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【Java】DelayQueue

backend 2025/7/27 19:05:26

一，概述

本文简单介绍下延迟队列，顾名思义，加入队列的元素具备延时出队的特征，在诸如延迟消息时可简单使用，本文笔者以学习心态简单介绍下此数据结构。

DelayQueue实现类图如下

DelayQueue实现Queue接口，内部保存一个优先级队列，新加入队列的元素必须实现Delay接口，实现getDelay和compareTo方法，以满足优先级队列排序，以及出队延迟计算。

二，实例

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;public class DelayQueueMain {public static void main(String[] args) throws InterruptedException {DelayQueue<Message> queue = new DelayQueue<>();//创建一个消费者线程new Thread(() -> {try {System.out.println("Consumer Thread Create.");while (true) {Message message = queue.take();message.action.run();}} catch (InterruptedException e) {throw new RuntimeException(e);}}).start();//生产者for (int i = 0; i < 10; i++) {Message message = new Message((10 - i) * 200, i);queue.add(message);Thread.sleep(100);}}private static class Message implements Delayed {private final long createTime;private final long delayMs;private final long id;private final Runnable action = new Runnable() {@Overridepublic void run() {//简单demo，打印id即可System.out.println("invoke Message Id=" + id + ", DelayMs=" + delayMs);}};public Message(long delayMs, long id) {this.id = id;this.delayMs = delayMs;this.createTime = System.currentTimeMillis();}@Overridepublic long getDelay(TimeUnit unit) {return this.createTime + this.delayMs - System.currentTimeMillis();}@Overridepublic int compareTo(Delayed o) {long selfDelay = getDelay(TimeUnit.MILLISECONDS);long otherDelay = o.getDelay(TimeUnit.MILLISECONDS);if (selfDelay == otherDelay) {return 0;}return selfDelay > otherDelay ? 1 : -1;}}
}

输出如下