小程序的支付功能实现

const crypto = require('crypto');
const axios = require('axios');
const xml2js = require('xml2js');

const generateNonceStr = () => Math.random().toString(36).substr(2, 15);

const createSign = (params, key) => {
  let stringA = Object.keys(params).sort().map(k => `${k}=${params[k]}`).join('&');
  let stringSignTemp = `${stringA}&key=${key}`;
  return crypto.createHash('md5').update(stringSignTemp, 'utf8').digest('hex').toUpperCase();
};

async function createOrder(openid, total_fee) {
  const appid = '你的小程序AppID';
  const mch_id = '你的商户号';
  const key = '你的API密钥';
  const notify_url = 'https://你的服务器地址/notify';
  const nonce_str = generateNonceStr();
  
  const orderParams = {
    appid,
    mch_id,
    nonce_str,
    body: '商品描述',
    out_trade_no: '订单号' + Date.now(),
    total_fee, // 单位：分
    spbill_create_ip: '用户IP',
    notify_url,
    trade_type: 'JSAPI',
    openid
  };
  
  orderParams.sign = createSign(orderParams, key);
  
  const builder = new xml2js.Builder({ rootName: 'xml', headless: true });
  const xmlData = builder.buildObject(orderParams);

  const response = await axios.post('https://api.mch.weixin.qq.com/pay/unifiedorder', xmlData, {
    headers: { 'Content-Type': 'text/xml' }
  });

  const parser = new xml2js.Parser({ explicitArray: false, ignoreAttrs: true });
  const result = await parser.parseStringPromise(response.data);
  return result.xml.prepay_id;
}

module.exports = createOrder;

wx.login({
  success(loginRes) {
    wx.request({
      url: 'https://你的服务器地址/createOrder',
      method: 'POST',
      data: { openid: loginRes.code, total_fee: 100 }, // 金额单位：分
      success(res) {
        const prepay_id = res.data.prepay_id;
        wx.requestPayment({
          timeStamp: String(Date.now()),
          nonceStr: res.data.nonce_str,
          package: `prepay_id=${prepay_id}`,
          signType: 'MD5',
          paySign: res.data.sign,
          success() {
            wx.showToast({ title: '支付成功', icon: 'success' });
          },
          fail(err) {
            console.error('支付失败:', err);
          }
        });
      }
    });
  }
});

const express = require('express');
const xml2js = require('xml2js');

const app = express();
app.use(express.text({ type: 'text/xml' }));

app.post('/notify', async (req, res) => {
  const parser = new xml2js.Parser({ explicitArray: false, ignoreAttrs: true });
  const result = await parser.parseStringPromise(req.body);

  if (result.xml.return_code === 'SUCCESS' && result.xml.result_code === 'SUCCESS') {
    console.log('支付成功:', result.xml);
    // 更新数据库订单状态
    res.send(`<xml><return_code><![CDATA[SUCCESS]]></return_code></xml>`);
  } else {
    console.error('支付失败:', result.xml);
    res.send(`<xml><return_code><![CDATA[FAIL]]></return_code></xml>`);
  }
});

app.listen(3000, () => console.log('服务器运行中'));