java中延时队列实例

package com.example.demo;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

public class DeQueueTest {


    public static final Logger logger = LoggerFactory.getLogger(DeQueueTest.class);

    public static final int DELAY_PERIOD_SECONDS = 10;    // 延时10秒

    private final static DelayQueue<DelayedElement> delayQueue = new DelayQueue<DelayedElement>();

    /**
     * 以秒为单位计算耗时
     */
    static class DelayedElement implements Delayed {

        // 到期时间
        public long expireTime;
        public String name;

        public DelayedElement(String name){
            this.name = name;
            this.expireTime = (System.currentTimeMillis() / 1000) + DELAY_PERIOD_SECONDS;
        }

        @Override
        public int compareTo(Delayed o) {
            if(this.expireTime < ((DelayedElement)o).expireTime) return -1;
            else if(this.expireTime > ((DelayedElement)o).expireTime)return 1;
            else return 0;
        }

        public void reset() {
            this.expireTime = (System.currentTimeMillis() / 1000) + DELAY_PERIOD_SECONDS;
        }

        // 这边返回的值为0了，就表示到期了
        @Override
        public long getDelay(TimeUnit unit) {
            long r = unit.convert(expireTime - (System.currentTimeMillis() / 1000), TimeUnit.SECONDS);
            return r;
        }

        public String getName() {
            return name;
        }
    }
    


    public static void main(String[] args) throws InterruptedException {
        delayQueue.offer(new DelayedElement("a1"));
        TimeUnit.SECONDS.sleep(3);
        delayQueue.offer(new DelayedElement("a2"));
        TimeUnit.SECONDS.sleep(1);
        delayQueue.offer(new DelayedElement("a3"));
        TimeUnit.SECONDS.sleep(2);
        delayQueue.offer(new DelayedElement("a4"));
        TimeUnit.SECONDS.sleep(3);
        delayQueue.offer(new DelayedElement("a5"));


        while(true) {
            DelayedElement element = delayQueue.poll();
            if (element != null) {
                logger.warn(element.getName());

                // 重新加入
                element.reset();
                delayQueue.offer(element);
            }
            Thread.sleep(100);
        }
    }

}

按时间循环打印输出部分

09:58:18.033 [main] WARN com.example.demo.DeQueueTest - a1
09:58:21.098 [main] WARN com.example.demo.DeQueueTest - a2
09:58:22.082 [main] WARN com.example.demo.DeQueueTest - a3
09:58:24.042 [main] WARN com.example.demo.DeQueueTest - a4
09:58:27.086 [main] WARN com.example.demo.DeQueueTest - a5
09:58:28.062 [main] WARN com.example.demo.DeQueueTest - a1
09:58:31.024 [main] WARN com.example.demo.DeQueueTest - a2
09:58:32.005 [main] WARN com.example.demo.DeQueueTest - a3
09:58:34.089 [main] WARN com.example.demo.DeQueueTest - a4