  @Test
  public void testCompletableFutureTask() throws InterruptedException, ExecutionException {

    // 开始时间
    long start = System.currentTimeMillis();
    // 开始执行大量的异步任务
    List<String> words = Arrays.asList("F", "T", "S", "Z", "J", "C");
    List<CompletableFuture<List<String>>> completableFutureList =
        words.stream()
            .map(word -> asyncService.completableFutureTask(word))
            .collect(Collectors.toList());
    // CompletableFuture.join（）方法可以获取他们的结果并将结果连接起来
    List<List<String>> results =
        completableFutureList.stream().map(CompletableFuture::join).collect(Collectors.toList());
    // 打印结果以及运行程序运行花费时间
    System.out.println("Elapsed time: " + (System.currentTimeMillis() - start));
    System.out.println(results.toString());
  }