微信支付V3 java 支付回调代码

以下是微信支付V3 java支付回调代码示例：

import com.tencent.wework.pay.v3.*;
import com.tencent.wework.pay.v3.transactions.*;
import java.io.*;
import java.time.*;
import java.util.*;
import javax.servlet.http.*;
import org.apache.commons.io.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PaymentCallbackServlet extends HttpServlet {

    private static final Logger logger = LoggerFactory.getLogger(PaymentCallbackServlet.class);

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String requestBody = IOUtils.toString(request.getInputStream(), "UTF-8");
        logger.info("Received payment callback request body: {}", requestBody);

        Map<String, String> headers = new HashMap<>();
        Enumeration<String> headerNames = request.getHeaderNames();
        while (headerNames.hasMoreElements()) {
            String headerName = headerNames.nextElement();
            headers.put(headerName, request.getHeader(headerName));
        }

        String timestamp = headers.get("Wechatpay-Timestamp");
        String nonce = headers.get("Wechatpay-Nonce");
        String signature = headers.get("Wechatpay-Signature");
        String serialNo = headers.get("Wechatpay-Serial");

        String bodyHash = SignUtils.sha256(requestBody);
        String signData = SignUtils.getSignData(timestamp, nonce, bodyHash);
        boolean verifyResult = SignUtils.verifySignature(signature, signData, serialNo);

        if (!verifyResult) {
            logger.error("Payment callback signature verification failed.");
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            return;
        }

        try {
            PaymentNotify notify = JsonUtils.fromJson(requestBody, PaymentNotify.class);
            logger.info("Received payment notify: {}", notify);

            // TODO: 处理支付结果

            response.getWriter().write("SUCCESS");
        } catch (Exception e) {
            logger.error("Failed to handle payment callback.", e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        }
    }
}

其中，`PaymentNotify`是自定义的类，表示支付回调的参数，可以根据实际情况自行定义。`SignUtils`是签名工具类，提供了签名和验签的方法。`JsonUtils`是json工具类，用于将请求体转换为java对象。在`TODO`处需要根据实际情况处理支付结果。最后，返回`SUCCESS`表示处理成功。