java并发之——DelayQueue 延时队列

package com.delayqueue;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
/*延时队列DelayQueue，没有到期取不出队列内的元素（返回 null）*/
public class DelayedTask implements Delayed,Runnable {

	public final int id;
	private final long delayTime; // 延迟时间
	private final long expire; // 到期时间

	public DelayedTask(int id,long delay) {
		this.id = id;
		this.delayTime = delay;
		expire = System.currentTimeMillis() + delay;
	}

	/**
	 * 剩余时间=到期时间-当前时间
	 */
	public long getDelay(TimeUnit unit) {
		return unit.convert(this.expire - System.currentTimeMillis(),
				TimeUnit.MILLISECONDS);
	}

	/**
	 * 优先队列里面优先级规则
	 */
	public int compareTo(Delayed o) {
		return (int) (this.getDelay(TimeUnit.MILLISECONDS) - o
				.getDelay(TimeUnit.MILLISECONDS));
	}


	public static void main(String[] args) throws InterruptedException {

		DelayQueue delayQueue = new DelayQueue();
		CountDownLatch cdw = new CountDownLatch(5);

		for(int i=0;i<5;i++){
			DelayedTask dTask = new DelayedTask(i, i*1000);
			delayQueue.offer(dTask);
			cdw.countDown();
		}
		
		cdw.await();
		while(!delayQueue.isEmpty()){
			DelayedTask dt= delayQueue.poll();
			Thread t = new Thread(dt, dt==null?"线程":dt.id+"");
			t.start();
		}

		
	}

	public void run() {
		System.out.println(Thread.currentThread()+"run + currenttime "+System.currentTimeMillis());
	}

}

运行效果：

每隔1秒输出一次