Java future : How to unblock Main thread while executing Aysnc call

Question

当我使用 ExecutorService 进行异步调用时，它返回 Future 对象。根据它返回的 boolean 值，我必须记录异步调用的状态。

但是当我尝试从 future 对象调用方法 get 方法时，它会阻塞主线程执行。

是否可以解除阻塞主线程执行？

public class FutureExample {

    static HystrixCommand<Boolean> hystrixCommand;

    public FutureExample(HystrixCommand<Boolean> hystrixCommand){
        FutureExample.hystrixCommand = hystrixCommand;
    }

    public static void main(String[] args) throws InterruptedException, ExecutionException {


        Boolean something = asyncCall();

        if(something) {
            System.out.println("Future task is done");
        }

        System.out.println("Don't wait for async call");

    }

    private static Boolean asyncCall() throws InterruptedException, ExecutionException {

        Future<Boolean> response = hystrixCommand.queue(); // Aysnc Call to remote server

        return response.get(); //this is blocking main thread
    }

}

Answer 1

futures 的好处是能够释放线程直到答案到达。所以我建议你使用 Future 实现，比如 CompletableFuture:

final ExecutorService executorService = Executors.newFixedThreadPool(10);

CompletableFuture.supplyAsync(() -> {
    try {
        return hystrixCommand.queue();
    } catch (Exception e) {
        return false;
    }
}, executorService);

这将在另一个线程上工作，当那个 future 结束时它就会完成。