简介：微信小程序支付这里的坑还是有的，所以提醒各位在编写的一定要注意！！！
1.首先呢，你需要准备openid，appid，还有申请微信支付后要设置一个32位的密钥，需要先生成一个sign，得到prepay_id，然后再得到一个paySign，总之就是很墨迹，下面献上我的controller
//微信下单支付@ResponseBody@RequestMapping("doOrder")public void doOrder(HttpServletRequest request, HttpServletResponse response) throws IOException, JDOMException {request.setCharacterEncoding("UTF-8");response.setCharacterEncoding("UTF-8");//得到openidString openid = request.getParameter("openid");int fee = 0;//得到小程序传过来的价格，注意这里的价格必须为整数，1代表1分，所以传过来的值必须*100；if (null != request.getParameter("price")) {fee = Integer.parseInt(request.getParameter("price").toString());}System.out.println(request.getParameter("price"));System.out.println(fee);//订单编号String did = request.getParameter("did");//订单标题String title = request.getParameter("title");//时间戳String times = System.currentTimeMillis() + "";SortedMap<Object, Object> packageParams = new TreeMap<Object, Object>();packageParams.put("appid", "wxa**********2e2");packageParams.put("mch_id", "1486425722");packageParams.put("nonce_str", times);//时间戳packageParams.put("body", title);//支付主体packageParams.put("out_trade_no", did);//编号packageParams.put("total_fee", fee);//价格// packageParams.put("spbill_create_ip", getIp2(request));这里之前加了ip，但是总是获取sign失败，原因不明，之后就注释掉了packageParams.put("notify_url", base+"/notify");//支付回调接口，用于支付成功后处理业务逻辑，小程序端支付success不能保证100%回调成功，建议采用后端异步回调处理方式，回调方法在最后packageParams.put("trade_type", "JSAPI");//这个api有，固定的packageParams.put("openid", openid);//openid//获取signString sign = PayCommonUtil.createSign("UTF-8", packageParams, "x********************************4");//最后这个是自己设置的32位密钥packageParams.put("sign", sign);//转成XMLString requestXML = PayCommonUtil.getRequestXml(packageParams);System.out.println(requestXML);//得到含有prepay_id的XMLString resXml = HttpUtil.postData("https://api.mch./pay/unifiedorder", requestXML);System.out.println(resXml);//解析XML存入MapMap map = XMLUtil.doXMLParse(resXml);System.out.println(map);// String return_code = (String) map.get("return_code");//得到prepay_idString prepay_id = (String) map.get("prepay_id");SortedMap<Object, Object> packageP = new TreeMap<Object, Object>();packageP.put("appId", "wxa**********2e2");//！！！注意，这里是appId,上面是appid，真怀疑写这个东西的人。。。packageP.put("nonceStr", times);//时间戳packageP.put("package", "prepay_id=" + prepay_id);//必须把package写成 "prepay_id="+prepay_id这种形式packageP.put("signType", "MD5");//paySign加密packageP.put("timeStamp", (System.currentTimeMillis() / 1000) + "");//得到paySignString paySign = PayCommonUtil.createSign("UTF-8", packageP, "x********************************4");packageP.put("paySign", paySign);//将packageP数据返回给小程序Gson gson = new Gson();String json = gson.toJson(packageP);PrintWriter pw = response.getWriter();System.out.println(json);pw.write(json);pw.close();}```java/*** 此函数会被执行多次，如果支付状态已经修改为已支付，则下次再调的时候判断是否已经支付，如果已经支付了，则什么也执行* @param request* @param response* @return* @throws IOException* @throws JDOMException*/@RequestMapping(value = "notify", produces = MediaType.APPLICATION_JSON_VALUE)// @RequestDescription("支付回调地址")@ResponseBodypublic String notify(HttpServletRequest request, HttpServletResponse response) throws IOException, JDOMException {System.out.println("微信支付回调");InputStream inStream = request.getInputStream();ByteArrayOutputStream outSteam = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len = 0;while ((len = inStream.read(buffer)) != -1) {outSteam.write(buffer, 0, len);}String resultxml = new String(outSteam.toByteArray(), "utf-8");Map params = PayCommonUtil.doXMLParse(resultxml);outSteam.close();inStream.close();Map return_data = new HashMap();if (!PayCommonUtil.isTenpaySign(params)) {// 支付失败return_data.put("return_code", "FAIL");return_data.put("return_msg", "return_code不正确");return StringUtil.GetMapToXML(return_data);} else {System.out.println("===============付款成功==============");// ------------------------------// 处理业务开始// ------------------------------// 此处处理订单状态，结合自己的订单数据完成订单状态的更新// ------------------------------String total_fee = params.get("total_fee");double v = Double.valueOf(total_fee) / 100;String out_trade_no = String.valueOf(Long.parseLong(params.get("out_trade_no").split("O")[0]));Date accountTime = DateUtil.stringtoDate(params.get("time_end"), "yyyyMMddHHmmss");String ordertime = DateUtil.dateToString(new Date(), "yyyy-MM-dd HH:mm:ss");String totalAmount = String.valueOf(v);String appId = params.get("appid");String tradeNo = params.get("transaction_id");return_data.put("return_code", "SUCCESS");return_data.put("return_msg", "OK");return StringUtil.GetMapToXML(return_data);}}}`public static String GetMapToXML(Map param){StringBuffer sb = new StringBuffer();sb.append("");for (Map.Entry entry : param.entrySet()) {sb.append("");sb.append(entry.getValue());sb.append(""+ entry.getKey() +">");}sb.append("");return sb.toString();}```java
.下面是需要用到的工具类（1）.生成sign以及得到sign后生成XML工具类PayCommonUtil```javapublic class PayCommonUtil {/** * 是否签名正确,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。 * @return boolean */ public static boolean isTenpaySign(String characterEncoding, SortedMap<Object, Object> packageParams, String API_KEY) { StringBuffer sb = new StringBuffer(); Set es = packageParams.entrySet(); Iterator it = es.iterator(); while(it.hasNext()) { Map.Entry entry = (Map.Entry)it.next(); String k = (String)entry.getKey(); String v = (String)entry.getValue(); if(!"sign".equals(k) && null != v && !"".equals(v)) { sb.append(k + "=" + v + "&"); } } sb.append("key=" + API_KEY); //算出摘要 String mysign = MD5.MD5Encode(sb.toString(), characterEncoding).toLowerCase(); String tenpaySign = ((String)packageParams.get("sign")).toLowerCase(); //System.out.println(tenpaySign + " " + mysign); return tenpaySign.equals(mysign); } /** * @author * @Description：sign签名 * @param characterEncoding * 编码格式 * @param parameters * 请求参数 * @return */ public static String createSign(String characterEncoding, SortedMap<Object, Object> packageParams, String API_KEY) { StringBuffer sb = new StringBuffer(); Set es = packageParams.entrySet(); Iterator it = es.iterator(); while (it.hasNext()) { Map.Entry entry = (Map.Entry) it.next(); String k = entry.getKey().toString(); String v = entry.getValue().toString(); if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) { sb.append(k + "=" + v + "&"); } } sb.append("key=" + API_KEY); String sign = MD5.MD5Encode(sb.toString(), characterEncoding).toUpperCase(); return sign; } /** * @author * @Description：将请求参数转换为xml格式的string * @param parameters * 请求参数 * @return */ public static String getRequestXml(SortedMap<Object, Object> parameters) { StringBuffer sb = new StringBuffer(); sb.append("<xml>"); Set es = parameters.entrySet(); Iterator it = es.iterator(); while (it.hasNext()) { Map.Entry entry = (Map.Entry) it.next(); String k = entry.getKey().toString(); String v = entry.getValue().toString(); if ("attach".equalsIgnoreCase(k) || "body".equalsIgnoreCase(k) || "sign".equalsIgnoreCase(k)) { sb.append("<" + k + ">" + "<![CDATA[" + v + "]]></" + k + ">"); } else { sb.append("<" + k + ">" + v + "</" + k + ">"); } } sb.append("</xml>"); return sb.toString(); } /** * 取出一个指定长度大小的随机正整数. * * @param length * int 设定所取出随机数的长度。length小于11 * @return int 返回生成的随机数。 */ public static int buildRandom(int length) { int num = 1; double random = Math.random(); if (random < 0.1) { random = random + 0.1; } for (int i = 0; i < length; i++) { num = num * 10; } return (int) ((random * num)); } /** * 获取当前时间 yyyyMMddHHmmss * * @return String */ public static String getCurrTime() { Date now = new Date(); SimpleDateFormat outFormat = new SimpleDateFormat("yyyyMMddHHmmss"); String s = outFormat.format(now); return s; } }
（2）.访问官方接口得到含有prepay_id的XML工具类HttpUtil
public class HttpUtil {//private static final Log logger = Logs.get(); private final static int CONNECT_TIMEOUT = 5000; // in milliseconds private final static String DEFAULT_ENCODING = "UTF-8"; public static String postData(String urlStr, String data){return postData(urlStr, data, null); } public static String postData(String urlStr, String data, String contentType){BufferedReader reader = null; try {URL url = new URL(urlStr); URLConnection conn = url.openConnection(); conn.setDoOutput(true); conn.setConnectTimeout(CONNECT_TIMEOUT); conn.setReadTimeout(CONNECT_TIMEOUT); if(contentType != null) conn.setRequestProperty("content-type", contentType); OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream(), DEFAULT_ENCODING); if(data == null) data = ""; writer.write(data); writer.flush(); writer.close(); reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), DEFAULT_ENCODING)); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) {sb.append(line); sb.append("\r\n"); } return sb.toString(); } catch (IOException e) {//logger.error("Error connecting to " + urlStr + ": " + e.getMessage()); } finally {try {if (reader != null) reader.close(); } catch (IOException e) {} } return null; } }
（3）.解析XML工具类
public class XMLUtil {public static Map doXMLParse(String strxml) throws JDOMException, IOException {strxml = strxml.replaceFirst("encoding=\".*\"", "encoding=\"UTF-8\""); if(null == strxml || "".equals(strxml)) {return null; } Map m = new HashMap(); InputStream in = new ByteArrayInputStream(strxml.getBytes("UTF-8")); 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 = XMLUtil.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(XMLUtil.getChildrenText(list)); } sb.append(value); sb.append("</" + name + ">"); } } return sb.toString(); } }
（4）.MD5加密工具类
public class MD5 {private static String byteArrayToHexString(byte b[]) {StringBuffer resultSb = new StringBuffer();for (int i = 0; i < b.length; i++)resultSb.append(byteToHexString(b[i]));return resultSb.toString();}private static String byteToHexString(byte b) {int n = b;if (n < 0)n += 256;int d1 = n / 16;int d2 = n % 16;return hexDigits[d1] + hexDigits[d2];}public static String MD5Encode(String origin, String charsetname) {String resultString = null;try {resultString = new String(origin);MessageDigest md = MessageDigest.getInstance("MD5");if (charsetname == null || "".equals(charsetname))resultString = byteArrayToHexString(md.digest(resultString.getBytes()));elseresultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));} catch (Exception exception) {}return resultString;}private static final String hexDigits[] = {"0", "1", "2", "3", "4", "5","6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };}
3.小程序支付函数
gopay: function () {var that = thiswx.request({url: app.baseurl + 'doOrder',data: {'openid': wx.getStorageSync('openids'),'title': that.data.title,'did': that.data.did,'price': that.data.price*100},method: 'POST',header: {"content-type": 'application/x-www-form-urlencoded'},success: function (res) {console.log(res.data)console.log(res.data.timeStamp)console.log(res.data.nonceStr)console.log(res.data.package)console.log(res.data.paySign)wx.requestPayment({timeStamp: res.data.timeStamp,nonceStr: res.data.nonceStr,package: res.data.package,signType: res.data.signType,paySign: res.data.paySign,success: function (res) {console.log('支付调用成功',res)},fail: function (res) {console.log(res)}})}})}
4、支付成功回调
/*** 此函数会被执行多次，如果支付状态已经修改为已支付，则下次再调的时候判断是否已经支付，如果已经支付了，则什么也执行* @param request* @param response* @return* @throws IOException* @throws JDOMException*/@RequestMapping(value = "notify")@ResponseBodypublic String notify(HttpServletRequest request, HttpServletResponse response) throws IOException {String resXml = "";System.out.println("微信支付回调");//resultxml中含用户订单号等信息，解析后用于处理订单Map<String, String> params = PayCommonUtil.doXMLParse(resultxml);if (!PayCommonUtil.isTenpaySign(params)) {// 支付失败resXml = "<xml>" + "<return_code><![CDATA[FAIL]]></return_code>"+ "<return_msg><![CDATA[报文为空]]></return_msg>" + "</xml> ";} else {System.out.println("==========付款成功==========");// ------------------------------// 处理业务开始// ------------------------------// 此处处理订单状态，结合自己的订单数据完成订单状态的更新// ------------------------------//通知微信.异步确认成功.必写.不然会一直通知后台.八次之后就认为交易失败了resXml = "<xml>" + "<return_code><![CDATA[SUCCESS]]></return_code>"+ "<return_msg><![CDATA[OK]]></return_msg>" + "</xml> ";}BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());out.write(resXml.getBytes());out.flush();out.close();}
结束啦，小程序支付的java后台就这些。
