首先观看微信提供的文档

https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_api.php?chapter=7_3&index=1

清楚调用微信支付必须传递的参数

因为微信提供了小程序唤起微信支付的方法，后端只需要传递对应的参数给前端即可

首先在程序中配置申请的固定参数

wx.open.app_id=用户的appidwx.open.app_secret=这是做登陆用的weixin.pay.partner=商户号wexxin.pay.partenerkey=商户号秘钥

编写工具类实现对固定值的读取

@Component//@PropertySource("classpath:application.properties")public class ConstantPropertiesUtil implements InitializingBean {//读取配置文件并赋值@Value("${wx.open.app_id}")private String appId;@Value("${wx.open.app_secret}")private String appSecret;@Value("{weixin.pay.partner}")private String partner;@Value("{wexxin.pay.partenerkey}")private String partenerkey;public static String WX_OPEN_APP_ID;public static String WX_OPEN_APP_SECRET;public static String PARTNER;public static String PARTNERKET;@Overridepublic void afterPropertiesSet() throws Exception {WX_OPEN_APP_ID = appId;WX_OPEN_APP_SECRET = appSecret;PARTNER = partner;PARTNERKET = partenerkey;}}

当用户点击购买会生成订单，这里代码省略

点击登陆时调用后端传给前端需要的值

对应微信文档https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=9_1

 可以看到，除了一些固定值，需要我们自己处理的有

签名：根据文档可以发现签名是有一定要求的

 简单来说就将其他传入固定值字段进行排序拼接，在根据商家号的key进行加密处理。

支付接口

@Autowiredprivate WXService wxService;@GetMapping("pay")public R creatNative(Integer orderid){try {Map map = wxService.payment(orderid);return R.ok().data(map);} catch (UnsupportedEncodingException e) {return R.error().message("支付失败");}}

编写service逻辑，根据文档进行传值

@Servicepublic class WXServiceImpl implements WXService {@Autowiredprivate OrderService orderService;@Overridepublic Map payment(Integer orderid) throws UnsupportedEncodingException {//封装传递微信地址参数Map paramMap = new HashMap();paramMap.put("appid", ConstantPropertiesUtil.WX_OPEN_APP_ID); //公众号idparamMap.put("mch_id", ConstantPropertiesUtil.PARTNER); //商户号paramMap.put("nonce_str", WXPayUtil.generateNonceStr()); //随机字符串，调用工具类paramMap.put("out_trade_no", orderid); //订单流水号Order order = orderService.getById(orderid);paramMap.put("total_fee", order.getPayment()); //金额paramMap.put("spbill_create_ip", "127.0.0.1"); //终端ipparamMap.put("notify_url", "http://XXXXX/weixin/callBack");//回调地址paramMap.put("body",order.getProductname()); //商品名称paramMap.put("timeStamp", WXUtil.getCurrentTimestamp()+"");//获取当前时间戳，单位秒String sign = WXUtil.genSignature(ConstantPropertiesUtil.PARTNERKET,paramMap); //singparamMap.put("sign", sign); //签名return paramMap;}}

签名工具类，以及时间戳方法

public class WXUtil {public static String genSignature(String secretKey, Map<String, String> params) throws UnsupportedEncodingException {if (secretKey == null || params == null || params.size() == 0) {return "";}// 1. 参数名按照ASCII码表升序排序String[] keys = params.keySet().toArray(new String[0]);Arrays.sort(keys);// 2. 按照排序拼接参数名与参数值StringBuffer paramBuffer = new StringBuffer();for (String key : keys) {paramBuffer.append("&"+key).append(params.get(key) == null ? "" : "="+params.get(key));}// 3. 将secretKey拼接到最后paramBuffer=paramBuffer.append("&key="+secretKey);String pa =paramBuffer.substring(1);// 4. MD5是128位长度的摘要算法，用16进制表示，一个十六进制的字符能表示4个位，所以签名后的字符串长度固定为32个十六进制字符。return DigestUtils.md5Hex(pa.getBytes("UTF-8")).toUpperCase();}/*** 获取当前时间戳，单位秒* @return*/public static long getCurrentTimestamp() {return System.currentTimeMillis()/1000;}/*** 获取当前时间戳，单位毫秒* @return*/public static long getCurrentTimestampMs() {return System.currentTimeMillis();}}

此时即可完成支付，微信支付后，微信会给我们回调地址进行发送信息，由此我们可以判断支付状态以及获取微信支付返回的参数

回调接口

//回调接口@RequestMapping("callBack")public String callBack(HttpServletRequest request, HttpServletResponse response) throws Exception{System.out.println("接口已被调用");ServletInputStream inputStream = request.getInputStream();String notifyXml = StreamUtils.inputStream2String(inputStream, "utf-8");System.out.println(notifyXml);// 解析返回结果Map<String, String> notifyMap = WXPayUtil.xmlToMap(notifyXml);// 判断支付是否成功if ("SUCCESS".equals(notifyMap.get("result_code"))) {//编写自己的实现逻辑// 支付成功：给微信发送我已接收通知的响应// 创建响应对象Map<String, String> returnMap = new HashMap<>();returnMap.put("return_code", "SUCCESS");returnMap.put("return_msg", "OK");String returnXml = WXPayUtil.mapToXml(returnMap);response.setContentType("text/xml");System.out.println("支付成功");return returnXml;}}// 创建响应对象：微信接收到校验失败的结果后，会反复的调用当前回调函数Map<String, String> returnMap = new HashMap<>();returnMap.put("return_code", "FAIL");returnMap.put("return_msg", "");String returnXml = WXPayUtil.mapToXml(returnMap);response.setContentType("text/xml");System.out.println("校验失败");return returnXml;}

接收输入流转换工具类

public class StreamUtils {private static int _buffer_size = 1024;/*** InputStream流转换成String字符串* @param inStream InputStream流* @param encoding 编码格式* @return String字符串*/public static String inputStream2String(InputStream inStream, String encoding){String result = null;ByteArrayOutputStream outStream = null;try {if(inStream != null){outStream = new ByteArrayOutputStream();byte[] tempBytes = new byte[_buffer_size];int count = -1;while((count = inStream.read(tempBytes, 0, _buffer_size)) != -1){outStream.write(tempBytes, 0, count);}tempBytes = null;outStream.flush();result = new String(outStream.toByteArray(), encoding);outStream.close();}} catch (Exception e) {result = null;} finally {try {if(inStream != null) {inStream.close();inStream = null;}if(outStream != null) {outStream.close();outStream = null;}} catch (IOException e) {e.printStackTrace();}}return result;}}