如何发送异步Http Response？

Question

我创建了一个 Rest API，它接受请求并向客户端提供响应。但是我的 API 依赖于第三方服务，它没有给出响应，而是给我的另一个端点回调。为了发送服务，我需要等待收到回调。我怎样才能实现它？

My Rest API 需要发送响应。

@POST
//  @Produces(MediaType.TEXT_XML)
//  @Consumes(MediaType.TEXT_XML)
    public ConnectResponse connectAPI(String connectString, @Context HttpHeaders headers) {
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        for (Entry<String, List<String>> entry : headers.getRequestHeaders().entrySet()) {
            logger.info("Key = " + entry.getKey() + ", Value = " + entry.getValue());
            for (String eachEntry : entry.getValue()) {
                logger.info("eachEntry " + eachEntry);
            }
        }
        logger.info("USSD received " + connectString);
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        logger.info("---------- in connect post request ----------------------");
        ConnectRequest requestObj = new ConnectRequest();
        try {
            if (connectString != null && connectString.startsWith("<")) {
                requestObj = marshallConnectRequest(connectString);
            } else {
                requestObj = convertKeyValueToObject(connectString);
            }

            logger.info("Request is " + requestObj);
        } catch (JAXBException e) {
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error("----------------- Error in UnMarshalling ----------");
            logger.error(e.getMessage(), e);
        }
        ConnectResponse connectResponse = new ConnectResponse();
        connectResponse.setSession(requestObj.getSessionid());
        connectResponse.setText("Hello");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        logger.info("---------- returning response ----------------------");
        return connectResponse;
    }

    public ConnectRequest marshallConnectRequest(String connectString) throws JAXBException {
        JAXBContext jaxbContext = JAXBContext.newInstance(ConnectRequest.class);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        return (ConnectRequest) jaxbUnmarshaller.unmarshal(new StringReader(connectString));
    }

    public ConnectRequest convertKeyValueToObject(String connectString) {
        return new ConnectRequest();
    }

我不想发送简单的响应对象，而是希望在以下 API.

处等待回调命中

@Path("/rest")
public class RESTWebservice {
    /*
     * @Context private MessageContext messageContext;
     */
    final Logger logger = Logger.getLogger(RESTWebservice.class);

    @POST
    @Path("/sendResponse")
    @Produces(MediaType.APPLICATION_JSON)
    @Consumes(MediaType.APPLICATION_JSON)
    public ResponseJSON postQuestionnaire(RequestJSON requestJson) {
    // performing operations
}

通话流程：-

客户端将调用连接API，后者将调用第三方API。
第三方API处理上述调用后会回调postQuestionnaire
connectAPI只有收到postQuestionnaire的回调才会发送response

Answer 1

理想情况下，这应该是您的流程

客户端将调用连接API，后者将调用第三方API。
第三方API处理上述调用后会回调发布问卷。 ---> 这应该使用 Callable 使用执行程序服务的任务在单独的线程中完成。然后您将 Future<ResponseFromPOstQuestionnaire> return 从执行程序服务 submit 调用
连接API只有在收到问卷后的回调。 ---> 一旦你有 Future 对象，你可以通过调用 .get() 来等待（这是阻塞调用）所以它会等待响应到来然后你可以 return 相同的响应或修改回复给客户。

有关如何将可调用任务与执行程序服务一起使用的示例在此处解释 -> https://www.journaldev.com/1090/java-callable-future-example

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