Spring Boot 集成微信支付 V3 版，关键配置与下单代码详解

<dependency>
    <groupId>com.wechat.pay.java</groupId>
    <artifactId>service</artifactId>
    <version>0.2.15</version>
</dependency>

@Configuration
public class WeChatPayConfig {

    @Value("${wechat.mch-id}")
    private String mchId;

    @Value("${wechat.mch-serial-no}")
    private String merchantSerialNumber;

    @Value("${wechat.api-v3-key}")
    private String apiV3Key;

    @Value("${wechat.private-key-path}")
    private String privateKeyPath;

    @Bean
    public Config weChatPayConfig() throws IOException {
        // 读取本地私钥文件
        File privateKeyFile = new File(privateKeyPath);
        String privateKeyContent = Files.toString(privateKeyFile, StandardCharsets.UTF_8);

        // 构建 RSA 公钥模式配置（推荐新商户使用）
        return new RSAPublicKeyConfig.Builder()
                .merchantId(mchId)
                .privateKey(privateKeyContent)
                .merchantSerialNumber(merchantSerialNumber)
                .apiV3Key(apiV3Key)
                .build();
    }
}

@Service
public class PaymentService {

    @Autowired
    private Config config;

    public PrepayWithRequestPaymentResponse createPrepayOrder(String openId, String orderNo, int totalAmountCents, String description) {
        // 构建服务实例
        JsapiServiceExtension service = new JsapiServiceExtension.Builder()
                .config(config)
                .build();

        // 组装请求参数
        PrepayRequest request = new PrepayRequest();
        request.setAppid("你的小程序 AppID");
        request.setMchid(config.getMerchantId());
        request.setDescription(description);
        request.setOutTradeNo(orderNo);
        request.setNotifyUrl("https://your-domain.com/api/pay/notify");

        // 设置金额（单位：分）
        Amount amount = new Amount();
        amount.setTotal(totalAmountCents);
        request.setAmount(amount);

        // 设置支付者信息
        Payer payer = new Payer();
        payer.setOpenid(openId);
        request.setPayer(payer);

        try {
            // 调用下单并获取前端所需参数
            return service.prepayWithRequestPayment(request);
        } catch (ServiceException e) {
            // 处理业务异常，如重复下单、余额不足等
            throw new RuntimeException("微信支付下单失败：" + e.getMessage(), e);
        }
    }
}

@RestController
@RequestMapping("/api/pay")
public class PayNotifyController {

    @Autowired
    private Config config;

    @PostMapping("/notify")
    public String handleNotify(HttpServletRequest request) throws IOException {
        String body = IoUtil.readUtf8(request.getInputStream());
        String serialNumber = request.getHeader("Wechatpay-Serial");
        String timestamp = request.getHeader("Wechatpay-Timestamp");
        String nonce = request.getHeader("Wechatpay-Nonce");
        String signature = request.getHeader("Wechatpay-Signature");

        // 构建解析器
        NotificationParser parser = new NotificationParser(
                new RSAPublicKeyConfig.Builder()
                        .merchantId(config.getMerchantId())
                        .privateKey(config.getPrivateKey()) // 此处需传入私钥用于验签
                        .merchantSerialNumber(config.getMerchantSerialNumber())
                        .apiV3Key(config.getApiV3Key())
                        .build()
        );

        try {
            // 解析并解密数据，泛型指定为 Transaction
            Transaction transaction = parser.parse(
                    new HttpHeaders(serialNumber, timestamp, nonce, signature),
                    body,
                    Transaction.class
            );

            // 业务逻辑处理
            if ("SUCCESS".equals(transaction.getTradeState())) {
                String outTradeNo = transaction.getOutTradeNo();
                // TODO: 根据 outTradeNo 更新本地订单状态为“已支付”
                // 注意：此处需做幂等性检查，防止重复处理
                updateOrderStatus(outTradeNo);
            }

            // 返回成功应答，格式必须严格符合微信要求
            WxPayNotifyResponse response = WxPayNotifyResponse.success("处理成功");
            return JsonUtil.toJson(response);

        } catch (ParseException e) {
            // 验签或解密失败，返回失败应答
            WxPayNotifyResponse response = WxPayNotifyResponse.fail("解析失败");
            return JsonUtil.toJson(response);
        }
    }
    
    private void updateOrderStatus(String orderNo) {
        // 模拟数据库更新逻辑
        System.out.println("订单 " + orderNo + " 支付成功，状态已更新");
    }
}