java - Spring Boot 在 Controller 内执行并行方法

Question

我正在尝试在 Controller 内执行一些并行方法，但我在返回类型方面遇到了一些问题。

我有 4 个方法，每个方法都返回一个列表。我需要以并行方式执行这些方法，然后获取每个返回的列表，并将所有这些列表放入映射中，并从 Controller 返回该映射。 代码如下:

Callable<List> callable1 = new Callable<List>()
           {
              @Override
              public List call() throws Exception
              {
                List<SearchResultAutovit> lista;
                lista = scrapperAutovit.searchAutovit(marcaId, modelId, pretDeLa, pretPanaLa, anFabrDeLa, anFabrPanaLa,
                        orasParam);
                 return lista;
              }
           };

           Callable<List> callable2 = new Callable<List>()
           {
              @Override
              public List call() throws Exception
              {
                  List<SearchResultOlx> listaOlx;
                String marcaOlx = marcaId.toLowerCase();
                String modelOlx = modelId.toLowerCase();
                String orasOlx = orasParam.toLowerCase();
                listaOlx = scrapperOlx.searchOlx(marcaOlx, modelOlx, pretDeLa, pretPanaLa, anFabrDeLa, anFabrPanaLa, orasOlx);
                 return listaOlx;
              }
           };

           Callable<List> callable3 = new Callable<List>()
           {
              @Override
              public List call() throws Exception
              {
                List<SearchResultPubli24> listaPubli24;
                String orasPubli24 = orasParam.toLowerCase();
                listaPubli24 = scrapperPubli24.searchPubli24(marcaId, modelId, orasPubli24, anFabrDeLa, anFabrPanaLa, pretDeLa, pretPanaLa);
                 return listaPubli24;
              }
           };

           Callable<List> callable4 = new Callable<List>()
           {
              @Override
              public List call() throws Exception
              {
                 List<SearchResultAutoUncle> listaAutoUncle;
                listaAutoUncle = scrapperAutoUncle.searchAutoUncle(marcaId, modelId, pretDeLa, pretPanaLa, anFabrDeLa, anFabrPanaLa, orasParam);
                 return listaAutoUncle;
              }
           };

           //add to a list
           List<Callable<List>> taskList = new ArrayList<Callable<List>>();
           taskList.add(callable1);
           taskList.add(callable2);
           taskList.add(callable3);
           taskList.add(callable4);

           ExecutorService executor = Executors.newFixedThreadPool(3);
           executor.invokeAll(taskList);

           Map<String,List<?>> listOfWebsites = new HashMap<>();
            listOfWebsites.put("listaAutovit", (List<?>) taskList.get(0));
            listOfWebsites.put("listaOlx", (List<?>) taskList.get(1));
            listOfWebsites.put("listaPubli24", (List<?>) taskList.get(2));
            listOfWebsites.put("listaAutoUncle", (List<?>) taskList.get(3));

        return listOfWebsites;

我很确定我没有做正确的事情，因为它抛出java.lang.ClassCastException:com.test.controller.HomeController$1与java.util.List不兼容 我猜问题是名为 listOfWebsites 的 map ，它应该具有可调用对象的返回类型，一些列表:(

Answer 1

首先，更改可调用对象的类型以避免强制转换:

    Callable<List<?>> callable1 = new Callable<List>(){...}

然后，你必须等待并行计算的结果。您不需要创建 CompletableFuture，因为您可以直接从 ExecutorService 获取 Future:

    ExecutorService executor = Executors.newFixedThreadPool(3);
    Future<List<?>> future1 = executor.submit(callable1);
    Future<List<?>> future2 = executor.submit(callable2);
    Future<List<?>> future3 = executor.submit(callable3);
    Future<List<?>> future4 = executor.submit(callable4);

    Map<String,List<?>> listOfWebsites = new HashMap<>();
    listOfWebsites.put("listaAutovit", future1.get());
    listOfWebsites.put("listaOlx", future2.get());
    listOfWebsites.put("listaPubli24", future3.get());
    listOfWebsites.put("listaAutoUncle", future4.get());

    return listOfWebsites;

就是这样。