springboot CompletableFuture并行计算及使用方法

CompletableFuture<String> a1 = CompletableFuture.supplyAsync(() -> {
      try {
          Thread.sleep(1000);
      } catch (InterruptedException e) {
          throw new RuntimeException(e);
      }
      return "Hello World";
  });
  CompletableFuture<String> a2 = CompletableFuture.supplyAsync(() -> {
      try {
          Thread.sleep(2000);
      } catch (InterruptedException e) {
          throw new RuntimeException(e);
      }
      return "Hello World";
  });
  CompletableFuture<String> a3 = CompletableFuture.supplyAsync(() -> {
      try {
          Thread.sleep(3000);
      } catch (InterruptedException e) {
          throw new RuntimeException(e);
      }
      return "Hello World";
  });
  // 这块最后是并行计算时间为3秒
  CompletableFuture.allOf(a1, a2, a3).join();
  String result = a1.get() + " | " + a2.get() + " | " + a3.get();

@Service
@EnableAsync
public class ParallelTaskService {
    @Async
    public CompletableFuture<String> task1() {
        // 模拟一个耗时操作
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return CompletableFuture.completedFuture("Task 1 completed");
    }
    @Async
    public CompletableFuture<String> task2() {
        // 模拟另一个耗时操作
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return CompletableFuture.completedFuture("Task 2 completed");
    }
}
// 并行计算时，响应时间是2和3秒之中最大值，即3秒
@GetMapping("/hello-world2")
public CompletableFuture<String> helloWorld2() {
    CompletableFuture<String> task1Result = parallelTaskService.task1();
    CompletableFuture<String> task2Result = parallelTaskService.task2();
    // 等待所有任务都完成
    CompletableFuture<Void> allOf = CompletableFuture.allOf(task1Result, task2Result);
    // 处理所有任务完成后的逻辑
    return allOf.thenApply(voidResult -> {
        String result = task1Result.join() + " | " + task2Result.join();
        return result;
    });
}