application-dev.yml

sky:
  wechat:
    appid: xxxxx
    secret: xxxxx
    mchid : xxxx
    mchSerialNo: xxxx
    privateKeyFilePath: D:\xxxx.pem
    apiV3Key: xxxx
    weChatPayCertFilePath: D:\xxxxx.pem
    notifyUrl: https://www.weixin.qq.com/wxpay/pay.php
    refundNotifyUrl: https://www.weixin.qq.com/wxpay/pay.php

application.yml

sky:
  wechat:
    appid: ${sky.wechat.appid}
    secret: ${sky.wechat.secret}
    mchid : ${sky.wechat.mchid}
    mchSerialNo: ${sky.wechat.mchSerialNo}
    privateKeyFilePath: ${sky.wechat.privateKeyFilePath}
    apiV3Key: ${sky.wechat.apiV3Key}
    weChatPayCertFilePath: ${sky.wechat.weChatPayCertFilePath}
    notifyUrl: ${sky.wechat.notifyUrl}
    refundNotifyUrl: ${sky.wechat.refundNotifyUrl}

WeChatProperties.java：读取配置(已定义)

package com.sky.properties;

import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "sky.wechat")
@Data
public class WeChatProperties {

    private String appid; //小程序的appid
    private String secret; //小程序的秘钥
    private String mchid; //商户号
    private String mchSerialNo; //商户API证书的证书序列号
    private String privateKeyFilePath; //商户私钥文件
    private String apiV3Key; //证书解密的密钥
    private String weChatPayCertFilePath; //平台证书
    private String notifyUrl; //支付成功的回调地址
    private String refundNotifyUrl; //退款成功的回调地址
}

Mapper层

    /**
     * 根据订单号和用户id查询订单
     * @param orderNumber
     * @param userId
     */
    @Select("select * from orders where number = #{orderNumber} and user_id= #{userId}")
    Orders getByNumberAndUserId(String orderNumber, Long userId);

    /**
     * 修改订单信息
     * @param orders
     */
    void update(Orders orders);

在OrderMapper.xml中添加

<update id="update" parameterType="com.sky.entity.Orders">
        update orders
        <set>
            <if test="cancelReason != null and cancelReason!='' ">
                cancel_reason=#{cancelReason},
            </if>
            <if test="rejectionReason != null and rejectionReason!='' ">
                rejection_reason=#{rejectionReason},
            </if>
            <if test="cancelTime != null">
                cancel_time=#{cancelTime},
            </if>
            <if test="payStatus != null">
                pay_status=#{payStatus},
            </if>
            <if test="payMethod != null">
                pay_method=#{payMethod},
            </if>
            <if test="checkoutTime != null">
                checkout_time=#{checkoutTime},
            </if>
            <if test="status != null">
                status = #{status},
            </if>
            <if test="deliveryTime != null">
                delivery_time = #{deliveryTime}
            </if>
        </set>
        where id = #{id}
</update>

Service层

    /**
     * 订单支付
     * @param ordersPaymentDTO
     * @return
     */
    OrderPaymentVO payment(OrdersPaymentDTO ordersPaymentDTO) throws Exception;

    /**
     * 支付成功，修改订单状态
     * @param outTradeNo
     */
    void paySuccess(String outTradeNo);

    @Autowired
    private UserMapper userMapper;
    @Autowired
    private WeChatPayUtil weChatPayUtil;
    /**
     * 订单支付
     *
     * @param ordersPaymentDTO
     * @return
     */
    public OrderPaymentVO payment(OrdersPaymentDTO ordersPaymentDTO) throws Exception {
        // 当前登录用户id
        Long userId = BaseContext.getCurrentId();
        User user = userMapper.getById(userId);

        //调用微信支付接口，生成预支付交易单
        JSONObject jsonObject = weChatPayUtil.pay(
                ordersPaymentDTO.getOrderNumber(), //商户订单号
                new BigDecimal(0.01), //支付金额，单位 元
                "外卖订单", //商品描述
                user.getOpenid() //微信用户的openid
        );

        if (jsonObject.getString("code") != null && jsonObject.getString("code").equals("ORDERPAID")) {
            throw new OrderBusinessException("该订单已支付");
        }

        OrderPaymentVO vo = jsonObject.toJavaObject(OrderPaymentVO.class);
        vo.setPackageStr(jsonObject.getString("package"));

        return vo;
    }

    /**
     * 支付成功，修改订单状态
     *
     * @param outTradeNo
     */
    public void paySuccess(String outTradeNo) {
        // 当前登录用户id
        Long userId = BaseContext.getCurrentId();

        // 根据订单号查询当前用户的订单
        Orders ordersDB = orderMapper.getByNumberAndUserId(outTradeNo, userId);

        // 根据订单id更新订单的状态、支付方式、支付状态、结账时间
        Orders orders = Orders.builder()
                .id(ordersDB.getId())
                .status(Orders.TO_BE_CONFIRMED)
                .payStatus(Orders.PAID)
                .checkoutTime(LocalDateTime.now())
                .build();

        orderMapper.update(orders);
    }

/**
 * 微信支付工具类
 */
@Component
public class WeChatPayUtil {

    //微信支付下单接口地址
    public static final String JSAPI = "https://api.mch.weixin.qq.com/v3/pay/transactions/jsapi";

    //申请退款接口地址
    public static final String REFUNDS = "https://api.mch.weixin.qq.com/v3/refund/domestic/refunds";

    @Autowired
    private WeChatProperties weChatProperties;

    /**
     * 获取调用微信接口的客户端工具对象
     *
     * @return
     */
    private CloseableHttpClient getClient() {
        PrivateKey merchantPrivateKey = null;
        try {
            //merchantPrivateKey商户API私钥，如何加载商户API私钥请看常见问题
            merchantPrivateKey = PemUtil.loadPrivateKey(new FileInputStream(new File(weChatProperties.getPrivateKeyFilePath())));
            //加载平台证书文件
            X509Certificate x509Certificate = PemUtil.loadCertificate(new FileInputStream(new File(weChatProperties.getWeChatPayCertFilePath())));
            //wechatPayCertificates微信支付平台证书列表。你也可以使用后面章节提到的“定时更新平台证书功能”，而不需要关心平台证书的来龙去脉
            List<X509Certificate> wechatPayCertificates = Arrays.asList(x509Certificate);

            WechatPayHttpClientBuilder builder = WechatPayHttpClientBuilder.create()
                    .withMerchant(weChatProperties.getMchid(), weChatProperties.getMchSerialNo(), merchantPrivateKey)
                    .withWechatPay(wechatPayCertificates);

            // 通过WechatPayHttpClientBuilder构造的HttpClient，会自动的处理签名和验签
            CloseableHttpClient httpClient = builder.build();
            return httpClient;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 发送post方式请求
     *
     * @param url
     * @param body
     * @return
     */
    private String post(String url, String body) throws Exception {
        CloseableHttpClient httpClient = getClient();

        HttpPost httpPost = new HttpPost(url);
        httpPost.addHeader(HttpHeaders.ACCEPT, ContentType.APPLICATION_JSON.toString());
        httpPost.addHeader(HttpHeaders.CONTENT_TYPE, ContentType.APPLICATION_JSON.toString());
        httpPost.addHeader("Wechatpay-Serial", weChatProperties.getMchSerialNo());
        httpPost.setEntity(new StringEntity(body, "UTF-8"));

        CloseableHttpResponse response = httpClient.execute(httpPost);
        try {
            String bodyAsString = EntityUtils.toString(response.getEntity());
            return bodyAsString;
        } finally {
            httpClient.close();
            response.close();
        }
    }

    /**
     * 发送get方式请求
     *
     * @param url
     * @return
     */
    private String get(String url) throws Exception {
        CloseableHttpClient httpClient = getClient();

        HttpGet httpGet = new HttpGet(url);
        httpGet.addHeader(HttpHeaders.ACCEPT, ContentType.APPLICATION_JSON.toString());
        httpGet.addHeader(HttpHeaders.CONTENT_TYPE, ContentType.APPLICATION_JSON.toString());
        httpGet.addHeader("Wechatpay-Serial", weChatProperties.getMchSerialNo());

        CloseableHttpResponse response = httpClient.execute(httpGet);
        try {
            String bodyAsString = EntityUtils.toString(response.getEntity());
            return bodyAsString;
        } finally {
            httpClient.close();
            response.close();
        }
    }

    /**
     * jsapi下单
     *
     * @param orderNum    商户订单号
     * @param total       总金额
     * @param description 商品描述
     * @param openid      微信用户的openid
     * @return
     */
    private String jsapi(String orderNum, BigDecimal total, String description, String openid) throws Exception {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("appid", weChatProperties.getAppid());
        jsonObject.put("mchid", weChatProperties.getMchid());
        jsonObject.put("description", description);
        jsonObject.put("out_trade_no", orderNum);
        jsonObject.put("notify_url", weChatProperties.getNotifyUrl());

        JSONObject amount = new JSONObject();
        amount.put("total", total.multiply(new BigDecimal(100)).setScale(2, BigDecimal.ROUND_HALF_UP).intValue());
        amount.put("currency", "CNY");

        jsonObject.put("amount", amount);

        JSONObject payer = new JSONObject();
        payer.put("openid", openid);

        jsonObject.put("payer", payer);

        String body = jsonObject.toJSONString();
        return post(JSAPI, body);
    }

    /**
     * 小程序支付
     *
     * @param orderNum    商户订单号
     * @param total       金额，单位 元
     * @param description 商品描述
     * @param openid      微信用户的openid
     * @return
     */
    public JSONObject pay(String orderNum, BigDecimal total, String description, String openid) throws Exception {
        //统一下单，生成预支付交易单
        String bodyAsString = jsapi(orderNum, total, description, openid);
        //解析返回结果
        JSONObject jsonObject = JSON.parseObject(bodyAsString);
        System.out.println(jsonObject);

        String prepayId = jsonObject.getString("prepay_id");
        if (prepayId != null) {
            String timeStamp = String.valueOf(System.currentTimeMillis() / 1000);
            String nonceStr = RandomStringUtils.randomNumeric(32);
            ArrayList<Object> list = new ArrayList<>();
            list.add(weChatProperties.getAppid());
            list.add(timeStamp);
            list.add(nonceStr);
            list.add("prepay_id=" + prepayId);
            //二次签名，调起支付需要重新签名
            StringBuilder stringBuilder = new StringBuilder();
            for (Object o : list) {
                stringBuilder.append(o).append("\n");
            }
            String signMessage = stringBuilder.toString();
            byte[] message = signMessage.getBytes();

            Signature signature = Signature.getInstance("SHA256withRSA");
            signature.initSign(PemUtil.loadPrivateKey(new FileInputStream(new File(weChatProperties.getPrivateKeyFilePath()))));
            signature.update(message);
            String packageSign = Base64.getEncoder().encodeToString(signature.sign());

            //构造数据给微信小程序，用于调起微信支付
            JSONObject jo = new JSONObject();
            jo.put("timeStamp", timeStamp);
            jo.put("nonceStr", nonceStr);
            jo.put("package", "prepay_id=" + prepayId);
            jo.put("signType", "RSA");
            jo.put("paySign", packageSign);

            return jo;
        }
        return jsonObject;
    }

    /**
     * 申请退款
     *
     * @param outTradeNo    商户订单号
     * @param outRefundNo   商户退款单号
     * @param refund        退款金额
     * @param total         原订单金额
     * @return
     */
    public String refund(String outTradeNo, String outRefundNo, BigDecimal refund, BigDecimal total) throws Exception {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("out_trade_no", outTradeNo);
        jsonObject.put("out_refund_no", outRefundNo);

        JSONObject amount = new JSONObject();
        amount.put("refund", refund.multiply(new BigDecimal(100)).setScale(2, BigDecimal.ROUND_HALF_UP).intValue());
        amount.put("total", total.multiply(new BigDecimal(100)).setScale(2, BigDecimal.ROUND_HALF_UP).intValue());
        amount.put("currency", "CNY");

        jsonObject.put("amount", amount);
        jsonObject.put("notify_url", weChatProperties.getRefundNotifyUrl());

        String body = jsonObject.toJSONString();

        //调用申请退款接口
        return post(REFUNDS, body);
    }
}

Controller层

    /**
     * 订单支付
     *
     * @param ordersPaymentDTO
     * @return
     */
    @PutMapping("/payment")
    @ApiOperation("订单支付")
    public Result<OrderPaymentVO> payment(@RequestBody OrdersPaymentDTO ordersPaymentDTO) throws Exception {
        log.info("订单支付：{}", ordersPaymentDTO);
        OrderPaymentVO orderPaymentVO = orderService.payment(ordersPaymentDTO);
        log.info("生成预支付交易单：{}", orderPaymentVO);
        return Result.success(orderPaymentVO);
    }

PayNotifyController.java

package com.sky.controller.notify;

import com.alibaba.druid.support.json.JSONUtils;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.sky.annotation.IgnoreToken;
import com.sky.properties.WeChatProperties;
import com.sky.service.OrderService;
import com.wechat.pay.contrib.apache.httpclient.util.AesUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.entity.ContentType;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;

/**
 * 支付回调相关接口
 */
@RestController
@RequestMapping("/notify")
@Slf4j
public class PayNotifyController {
    @Autowired
    private OrderService orderService;
    @Autowired
    private WeChatProperties weChatProperties;

    /**
     * 支付成功回调
     *
     * @param request
     */
    @RequestMapping("/paySuccess")
    public void paySuccessNotify(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //读取数据
        String body = readData(request);
        log.info("支付成功回调：{}", body);

        //数据解密
        String plainText = decryptData(body);
        log.info("解密后的文本：{}", plainText);

        JSONObject jsonObject = JSON.parseObject(plainText);
        String outTradeNo = jsonObject.getString("out_trade_no");//商户平台订单号
        String transactionId = jsonObject.getString("transaction_id");//微信支付交易号

        log.info("商户平台订单号：{}", outTradeNo);
        log.info("微信支付交易号：{}", transactionId);

        //业务处理，修改订单状态、来单提醒
        orderService.paySuccess(outTradeNo);

        //给微信响应
        responseToWeixin(response);
    }

    /**
     * 读取数据
     *
     * @param request
     * @return
     * @throws Exception
     */
    private String readData(HttpServletRequest request) throws Exception {
        BufferedReader reader = request.getReader();
        StringBuilder result = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            if (result.length() > 0) {
                result.append("\n");
            }
            result.append(line);
        }
        return result.toString();
    }

    /**
     * 数据解密
     *
     * @param body
     * @return
     * @throws Exception
     */
    private String decryptData(String body) throws Exception {
        JSONObject resultObject = JSON.parseObject(body);
        JSONObject resource = resultObject.getJSONObject("resource");
        String ciphertext = resource.getString("ciphertext");
        String nonce = resource.getString("nonce");
        String associatedData = resource.getString("associated_data");

        AesUtil aesUtil = new AesUtil(weChatProperties.getApiV3Key().getBytes(StandardCharsets.UTF_8));
        //密文解密
        String plainText = aesUtil.decryptToString(associatedData.getBytes(StandardCharsets.UTF_8),
                nonce.getBytes(StandardCharsets.UTF_8),
                ciphertext);

        return plainText;
    }

    /**
     * 给微信响应
     * @param response
     */
    private void responseToWeixin(HttpServletResponse response) throws Exception{
        response.setStatus(200);
        HashMap<Object, Object> map = new HashMap<>();
        map.put("code", "SUCCESS");
        map.put("message", "SUCCESS");
        response.setHeader("Content-type", ContentType.APPLICATION_JSON.toString());
        response.getOutputStream().write(JSONUtils.toJSONString(map).getBytes(StandardCharsets.UTF_8));
        response.flushBuffer();
    }
}