const crypto = require('crypto');

function buildSign(params, key) {
  const sortedKeys = Object.keys(params)
    .filter(k => k !== 'sign' && k !== 'sign_type' && params[k] !== '' && params[k] !== undefined)
    .sort();
  const queryStr = sortedKeys.map(k => k + '=' + params[k]).join('&');
  return crypto.createHash('md5').update(queryStr + key).digest('hex');
}

// 构造下单参数
const order = {
  pid: '1',
  type: 'alipay',
  out_trade_no: 'ORDER_' + Date.now(),
  notify_url: 'https://mysite.com/api/pay/notify',
  return_url: 'https://mysite.com/pay/success',
  name: '高级VIP会员月卡',
  money: '29.90',
};

const sign = buildSign(order, '您的32位商户密钥');
const payUrl = 'https://epay-pages.pages.dev/submit.php?' + new URLSearchParams({
  ...order,
  sign,
  sign_type: 'MD5'
}).toString();

console.log('请引导用户跳转此链接支付:', payUrl);

import hashlib
from urllib.parse import urlencode

def build_sign(params, key):
    filtered = sorted((k, v) for k, v in params.items() if k not in ('sign', 'sign_type') and v != '')
    query_str = '&'.join(f'{k}={v}' for k, v in filtered)
    return hashlib.md5((query_str + key).encode('utf-8')).hexdigest()

params = {
    'pid': '1',
    'type': 'wxpay',
    'out_trade_no': 'PY_1001',
    'notify_url': 'https://mysite.com/notify',
    'name': '赞助测试',
    'money': '5.00'
}
params['sign'] = build_sign(params, '商户密钥')
params['sign_type'] = 'MD5'
print('https://epay-pages.pages.dev/submit.php?' + urlencode(params))

<?php
$key = '您的商户密钥';
$params = $_GET;
$sign = $params['sign'];

// 排序并过滤空值与签名键
ksort($params);
$signParts = [];
foreach ($params as $k => $v) {
    if ($k !== 'sign' && $k !== 'sign_type' && $v !== '') {
        $signParts[] = "$k=$v";
    }
}
$expectSign = md5(implode('&', $signParts) . $key);

if ($sign === $expectSign) {
    if ($params['trade_status'] === 'TRADE_SUCCESS') {
        $tradeNo = $params['trade_no'];       // 平台订单号
        $outTradeNo = $params['out_trade_no']; // 商户订单号
        $money = $params['money'];             // 实付金额
        
        // 执行业务发货逻辑...
    }
    // 成功处理必须原样输出小写 success
    exit('success');
} else {
    exit('fail');
}

# 1. 订单状态查询 (GET)
GET /api.php?act=order&pid=商户ID&key=商户KEY&trade_no=平台订单号

# 2. 订单退款 (POST 表单)
POST /api.php?act=refundapi
trade_no=平台订单号&money=退款金额&key=md5(trade_no+系统KEY+trade_no)