你自己的收款码，
扫码自动回调

// Xarr 码支付 · 统一下单（Java）
import java.security.MessageDigest;
import java.util.*;

public class XarrPay {
    public static void main(String[] args) throws Exception {
        TreeMap<String, String> p = new TreeMap<>();
        p.put("pid", "10001");
        p.put("type", "alipay");
        p.put("out_trade_no", "ORDER_" + System.currentTimeMillis());
        p.put("notify_url", "https://your.site/notify");
        p.put("name", "会员充值");
        p.put("money", "1.00");

        StringBuilder sb = new StringBuilder();
        p.forEach((k, v) -> sb.append(k).append("=").append(v).append("&"));
        sb.setLength(sb.length() - 1);

        p.put("sign", md5(sb + "YOUR_KEY"));
        p.put("sign_type", "MD5");
        System.out.println("https://api.xarr.pay/submit.php?" + toQuery(p));
    }

    static String md5(String s) throws Exception {
        byte[] d = MessageDigest.getInstance("MD5").digest(s.getBytes("UTF-8"));
        StringBuilder r = new StringBuilder();
        for (byte b : d) r.append(String.format("%02x", b));
        return r.toString();
    }
    static String toQuery(Map<String, String> m) { /* URLEncoder 拼接 */ return ""; }
}

# Xarr 码支付 · 统一下单（Python 3）
import hashlib, time, urllib.parse, requests

params = {
    "pid": "10001",
    "type": "wxpay",                # wxpay | alipay | qqpay
    "out_trade_no": "ORDER_" + str(int(time.time())),
    "notify_url": "https://your.site/notify",
    "return_url": "https://your.site/return",
    "name": "会员充值",
    "money": "1.00",
}

sign_src = "&".join(k + "=" + str(v) for k, v in sorted(params.items()))
params["sign"] = hashlib.md5((sign_src + "YOUR_KEY").encode()).hexdigest()
params["sign_type"] = "MD5"

url = "https://api.xarr.pay/submit.php?" + urllib.parse.urlencode(params)
print(requests.get(url).url)   # 返回收银台地址

// Xarr 码支付 · 统一下单（Go）
package main

import (
    "crypto/md5"
    "encoding/hex"
    "fmt"
    "net/url"
    "sort"
    "strings"
    "time"
)

func main() {
    p := map[string]string{
        "pid":          "10001",
        "type":         "wxpay",
        "out_trade_no": fmt.Sprintf("ORDER_%d", time.Now().Unix()),
        "notify_url":   "https://your.site/notify",
        "name":         "会员充值",
        "money":        "1.00",
    }
    keys := make([]string, 0, len(p))
    for k := range p { keys = append(keys, k) }
    sort.Strings(keys)

    var sb strings.Builder
    for i, k := range keys {
        if i > 0 { sb.WriteString("&") }
        sb.WriteString(k + "=" + p[k])
    }
    sum := md5.Sum([]byte(sb.String() + "YOUR_KEY"))
    p["sign"] = hex.EncodeToString(sum[:])
    p["sign_type"] = "MD5"

    q := url.Values{}
    for k, v := range p { q.Set(k, v) }
    fmt.Println("https://api.xarr.pay/submit.php?" + q.Encode())
}

// Xarr 码支付 · 统一下单（Node.js 18+）
import crypto from 'node:crypto';

const params = {
  pid: '10001',
  type: 'alipay',
  out_trade_no: 'ORDER_' + Date.now(),
  notify_url: 'https://your.site/notify',
  return_url: 'https://your.site/return',
  name: '会员充值',
  money: '1.00',
};

const src = Object.keys(params).sort()
  .map(k => k + '=' + params[k]).join('&');

params.sign = crypto.createHash('md5').update(src + 'YOUR_KEY').digest('hex');
params.sign_type = 'MD5';

const url = 'https://api.xarr.pay/submit.php?' + new URLSearchParams(params);
console.log(url);   // 展示收款码页面地址

// 异步回调验签（PHP）—— 务必校验签名并返回 success
<?php
$data = $_POST ?: $_GET;
$sign = $data['sign'];
unset($data['sign'], $data['sign_type']);

ksort($data);
if (md5(urldecode(http_build_query($data)) . 'YOUR_KEY') !== $sign) {
    exit('sign error');
}
if ($data['trade_status'] === 'TRADE_SUCCESS') {
    // 1. 校验订单金额与本地一致  2. 幂等处理，防重复发货
    // handleOrder($data['out_trade_no'], $data['money']);
}
echo 'success';   // 返回其他内容将触发重试