Spring Boot：异步请求不返回任何东西

  • Z时代
  • 2024-01-10
  • 分类：问答

：

$('#loaderImage').show();
$http.get('/utilities/longProcess')
    .success(function(data, status, headers, config) {
        console.log('Completed');
        $scope.sampleJSON = data.pmdStructureWrapper;
        $scope.sampleJSONDuplicates = data.pmdDuplicates;
        $scope.$watch('sampleJSON', setTimeout(function() {
            $('.panel-body li').each(function() {
                if ($.trim($(this).text()) === "") {
                    $(this).hide();
                }
            });
        }, 1000));
        $('#loaderImage').hide();
    })
    .error(function(data, status, header, config) {
    });

控制器：

@RequestMapping("/utilities/longProcess")
    public DeferredResult<String> async(HttpServletResponse response, HttpServletRequest request) {
        DeferredResult<String> dr = new DeferredResult<>();
        CompletableFuture.supplyAsync(() -> {
            return callURL(response, request);
        }, ex).thenAccept((String message) -> {
            dr.setResult(message);
        });
        return dr;
    }
private String callURL(HttpServletResponse response, HttpServletRequest request){
    PMDMainWrapper pmdMainWrapper = new PMDMainWrapper();
    Map<String, PMDStructureWrapper> codeReviewByClass = new HashMap<>();
    String partnerURL = this.partnerURL;
    String toolingURL = this.toolingURL;
    Cookie[] cookies = request.getCookies();
    List<PMDStructure> violationStructure = null;
    try {
        violationStructure = metadataLoginUtil.startReviewer(partnerURL, toolingURL, cookies);
    } catch (Exception e) {
        e.printStackTrace();
    }
    PMDStructureWrapper pmdStructureWrapper = null;
    List<PMDStructure> pmdStructureList = null;
    List<PMDStructure> pmdDuplicatesList = new ArrayList<>();
    int size = violationStructure.size();
    long start = System.currentTimeMillis();
    for (int i = 0; i < size; i++) {
        if (codeReviewByClass.containsKey(violationStructure.get(i).getName())) {
            PMDStructureWrapper pmdStructureWrapper1 = codeReviewByClass.get(violationStructure.get(i).getName());
            List<PMDStructure> pmdStructures = pmdStructureWrapper1.getPmdStructures();
            pmdStructures.add(violationStructure.get(i));
            pmdStructureWrapper1.setPmdStructures(pmdStructures);
        } else {
            pmdStructureList = new ArrayList<>();
            pmdStructureList.add(violationStructure.get(i));
            pmdStructureWrapper = new PMDStructureWrapper();
            pmdStructureWrapper.setPmdStructures(pmdStructureList);
            codeReviewByClass.put(violationStructure.get(i).getName(), pmdStructureWrapper);
        }
    }
    long stop = System.currentTimeMillis();
    LOGGER.info("Total Time Taken from PMDController "+  String.valueOf(stop-start));
    if (!codeReviewByClass.isEmpty()) {
        pmdMainWrapper.setPmdStructureWrapper(codeReviewByClass);
        pmdMainWrapper.setPmdDuplicates(pmdDuplicatesList);
        Gson gson = new GsonBuilder().create();
        return gson.toJson(pmdMainWrapper);
    }
    return "";
}

我正在使用异步流程，因为当应用程序托管在heroku中时，将结果返回页面需要大约120秒的时间，但是根据heroku文档，其余api应该在30秒内返回，否则它将终止该过程，

但是仍然在实现上述逻辑之后，仍然看到超时错误。我在javascript中保留了一个控制台日志，console.log('Completed');但是仅当它从callURL方法返回结果（超过120秒才能返回）时才打印该日志。

我要实现的是，当UI发送请求时，它应该继续接收一条消息，指出该消息仍在加载中，以便请求不会超时？

回答：

CompletableFuture.supplyAsync()在不同的线程中运行指定的供应商（ForkJoinThreadPool默认为）。thenAccept()方法仅在上一次执行返回后运行。因此，在您的情况下它不会很快返回，您只是在另一个线程中调用长时间运行的调用。

而是定义一个公共对象，该对象充当缓存（例如HttpSession），并CompletableFuture返回存储在其中的对象。并callURL()仅在缓存为空时执行：

@RequestMapping("/utilities/longProcess")
public CompletableFuture<String> async(HttpServletResponse response, HttpServletRequest request) {
    HttpSession session = request.getSession();
    return CompletableFuture.supplyAsync(() -> session.getAttribute("CACHED_RESULT"))
            .thenComposeAsync(obj -> {
                if (obj == null) {
                    CompletableFuture.supplyAsync(() -> callUrl(request, response))
                            .thenAccept(result -> session.setAttribute("CACHED_RESULT", result));
                    return CompletableFuture.completedFuture("not ready yet");
                }
                return CompletableFuture.completedFuture(obj.toString());
            });

您还可以添加一个时间戳记，以查看上次拨打电话的时间，callUrl()以及拨打callUrl()电话但尚未收到答案时不再打给您的电话。

以上是 Spring Boot：异步请求不返回任何东西 的全部内容， 来源链接： utcz.com/qa/424549.html

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