并发请求(对多个请求进行合并操作)

  int totalSize = 100;
  int pageSize = 10;
  int totalPage = getTotalPage(totalSize, pageSize);
  ExecutorService executor = Executors.newFixedThreadPool(totalPage);
  long startTime = System.currentTimeMillis();
  try {
      List<CompletableFuture<String>> list = new ArrayList<CompletableFuture<String>>();
      for (int i = 0; i < totalPage; i++) {
          QueryRequest req = new QueryRequest(i, pageSize);
          list.add(CompletableFuture.supplyAsync(() -> {
              return QueryService.query(req);
          }, executor));
      }

      CompletableFuture.allOf(list.toArray(new CompletableFuture[] {})).join();
      StringBuilder sb = new StringBuilder();
      for (CompletableFuture<String> ft : list) {
          String result = ft.get(10, TimeUnit.SECONDS); // 获取结果等待10s超时
          sb.append(result);
      }

      System.err.println("main thread end====>");
      System.err.println(sb.toString());
  } catch (Exception e) {
      e.printStackTrace();
  }
  executor.shutdown();
  System.err.println(System.currentTimeMillis() - startTime);