public static void main(String[] args) {
		ExecutorService threadPool = Executors.newSingleThreadExecutor();
		Future<String> future = threadPool.submit(new Callable<String>() {
			@Override
			public String call() throws Exception {
				Thread.sleep(2000);
				return "Hello";
			}
		});
		System.out.println("Waiting result!");
		try {
			System.out.println("The result is " + future.get());
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
		System.out.println("==============");

		//下面模拟返回多个数值
		ExecutorService threadPool2 = Executors.newFixedThreadPool(10);
		CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(
				threadPool2);
		for (int i = 1; i < 10; i++) {
			final int j = i;
			completionService.submit(new Callable<Integer>() {
				@Override
				public Integer call() throws Exception {
					Thread.sleep(new Random().nextInt(5000));
					return j;
				}
			});
		}
		for(int i=0; i<10; i++) {
			try {
				System.out.println(completionService.take().get());
			} catch (InterruptedException e) {
				e.printStackTrace();
			} catch (ExecutionException e) {
				e.printStackTrace();
			}
		}
		System.out.println("============");
	}