同步包中的定时器

同步包中的定时器

ScheduledExecutorService  利用线程池进行调度任务，内部使用一个DelayedWorkQueue实现，返回ScheduledFuture，而DelayQueue是用优先级队列PriorityQueue实现的一个阻塞队列， 优先队列的比较基准值是时间

  private static class DelayedWorkQueue 

        extends AbstractCollection<Runnable> 

        implements BlockingQueue<Runnable> {

        

        private final DelayQueue<ScheduledFutureTask> dq = new DelayQueue<ScheduledFutureTask>();

}

public class DelayQueue<E extends Delayed> extends AbstractQueue<E>

    implements BlockingQueue<E> {

    private transient final ReentrantLock lock = new ReentrantLock();

    private transient final Condition available = lock.newCondition();

    private final PriorityQueue<E> q = new PriorityQueue<E>();

下面为一个小例:

public class ConcurrentTimer {

public static void main(String[] args) {

new ConcurrentTimer().getScheduledExecutorService();

}

public void getScheduledExecutorService() {

ScheduledExecutorService service = Executors.newScheduledThreadPool(10);

service.scheduleAtFixedRate(new Command(), 1, 1, TimeUnit.SECONDS);

}

public class Command implements Runnable {

public void run() {

System.out.println("Command");

}

}

}