DelayQueue测试

DelayQueue是用于可被延迟操作的队列,在ScheduledThreadPoolExecutor中使用..经常用来设计"定时消费"的队列,即提供了对queue中成员按照"过期"时间排序能力,从queue中获取的成员必将是离超时最近的;此外DelayQueue是支持并发的,它内部实现非常简单:ReentrantLock + PriorityQueue;

如下为自己测试类.

 

public class DelayQueueTest {
/**
 * @param args
 */
	public static void main(String[] args) {
		DelayQueue<DelayedItem> queue = new DelayQueue<DelayedItem>();
		for(int i = 0; i<5; i++){
			queue.add(new DelayedItem(System.currentTimeMillis() - i * 1000));
		}
		DelayedItem item = null;
		while((item = queue.peek()) != null){
			System.out.println("...." + item.getTime());
			if(item.getDelay(TimeUnit.MILLISECONDS) <= 0){
				queue.poll();
			}
		}
		System.out.println("End,queue size is :" + queue.size());
	}

	public static class DelayedItem implements Delayed{
		private long time;
		DelayedItem(long time){
			this.time = time;
		}
		public long getTime() {
			return time;
		}
		@Override
		public long getDelay(TimeUnit unit) {
			return unit.convert(time - System.currentTimeMillis(),TimeUnit.MILLISECONDS);
		}
		@Override
		public int compareTo(Delayed o) {
			if(o instanceof DelayedItem){
				DelayedItem di = (DelayedItem)o;
				if(time > di.getTime()){
					return 1;
				}else if(time == di.getTime()){
					return 0;
				}else{
					return -1;
				}
			}
			throw new RuntimeException("State Error!");
		}
	}
}