<?php
header('Content-type:text/html; Charset=utf-8');
$mchid = 'xxxxx';   //微信支付商户号 PartnerID 通过微信支付商户资料审核后邮件发送
$appid = 'xxxxx';  //微信支付申请对应的公众号的APPID
$apiKey = 'xxxxx'; //https://pay.weixin.qq.com 帐户设置-安全设置-API安全-API密钥-设置API密钥
//以下四个单号四选一。查询的优先级是： 微信退款单号 > 商户退款订单号 > 微信订单号 > 商户订单号
$orderNo = '';                  //商户订单号
$wxOrderNo = '';                //微信订单号
$refundNo='';                   //商户退款订单号
$refundId = '';                 //微信退款单号（微信生成的退款单号，在申请退款接口有返回）
$wxPay = new WxpayService($mchid,$appid,$apiKey);
$result = $wxPay->doRefundQuery($refundNo, $wxOrderNo,$orderNo,$refundId);
if($result===true){
    echo 'refund success';exit();
}
echo 'refund fail';
class WxpayService
{
    protected $mchid;
    protected $appid;
    protected $apiKey;
    public $data = null;
    public function __construct($mchid, $appid, $key)
    {
        $this->mchid = $mchid; //https://pay.weixin.qq.com 产品中心-开发配置-商户号
        $this->appid = $appid; //微信支付申请对应的公众号的APPID
        $this->apiKey = $key;   //https://pay.weixin.qq.com 帐户设置-安全设置-API安全-API密钥-设置API密钥
    }
    /**
     * 退款查询
     * @param string $refundNo 商户退款单号
     * @param string $wxOrderNo 微信订单号
     * @param string $orderNo 商户订单号
     * @param string $refundId 微信退款单号
     * @return string
     */
    public function doRefundQuery($refundNo='', $wxOrderNo='',$orderNo='',$refundId='')
    {
        $config = array(
            'mch_id' => $this->mchid,
            'appid' => $this->appid,
            'key' => $this->apiKey,
        );
        $unified = array(
            'appid' => $config['appid'],
            'mch_id' => $config['mch_id'],
            'nonce_str' => self::createNonceStr(),
            'sign_type' => 'MD5',           //签名类型 支持HMAC-SHA256和MD5，默认为MD5
            'transaction_id'=>$wxOrderNo,               //微信订单号
            'out_trade_no'=>$orderNo,        //商户订单号
            'out_refund_no'=>$refundNo,        //商户退款单号
            'refund_id'=>$refundId,     //微信退款单号
        );
        $unified['sign'] = self::getSign($unified, $config['key']);
        $responseXml = $this->curlPost('https://api.mch.weixin.qq.com/pay/refundquery', self::arrayToXml($unified));
        file_put_contents('2.txt',$responseXml);
        $unifiedOrder = simplexml_load_string($responseXml, 'SimpleXMLElement', LIBXML_NOCDATA);
        if ($unifiedOrder === false) {
            die('parse xml error');
        }
        if ($unifiedOrder->return_code != 'SUCCESS') {
            die($unifiedOrder->return_msg);
        }
        if ($unifiedOrder->result_code != 'SUCCESS') {
            die($unifiedOrder->err_code);
        }
        return true;
    }
    public static function curlGet($url = '', $options = array())
    {
        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_TIMEOUT, 30);
        if (!empty($options)) {
            curl_setopt_array($ch, $options);
        }
        //https请求 不验证证书和host
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        $data = curl_exec($ch);
        curl_close($ch);
        return $data;
    }
    public function curlPost($url = '', $postData = '', $options = array())
    {
        if (is_array($postData)) {
            $postData = http_build_query($postData);
        }
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
        curl_setopt($ch, CURLOPT_TIMEOUT, 30); //设置cURL允许执行的最长秒数
        if (!empty($options)) {
            curl_setopt_array($ch, $options);
        }
        //https请求 不验证证书和host
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        $data = curl_exec($ch);
        curl_close($ch);
        return $data;
    }
    public static function createNonceStr($length = 16)
    {
        $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
        $str = '';
        for ($i = 0; $i < $length; $i++) {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
    }
    public static function arrayToXml($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 $xml;
    }
    public static function getSign($params, $key)
    {
        ksort($params, SORT_STRING);
        $unSignParaString = self::formatQueryParaMap($params, false);
        $signStr = strtoupper(md5($unSignParaString . "&key=" . $key));
        return $signStr;
    }
    protected static function formatQueryParaMap($paraMap, $urlEncode = false)
    {
        $buff = "";
        ksort($paraMap);
        foreach ($paraMap as $k => $v) {
            if (null != $v && "null" != $v) {
                if ($urlEncode) {
                    $v = urlencode($v);
                }
                $buff .= $k . "=" . $v . "&";
            }
        }
        $reqPar = '';
        if (strlen($buff) > 0) {
            $reqPar = substr($buff, 0, strlen($buff) - 1);
        }
        return $reqPar;
    }
}
?>