推荐课程：java教程。
废话不多说，直接上代码：
paycontroller
@api(tags = 支付模块)@restcontroller@requestmapping()public class paycontroller { @apioperation(value = 请求支付接口) @requestmapping(value = /wxpay, method = requestmethod.post) public jsonobject wxpay(httpservletrequest request) { try { //生成的随机字符串 string nonce_str = getrandomstringbylength(32); //商品名称 string body = 测试商品名称; //获取客户端的ip地址 string spbill_create_ip = getipaddr(request); //组装参数，用户生成统一下单接口的签名 map<string, string> packageparams = new hashmap<>(); packageparams.put(appid, wechatconfig.appid); packageparams.put(mch_id, wechatconfig.mch_id); packageparams.put(nonce_str, nonce_str); packageparams.put(body, body); packageparams.put(out_trade_no, payorderid + );//商户订单号,自己的订单id packageparams.put(total_fee, 100 + );//支付金额，这边需要转成字符串类型，否则后面的签名会失败 packageparams.put(spbill_create_ip, spbill_create_ip); packageparams.put(notify_url, wechatconfig.notify_url);//支付成功后的回调地址 packageparams.put(trade_type, wechatconfig.tradetype);//支付方式 packageparams.put(openid, openid + );//用户的openid，自己获取 string prestr = payutil.createlinkstring(packageparams); // 把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串 //md5运算生成签名，这里是第一次签名，用于调用统一下单接口 string mysign = payutil.sign(prestr, wechatconfig.key, utf-8).touppercase(); //拼接统一下单接口使用的xml数据，要将上一步生成的签名一起拼接进去 string xml = <xml> + <appid> + wechatconfig.appid + </appid> + <body><![cdata[" + body + "]]></body> + <mch_id> + wechatconfig.mch_id + </mch_id> + <nonce_str> + nonce_str + </nonce_str> + <notify_url> + wechatconfig.notify_url + </notify_url> + <openid> + openid + </openid> + <out_trade_no> + payorderid + </out_trade_no> + <spbill_create_ip> + spbill_create_ip + </spbill_create_ip> + <total_fee> + 100 + </total_fee>//支付的金额，单位：分 + <trade_type> + wechatconfig.tradetype + </trade_type> + <sign> + mysign + </sign> + </xml>; //调用统一下单接口，并接受返回的结果 string result = payutil.httprequest(wechatconfig.pay_url, post, xml); // 将解析结果存储在hashmap中 map map = payutil.doxmlparse(result); string return_code = (string) map.get(return_code);//返回状态码 string result_code = (string) map.get(result_code);//返回状态码 map<string, object> response = new hashmap<string, object>();//返回给小程序端需要的参数 if (return_code == success && return_code.equals(result_code)) { string prepay_id = (string) map.get(prepay_id);//返回的预付单信息 response.put(noncestr, nonce_str); response.put(package, prepay_id= + prepay_id); long timestamp = system.currenttimemillis() / 1000; response.put(timestamp, timestamp + );//这边要将返回的时间戳转化成字符串，不然小程序端调用wx.requestpayment方法会报签名错误 //拼接签名需要的参数 string stringsigntemp = appid= + wechatconfig.appid + &noncestr= + nonce_str + &package=prepay_id= + prepay_id + &signtype=md5×tamp= + timestamp; //再次签名，这个签名用于小程序端调用wx.requesetpayment方法 string paysign = payutil.sign(stringsigntemp, wechatconfig.key, utf-8).touppercase(); response.put(paysign, paysign); } response.put(appid, wechatconfig.appid); return response.succ(response); } catch (exception e) { e.printstacktrace(); } return null; } //这里是支付回调接口，微信支付成功后会自动调用 @requestmapping(value = /wxnotify, method = requestmethod.post) public void wxnotify(httpservletrequest request, httpservletresponse response) throws exception { bufferedreader br = new bufferedreader(new inputstreamreader(request.getinputstream())); string line = null; stringbuilder sb = new stringbuilder(); while ((line = br.readline()) != null) { sb.append(line); } br.close(); //sb为微信返回的xml string notityxml = sb.tostring(); string resxml = ; map map = payutil.doxmlparse(notityxml); string returncode = (string) map.get(return_code); if (success.equals(returncode)) { //验证签名是否正确 map<string, string> validparams = payutil.parafilter(map); //回调验签时需要去除sign和空值参数 string prestr = payutil.createlinkstring(validparams); //根据微信官网的介绍，此处不仅对回调的参数进行验签，还需要对返回的金额与系统订单的金额进行比对等 if (payutil.verify(prestr, (string) map.get(sign), wechatconfig.key, utf-8)) { /**此处添加自己的业务逻辑代码start**/ //注意要判断微信支付重复回调，支付成功后微信会重复的进行回调 /**此处添加自己的业务逻辑代码end**/ //通知微信服务器已经支付成功 resxml = <xml> + <return_code><![cdata[success]]></return_code> + <return_msg><![cdata[ok]]></return_msg> + </xml> ; } } else { resxml = <xml> + <return_code><![cdata[fail]]></return_code> + <return_msg><![cdata[报文为空]]></return_msg> + </xml> ; } bufferedoutputstream out = new bufferedoutputstream( response.getoutputstream()); out.write(resxml.getbytes()); out.flush(); out.close(); } //获取随机字符串 private string getrandomstringbylength(int length) { string base = abcdefghijklmnopqrstuvwxyz0123456789; random random = new random(); stringbuffer sb = new stringbuffer(); for (int i = 0; i < length; i++) { int number = random.nextint(base.length()); sb.append(base.charat(number)); } return sb.tostring(); } //获取ip private string getipaddr(httpservletrequest request) { string ip = request.getheader("x-forwarded-for"); if (stringutils.isnotempty(ip) && !"unknown".equalsignorecase(ip)) { //多次反向代理后会有多个ip值，第一个ip才是真实ip int index = ip.indexof(","); if (index != -1) { return ip.substring(0, index); } else { return ip; } } ip = request.getheader("x-real-ip"); if (stringutils.isnotempty(ip) && !"unknown".equalsignorecase(ip)) { return ip; } return request.getremoteaddr(); }}
上面代码用到了payutil和wechatconfig这两个类，一个是配置类，一个是工具类，代码如下：
payutil
public class payutil { /** * 签名字符串 * * @param text 需要签名的字符串 * @param key 密钥 * @param input_charset 编码格式 * @return 签名结果 */ public static string sign(string text, string key, string input_charset) { text = text + "&key=" + key; return digestutils.md5hex(getcontentbytes(text, input_charset)); } /** * 签名字符串 * * @param text 需要签名的字符串 * @param sign 签名结果 * @param key 密钥 * @param input_charset 编码格式 * @return 签名结果 */ public static boolean verify(string text, string sign, string key, string input_charset) { text = text + key; string mysign = digestutils.md5hex(getcontentbytes(text, input_charset)); if (mysign.equals(sign)) { return true; } else { return false; } } /** * @param content * @param charset * @return * @throws java.security.signatureexception * @throws unsupportedencodingexception */ public static byte[] getcontentbytes(string content, string charset) { if (charset == null || "".equals(charset)) { return content.getbytes(); } try { return content.getbytes(charset); } catch (unsupportedencodingexception e) { throw new runtimeexception("md5签名过程中出现错误,指定的编码集不对,您目前指定的编码集是:" + charset); } } private static boolean isvalidchar(char ch) { if ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z') || (ch >= 'a' && ch <= 'z')) return true; if ((ch >= 0x4e00 && ch <= 0x7fff) || (ch >= 0x8000 && ch <= 0x952f)) return true;// 简体中文汉字编码 return false; } /** * 除去数组中的空值和签名参数 * * @param sarray 签名参数组 * @return 去掉空值与签名参数后的新签名参数组 */ public static map<string, string> parafilter(map<string, string> sarray) { map<string, string> result = new hashmap<string, string>(); if (sarray == null || sarray.size() <= 0) { return result; } for (string key : sarray.keyset()) { string value = sarray.get(key); if (value == null || value.equals() || key.equalsignorecase(sign) || key.equalsignorecase(sign_type)) { continue; } result.put(key, value); } return result; } /** * 把数组所有元素排序，并按照“参数=参数值”的模式用“&”字符拼接成字符串 * * @param params 需要排序并参与字符拼接的参数组 * @return 拼接后字符串 */ public static string createlinkstring(map<string, string> params) { list<string> keys = new arraylist<>(params.keyset()); collections.sort(keys); string prestr = ; for (int i = 0; i < keys.size(); i++) { string key = keys.get(i); string value = params.get(key); if (i == keys.size() - 1) {// 拼接时，不包括最后一个&字符 prestr = prestr + key + "=" + value; } else { prestr = prestr + key + "=" + value + "&"; } } return prestr; } /** * @param requesturl 请求地址 * @param requestmethod 请求方法 * @param outputstr 参数 */ public static string httprequest(string requesturl, string requestmethod, string outputstr) { // 创建sslcontext stringbuffer buffer = null; try { url url = new url(requesturl); httpurlconnection conn = (httpurlconnection) url.openconnection(); conn.setrequestmethod(requestmethod); conn.setdooutput(true); conn.setdoinput(true); conn.connect(); //往服务器端写内容 if (null != outputstr) { outputstream os = conn.getoutputstream(); os.write(outputstr.getbytes("utf-8")); os.close(); } // 读取服务器端返回的内容 inputstream is = conn.getinputstream(); inputstreamreader isr = new inputstreamreader(is, "utf-8"); bufferedreader br = new bufferedreader(isr); buffer = new stringbuffer(); string line = null; while ((line = br.readline()) != null) { buffer.append(line); } br.close(); } catch (exception e) { e.printstacktrace(); } return buffer.tostring(); } public static string urlencodeutf8(string source) { string result = source; try { result = java.net.urlencoder.encode(source, "utf-8"); } catch (unsupportedencodingexception e) { // todo auto-generated catch block e.printstacktrace(); } return result; } /** * 解析xml,返回第一级元素键值对。如果第一级元素有子节点，则此节点的值是子节点的xml数据。 * * @param strxml * @return * @throws org.jdom2.jdomexception * @throws ioexception */ public static map doxmlparse(string strxml) throws exception { if (null == strxml || "".equals(strxml)) { return null; } map m = new hashmap(); inputstream in = string2inputstream(strxml); saxbuilder builder = new saxbuilder(); document doc = builder.build(in); element root = doc.getrootelement(); list list = root.getchildren(); iterator it = list.iterator(); while (it.hasnext()) { element e = (element) it.next(); string k = e.getname(); string v = ""; list children = e.getchildren(); if (children.isempty()) { v = e.gettextnormalize(); } else { v = getchildrentext(children); } m.put(k, v); } //关闭流 in.close(); return m; } /** * 获取子结点的xml * * @param children * @return string */ public static string getchildrentext(list children) { stringbuffer sb = new stringbuffer(); if (!children.isempty()) { iterator it = children.iterator(); while (it.hasnext()) { element e = (element) it.next(); string name = e.getname(); string value = e.gettextnormalize(); list list = e.getchildren(); sb.append("<" + name + ">); if (!list.isempty()) { sb.append(getchildrentext(list)); } sb.append(value); sb.append(</" + name + ">); } } return sb.tostring(); } public static inputstream string2inputstream(string str) { return new bytearrayinputstream(str.getbytes()); }}
wechatconfig
public class wechatconfig { //小程序appid public static final string appid = ; //微信支付的商户id public static final string mch_id = ; //微信支付的商户密钥 public static final string key = ; //支付成功后的服务器回调url，这里填paycontroller里的回调函数地址 public static final string notify_url = ; //签名方式，固定值 public static final string signtype = md5; //交易类型，小程序支付的固定值为jsapi public static final string tradetype = jsapi; //微信统一下单接口地址 public static final string pay_url = https://api.mch.weixin.qq.com/pay/unifiedorder;}
在刚刚开始接触小程序支付的时候，也觉得比较的棘手，因为自己并没有写过支付相关的代码。后来通过百度查找资料和阅读官方文档，最后把这个支付的controller完成了。最后，一定要多读几遍官方文档，然后结合paycontroller的代码去看，就会发现其实支付也不是很难。
以上就是小程序后端用什么写的详细内容。