微信退款（APP和公众号一样）

/**
 * 将xml转为array
 * @param  string   $xml xml字符串
 * @return array    转换得到的数组
 */
public function xml2array($xml)
{
    //禁止引用外部xml实体
    libxml_disable_entity_loader(false);
    $result = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
    return $result;
}

//用户退款
public  function postXmlCurl($xml, $url, $useCert = false, $second = 60, $oid = 0, $source)
{
    $ch = curl_init();
    //设置超时
    curl_setopt($ch, CURLOPT_TIMEOUT, $second);

    //如果有配置代理这里就设置代理
    if (
        WxPayConfig::CURL_PROXY_HOST != "0.0.0.0"
        && WxPayConfig::CURL_PROXY_PORT != 0
    ) {
        curl_setopt($ch, CURLOPT_PROXY, WxPayConfig::CURL_PROXY_HOST);
        curl_setopt($ch, CURLOPT_PROXYPORT, WxPayConfig::CURL_PROXY_PORT);
    }
    curl_setopt($ch, CURLOPT_URL, $url);
    // curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,FALSE);
    // curl_setopt($ch,CURLOPT_SSL_VERIFYHOST,FALSE);//严格校验
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, TRUE);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2); //严格校验
    //设置header
    curl_setopt($ch, CURLOPT_HEADER, FALSE);
    //要求结果为字符串且输出到屏幕上
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

    if ($useCert == true && $source == 2) {
        //设置证书
        //使用证书：cert 与 key 分别属于两个.pem文件
        curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'PEM');
        curl_setopt($ch, CURLOPT_SSLCERT, PayConfig::get_wx_config_info('sslcert_path', $oid));
        curl_setopt($ch, CURLOPT_SSLKEYTYPE, 'PEM');
        curl_setopt($ch, CURLOPT_SSLKEY, PayConfig::get_wx_config_info('sslkey_path', $oid));
    }elseif($useCert == true && $source == 5){

        curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'PEM');
        curl_setopt($ch, CURLOPT_SSLCERT, PayConfig::get_wx_config_info('wxGzhsslcert', $oid));
        curl_setopt($ch, CURLOPT_SSLKEYTYPE, 'PEM');
        curl_setopt($ch, CURLOPT_SSLKEY, PayConfig::get_wx_config_info('wxGzhsslkey', $oid));
    }

    //post提交方式
    curl_setopt($ch, CURLOPT_POST, TRUE);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
    //运行curl
    $data = curl_exec($ch);
    //返回结果
    if ($data) {
        curl_close($ch);
        return $data;
    } else {
        $error = curl_errno($ch);
        echo "call faild, errorCode:$error\n";
        curl_close($ch);
        return false;
    }
}

/**
 * 将一个数组转换为 XML 结构的字符串
 * @param array $arr 要转换的数组
 * @param int $level 节点层级, 1 为 Root.
 * @return string XML 结构的字符串
 */
public function array2xml($arr, $level = 1)
{
    $s = $level == 1 ? "<xml>" : '';
    foreach ($arr as $tagname => $value) {
        if (is_numeric($tagname)) {
            $tagname = $value['TagName'];
            unset($value['TagName']);
        }
        if (!is_array($value)) {
            $s .= "<{$tagname}>" . (!is_numeric($value) ? '<![CDATA[' : '') . $value . (!is_numeric($value) ? ']]>' : '') . "</{$tagname}>";
        } else {
            $s .= "<{$tagname}>" . $this->array2xml($value, $level + 1) . "</{$tagname}>";
        }
    }
    $s = preg_replace("/([\x01-\x08\x0b-\x0c\x0e-\x1f])+/", ' ', $s);
    return $level == 1 ? $s . "</xml>" : $s;
}

function wxrefund($order_id, $timeOut = 6)
{
    //$order_id = input('orsid');
    $order              = StoreOd::where('order_num', $order_id)->find();
    if (!$order) {
        return json(['code' => 2, 'data' => "", 'msg' => "无效订单号"]);
    }
    $refund_order       =  time() . rand(1000, 9999); //退款单号
    /*  $total_price    =  $order['price'] * 100;
        $refund_price       =  $order['price'] * 100; */
    $total_price        =  1;
    $refund_price       =  1;

    if ($order['source'] == 2){

        $merchid            = PayConfig::get_wx_config_info('wxmch_id', $order['oid']);
        $appid              = PayConfig::get_wx_config_info('wxappid', $order['oid']);
        $key                = PayConfig::get_wx_config_info('wxkey', $order['oid']);

    } elseif ($order['source'] == 5){

        $merchid            = PayConfig::get_wx_config_info('wxGzhMch_id', $order['oid']);
        $appid              = PayConfig::get_wx_config_info('wxGzhAppid', $order['oid']);
        $key                = PayConfig::get_wx_config_info('wxGzhKey', $order['oid']);
    }

    $nonce_str = '' . strval(mt_rand(100000, 999999)); //随机字符串
    $stra   = "appid=" . $appid . "&mch_id=" . $merchid . "&nonce_str=" . $nonce_str . "&op_user_id=" . $merchid . "&out_refund_no=" . $refund_order . "&out_trade_no=" . $order['order_num'] . "&refund_fee=" . $refund_price . "&total_fee=" . $total_price . "&key=" . $key;
    $sign   = strtoupper(md5($stra));

    $param  = [
        'appid'         => $appid,
        'mch_id'        => $merchid,
        'nonce_str'     => $nonce_str,
        'op_user_id'    => $merchid,
        'out_refund_no' => $refund_order, //商户退款单号
        'out_trade_no'  => $order['order_num'],
        'refund_fee'    => $refund_price, //退款金额
        'total_fee'     => $total_price,
        'sign'          => $sign
    ];
    $xmldata = self::array2xml($param);    //传入参数转换成xml格式
    $url     = "https://api.mch.weixin.qq.com/secapi/pay/refund";
    $res     = self::postXmlCurl($xmldata, $url, true, $timeOut, $order['oid'], $order['source']);   //curl发出请求

    if (!$res) {
        return ['status' => 1, 'msg' => "服务器连接失败"];
    }
    $content = self::xml2array($res);

    $data = ['out_refund_no' => $content['out_refund_no'], 'refund_id' => $content['refund_id'], 'refund_fee' => $content['refund_fee']];
    if ($content['result_code'] == 'SUCCESS') {
        return json(['code' => 1, 'data' => $data, 'msg' => '操作成功']);
    } else {
        return json(['code' => 2, 'data' => '', 'msg' => '操作失败,' . $content['err_code_des']]);
    }
}