微信小程序支付功能的实现

article/2025/10/15 5:54:40

前言

最近需要在微信小程序中用到在线支付功能，于是看了一下官方的文档，发现要在小程序里实现微信支付还是很方便的，如果你以前开发过服务号下的微信支付，那么你会发现其实小程序里的微信支付和服务号里的开发过程如出一辙，下面我就具体说一下小程序里微信支付的开发流程和注意点。

开始

第一步：开通微信支付和微信商户号

在这里插入图片描述

第二步，获得用户的openid

首页我们需要在小程序的客户端js中获取当前用户的openid,通过调用wx.login方法可以得到用户的code.

wx.login({success: function(res) {if (res.code) {//发起网络请求wx.request({url: 'https://yourwebsit/onLogin',method: 'POST',data: {code: res.code},success: function(res) {var openid = res.data.openid;},fail: function(err) {console.log(err)}})} else {console.log('获取用户登录态失败！' + res.errMsg)}}});

然后开发者服务器使用登录凭证 code 获取 openid。

var code = req.param("code");request({url: "https://api.weixin.qq.com/sns/jscode2session?appid="+appid+"&secret="+secret+"&js_code="+code+"&grant_type=authorization_code",method: 'GET'}, function(err, response, body) {if (!err && response.statusCode == 200) {res.json(JSON.parse(body));}});

第三步：获取prepay_id和支付签名验证paySign

这一步的过程就和服务号里的微信支付过程一样，分为客户端和服务器端

首先来看一下客户端js

在服务号里，我们是通过如下的代码来调起支付功能

function jsApiCall(){WeixinJSBridge.invoke('getBrandWCPayRequest',{"appId":"",   //公众号名称，由商户传入   "timeStamp":"",     //时间戳，自1970年以来的秒数   "nonceStr":"", //随机串   "package":"prepay_id=<%=prepay_id%>",   "signType":"MD5",     //微信签名方式：   "paySign":"<%=_paySignjs%>" //微信签名},function(res){WeixinJSBridge.log(res.err_msg);if( res.err_msg =="get_brand_wcpay_request:ok"){alert("支付成功!");}else{alert("支付失败!");}});}

在小程序里，我们是通过wx.requestPayment方法来调起支付功能，当然在这之前，我们先要获取prepay_id。

wx.request({url: 'https://yourwebsit/service/getPay', method: 'POST',data: {bookingNo:bookingNo, /*订单号*/total_fee:total_fee,  /*订单金额*/openid:openid},header: {'content-type': 'application/json'},success: function(res) {wx.requestPayment({//时间戳'timeStamp':timeStamp,'nonceStr': nonceStr, //随机串'package': 'prepay_id='+res.data.prepay_id, //配置支付id值'signType': 'MD5',//微信签名方式'paySign': res.data._paySignjs, //微信签名//成功后'success':function(res){ console.log(res);},'fail':function(res){console.log('fail:'+JSON.stringify(res));}})},fail: function(err) {console.log(err)}})

那在服务器端主要要实现的是prepay_id的获取和签名paySign

var bookingNo = req.param("bookingNo");var total_fee = req.param("total_fee");var openid = req.param("openid");var body = "费用说明";var url = "https://api.mch.weixin.qq.com/pay/unifiedorder";var formData = "<xml>";formData += "<appid>appid</appid>"; //appidformData += "<attach>test</attach>";formData += "<body>" + body + "</body>";formData += "<mch_id>mch_id</mch_id>"; //商户号formData += "<nonce_str>nonce_str</nonce_str>";formData += "<notify_url>notify_url</notify_url>";formData += "<openid>" + openid + "</openid>";formData += "<out_trade_no>" + bookingNo + "</out_trade_no>";formData += "<spbill_create_ip>spbill_create_ip</spbill_create_ip>";formData += "<total_fee>" + total_fee + "</total_fee>";formData += "<trade_type>JSAPI</trade_type>";formData += "<sign>" + paysignjsapi(appid, attach, body, mch_id, nonce_str, notify_url, openid, bookingNo, spbill_create_ip, total_fee, 'JSAPI') + "</sign>";formData += "</xml>";request({url: url,method: 'POST',body: formData}, function(err, response, body) {if(!err && response.statusCode == 200) {var prepay_id = getXMLNodeValue('prepay_id', body.toString("utf-8"));var tmp = prepay_id.split('[');var tmp1 = tmp[2].split(']');//签名var _paySignjs = paysignjs(appid, mch_id, 'prepay_id=' + tmp1[0], 'MD5',timeStamp);var o = {prepay_id: tmp1[0],_paySignjs: _paySignjs}res.send(o);}});

第四步调用这个函数

function paysignjs(appid, nonceStr, package, signType, timeStamp) {var ret = {appId: appid,nonceStr: nonceStr,package: package,signType: signType,timeStamp: timeStamp};var string = raw1(ret);string = string + '&key='+key;console.log(string);var crypto = require('crypto');return crypto.createHash('md5').update(string, 'utf8').digest('hex');
};function raw1(args) {var keys = Object.keys(args);keys = keys.sort()var newArgs = {};keys.forEach(function(key) {newArgs[key] = args[key];});var string = '';for(var k in newArgs) {string += '&' + k + '=' + newArgs[k];}string = string.substr(1);return string;
};function paysignjsapi(appid, attach, body, mch_id, nonce_str, notify_url, openid, out_trade_no, spbill_create_ip, total_fee, trade_type) {var ret = {appid: appid,attach: attach,body: body,mch_id: mch_id,nonce_str: nonce_str,notify_url: notify_url,openid: openid,out_trade_no: out_trade_no,spbill_create_ip: spbill_create_ip,total_fee: total_fee,trade_type: trade_type};var string = raw(ret);string = string + '&key='+key;var crypto = require('crypto');return crypto.createHash('md5').update(string, 'utf8').digest('hex');
};function raw(args) {var keys = Object.keys(args);keys = keys.sort()var newArgs = {};keys.forEach(function(key) {newArgs[key.toLowerCase()] = args[key];});var string = '';for(var k in newArgs) {string += '&' + k + '=' + newArgs[k];}string = string.substr(1);return string;
};function getXMLNodeValue(node_name, xml) {var tmp = xml.split("<" + node_name + ">");var _tmp = tmp[1].split("</" + node_name + ">");return _tmp[0];
}