微信支付退款流程 php

// 设置时区 

date_default_timezone_set("Asia/Shanghai");

// 配置

$ref = strtoupper(md5("appid=$appid&mch_id=$mch_id&nonce_str=$nonce_str&op_user_id=$user_id"
    . "&out_refund_no=$out_refund_no&out_trade_no=$transaction_id&refund_fee=$refund_fee&total_fee=$total_fee"
    . "&key=$key")); //sign加密MD5
$refund = ['appid' => $appid, //应用ID，固定
    'mch_id' => $mch_id, //商户号，固定
    'nonce_str' => $nonce_str, //随机字符串
    'op_user_id' => $user_id, //操作员
    'out_refund_no' => $out_refund_no, //商户内部唯一退款单号
    'out_trade_no' => $transaction_id, //商户订单号,pay_sn码 1.1二选一,微信生成的订单号，在支付通知中有返回
    //'transaction_id'=>$transaction_id,//微信订单号 1.2二选一,商户侧传给微信的订单号
    'refund_fee' => $refund_fee, //退款金额
    'total_fee' => $total_fee, //总金额
    'sign' => $ref//签名
];
微信签名认证工具 https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=20_1

$url = "https://api.mch.weixin.qq.com/secapi/pay/refund";
; //微信退款地址，post请求
$xml = arrayToXml($refund);
$ch = curl_init();
curl_setopt($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
// 设置证书
curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'pem');
curl_setopt($ch, CURLOPT_SSLCERT, $_SERVER['DOCUMENT_ROOT'] . '/plugins/payment/weixin/cert/apiclient_cert.pem');
curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'pem');
curl_setopt($ch, CURLOPT_SSLKEY, $_SERVER['DOCUMENT_ROOT'] . '/plugins/payment/weixin/cert/apiclient_key.pem');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
$xml = curl_exec($ch);
// 返回结果0的时候能只能表明程序是正常返回不一定说明退款成功而已
if ($xml) {
    curl_close($ch);
    // 把xml转化成数组
    libxml_disable_entity_loader(true);
    $xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);
    // var_dump($xmlstring);
    $result['errNum'] = 0;
    $result['info'] = (array)($xmlstring);
    return $result;
} else {
    $error = curl_errno($ch);
    curl_close($ch);
    // 错误的时候返回错误码。
    $result['errNum'] = $error;
    return $result;
}