Java异步编程之Callbacks与Futures模型详解

public class CallbackModel implements Callback, Runnable {
    @Override
    public void invoke() {
        System.out.println("这是异步回调的结果");
    }
    @Override
    public void run() {
        try {
            System.out.println(Thread.currentThread().getName() + "::异步线程任务开始");
            Thread.sleep(1000);
            System.out.println(Thread.currentThread().getName() + "::异步线程任务结束");
            invoke();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        System.out.println(Thread.currentThread().getName() + "::主线程开始");
        new Thread(new CallbackModel(), "线程一").start();
        System.out.println(Thread.currentThread().getName() + "::主线程结束");
    }
}
interface Callback {
    void invoke();
}

public class FutureModel {

    static class FutureTask implements Callable {

        @Override
        public Object call()  {
            try {
                System.out.println(Thread.currentThread().getName() + "::异步线程任务开始");
                Thread.sleep(4000);
                System.out.println(Thread.currentThread().getName() + "::异步线程任务结束");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "1234";
        }
    }


    public static void main(String[] args) {
        ExecutorService pool = Executors.newSingleThreadExecutor();
        Future<String> submit = pool.submit(new FutureTask());
        try {
            System.out.println(Thread.currentThread().getName() + "返回的结果::" + submit.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }finally {
            pool.shutdown();
        }
    }
}

/**
*异步计算的结果
*/
public interface Future<V> {

    /**
     * 尝试取消任务，有可能失败
     */
    boolean cancel(boolean mayInterruptIfRunning);

    /**
     * 判断是否取消
     *
     * @return {@code true} if this task was cancelled before it completed
     */
    boolean isCancelled();

    /**
     *  * 判断是否完成
     *
     * @return {@code true} if this task completed
     */
    boolean isDone();

    /**
     * 等待直至获取结果
     */
    V get() throws InterruptedException, ExecutionException;

    /**
     * 等待指定的时间获取结果，否则抛出异常
     */
    V get(long timeout, TimeUnit unit)
        throws InterruptedException, ExecutionException, TimeoutException;
}