批量执行异步任务CompletionService

批量执行异步任务CompletionService

核心思想，就是将异步结果放入到阻塞队列中，然后再消费队列，实现异步任务批量执行
接口方法说明

Future<V> submit(Callable<V> task);
Future<V> submit(Runnable task, V result);
Future<V> take() 
  throws InterruptedException // 阻塞式调用;
Future<V> poll();
Future<V> poll(long timeout, TimeUnit unit) 
  throws InterruptedException;

public static void test() throws InterruptedException, ExecutionException {
        ExecutorService executor = Executors.newFixedThreadPool(3);
        CompletionService<Integer> cs = new ExecutorCompletionService<Integer>(executor);
        cs.submit(() -> getPriceByS1());
        cs.submit(() -> getPriceByS2());
        cs.submit(() -> getPriceByS3());
        for (int i = 0; i < 3; i++) {
            Integer r = cs.take().get();
            executor.execute( () -> System.out.println("save:" + r));
        }
}

public static Integer getPriceByS1(){
        return 1;
}
public static Integer getPriceByS2(){
        return 2;
}
public static Integer getPriceByS3(){
        return 3;
}