DelayQueue是BlockingQueue接口的一个实现类之一
这个属于基础性问题,老规矩,我们将从使用场景和代码示例来进行讲解
来,思考片刻,给出你的答案
1,使用场景
- 实现:延迟队列,其中元素只有在其预定时间到达后才可以从队列中取出。
- 场景:适用于延时任务调度,如定时任务、缓存失效处理等。
2,代码示例
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;class DelayedItem implements Delayed {private long delayTime; // 延迟时间private long insertionTime; // 加入队列的时间public DelayedItem(long delay, TimeUnit unit) {this.delayTime = unit.toNanos(delay);this.insertionTime = System.nanoTime();}@Overridepublic long getDelay(TimeUnit unit) {return unit.convert(delayTime - (System.nanoTime() - insertionTime), TimeUnit.NANOSECONDS);}@Overridepublic int compareTo(Delayed o) {if (this == o)return 0;long diff = (getDelay(TimeUnit.NANOSECONDS) - o.getDelay(TimeUnit.NANOSECONDS));return (diff == 0) ? 0 : ((diff < 0) ? -1 : 1);}@Overridepublic String toString() {return "DelayedItem";}
}public class DelayQueueExample {static final DelayQueue<DelayedItem> queue = new DelayQueue<>();public static void main(String[] args) throws InterruptedException {queue.put(new DelayedItem(5, TimeUnit.SECONDS));Thread consumer = new Thread(() -> {try {DelayedItem delayedItem = queue.take(); // 只有延迟时间到了才能取出System.out.println("Consumed after delay: " + delayedItem);} catch (InterruptedException e) {e.printStackTrace();}});consumer.start();// 等待consumer完成consumer.join();}
}
至此,关于BlockingQueue接口的关键实现类也给大伙介绍完毕了
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