CompletionService 使用小结

public static void main(String[] args) throws ExecutionException, InterruptedException {
        //构建线程池
        ExecutorService executorService = Executors.newFixedThreadPool(2);
        FutureTask<Integer> futureTask1 = (FutureTask<Integer>) executorService.submit(()->doTask1());
        FutureTask<Integer> futureTask2 = (FutureTask<Integer>) executorService.submit(()->doTask2());
        //    获取电结果并异步保存
        executorService.execute(()->save(futureTask1.get()));
        //    获取结果并异步保存
        executorService.execute(()->save(futureTask2.get());
    }

 public static void main(String[] args) {
        // 创建线程池
        ExecutorService executor = Executors.newFixedThreadPool(3);
        // 创建CompletionService
        CompletionService<Integer> cs = new ExecutorCompletionService<>(executor);
        // 用于保存Future对象
        List<Future<Integer>> futures = new ArrayList<>(3);
        //提交异步任务，并保存future到futures
        futures.add(cs.submit(()->doTask1()));
        futures.add(cs.submit(()->doTask2()));
        futures.add(cs.submit(()->doTask3()));
        // 获取最快返回的任务执行结果
        Integer r = 0;
        try {
            // 只要有一个成功返回，则break
            for (int i = 0; i < 3; ++i) {
                r = cs.take().get();
                //简单地通过判空来检查是否成功返回
                if (r != null) {
                    break;
                }
            }
        } finally {
            //取消所有任务
            for(Future<Integer> f : futures)
                f.cancel(true);
        }
        // 返回结果
    }