

            $array = array(
                ‘appid‘ => $appid,
                ‘mch_id‘ => $mch_id,
                ‘nonce_str‘ => $nonce_str,
                ‘out_refund_no‘ => $out_refund_no,
                ‘out_trade_no‘ => $out_trade_no,
                ‘refund_fee‘ => $refund_fee,
                ‘total_fee‘ => $total_fee,
                ‘sign‘ => $sign,
            );

            $url = ‘https://api.mch.weixin.qq.com/secapi/pay/refund‘;
            $xml = arrayToXml($array);

            $ch=curl_init();
            curl_setopt($ch,CURLOPT_URL,$url);
            // curl_setopt($ch,CURLOPT_HEADER,1);
            curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
            curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,1);//证书检查
            curl_setopt($ch,CURLOPT_SSLCERTTYPE,‘pem‘);
            curl_setopt($ch,CURLOPT_SSLCERT,dirname(dirname(dirname(__FILE__))).‘/cert/apiclient_cert.pem‘);
            curl_setopt($ch,CURLOPT_SSLCERTTYPE,‘pem‘);
            curl_setopt($ch,CURLOPT_SSLKEY,dirname(dirname(dirname(__FILE__))).‘/cert/apiclient_key.pem‘);
            curl_setopt($ch,CURLOPT_SSLCERTTYPE,‘pem‘);
            curl_setopt($ch,CURLOPT_CAINFO,dirname(dirname(dirname(__FILE__))).‘/cert/rootca.pem‘);
            curl_setopt($ch,CURLOPT_POST,1);
            curl_setopt($ch,CURLOPT_POSTFIELDS,$xml);

            
            $data=curl_exec($ch);
            $data = xmlToArray($data);
        }
        
        if($data[‘return_code‘] == ‘SUCCESS‘ && $data[‘result_code‘] == ‘SUCCESS‘){
        //返回来的是xml格式需要转换成数组再提取值，用来做更新
            curl_close($ch);
　　　　　}else{

　　　　　　　　$ajax[‘status‘] = ‘error‘;
　　　　　　　　$ajax[‘content‘] = $data[‘err_code_des‘];
　　　　　　　　curl_close($ch);
　　　　　　}