从实现到原理，我总结了11种延迟任务的实现方式（下篇）

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
    <version>2.2.5.RELEASE</version>
</dependency>

spring:
  redis:
    host: 192.168.200.144
    port: 6379

@Configuration
public class RedisConfiguration {

    @Bean
    public RedisMessageListenerContainer redisMessageListenerContainer(RedisConnectionFactory connectionFactory){
        RedisMessageListenerContainer redisMessageListenerContainer = new RedisMessageListenerContainer();
        redisMessageListenerContainer.setConnectionFactory(connectionFactory);
        return redisMessageListenerContainer;
    }

    @Bean
    public KeyExpirationEventMessageListener redisKeyExpirationListener(RedisMessageListenerContainer redisMessageListenerContainer){
        return new KeyExpirationEventMessageListener(redisMessageListenerContainer);
    }

}

@Component
public class MyRedisKeyExpiredEventListener implements ApplicationListener<RedisKeyExpiredEvent> {

    @Override
    public void onApplicationEvent(RedisKeyExpiredEvent event){
        byte[] body = event.getSource();
        System.out.println("获取到延迟消息：" + new String(body));
    }

}

set sanyou task 

expire sanyou 5

<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson</artifactId>
    <version>3.13.1</version>
</dependency>

@Component
@Slf4j
public class RedissonDelayQueue {

    private RedissonClient redissonClient;

    private RDelayedQueue<String> delayQueue;
    private RBlockingQueue<String> blockingQueue;

    @PostConstruct
    public void init(){
        initDelayQueue();
        startDelayQueueConsumer();
    }

    private void initDelayQueue(){
        Config config = new Config();
        SingleServerConfig serverConfig = config.useSingleServer();
        serverConfig.setAddress("redis://localhost:6379");
        redissonClient = Redisson.create(config);

        blockingQueue = redissonClient.getBlockingQueue("SANYOU");
        delayQueue = redissonClient.getDelayedQueue(blockingQueue);
    }

    private void startDelayQueueConsumer(){
        new Thread(() -> {
            while (true) {
                try {
                    String task = blockingQueue.take();
                    log.info("接收到延迟任务:{}", task);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "SANYOU-Consumer").start();
    }

    public void offerTask(String task, long seconds){
        log.info("添加延迟任务:{} 延迟时间:{}s", task, seconds);
        delayQueue.offer(task, seconds, TimeUnit.SECONDS);
    }

}

@RestController
public class RedissonDelayQueueController {

    @Resource
    private RedissonDelayQueue redissonDelayQueue;

    @GetMapping("/add")
    public void addTask(@RequestParam("task"){
        redissonDelayQueue.offerTask(task, 5);
    }

}

@Slf4j
public class NettyHashedWheelTimerDemo {

    public static void main(String[] args){
        HashedWheelTimer timer = new HashedWheelTimer(100, TimeUnit.MILLISECONDS, 8);
        timer.start();

        log.info("提交延迟任务");
        timer.newTimeout(timeout -> log.info("执行延迟任务"), 5, TimeUnit.SECONDS);
    }

}

@Slf4j
public class SystemTimerDemo {

    public static void main(String[] args){
        SystemTimer systemTimer = new SystemTimer();
        systemTimer.start();

        log.info("提交延迟任务");
        systemTimer.addTask(new TimerTask(() -> log.info("执行延迟任务"), 5000));
    }

}

<dependency>
    <groupId>org.quartz-scheduler</groupId>
    <artifactId>quartz</artifactId>
    <version>2.3.2</version>
</dependency>

@Slf4j
public class SanYouJob implements Job {
    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        JobDetail jobDetail = context.getJobDetail();
        JobDataMap jobDataMap = jobDetail.getJobDataMap();
        log.info("获取到延迟任务:{}", jobDataMap.get("delayTask"));
    }
}

public class QuartzDemo {

    public static void main(String[] args) throws SchedulerException, InterruptedException {
        // 1.创建Scheduler的工厂
        SchedulerFactory sf = new StdSchedulerFactory();
        // 2.从工厂中获取调度器实例
        Scheduler scheduler = sf.getScheduler();

        // 6.启动 调度器
        scheduler.start();

        // 3.创建JobDetail，Job类型就是上面说的SanYouJob
        JobDetail jb = JobBuilder.newJob(SanYouJob.class)
                .usingJobData("delayTask", "这是一个延迟任务")
                .build();

        // 4.创建Trigger
        Trigger t = TriggerBuilder.newTrigger()
                //任务的触发时间就是延迟任务到的延迟时间
                .startAt(DateUtil.offsetSecond(new Date(), 5))
                .build();

        // 5.注册任务和定时器
        log.info("提交延迟任务");
        scheduler.scheduleJob(jb, t);
    }
}

@Slf4j
public class PollingTaskDemo {

    private static final List<DelayTask> DELAY_TASK_LIST = new CopyOnWriteArrayList<>();

    public static void main(String[] args){
        new Thread(() -> {
            while (true) {
                try {
                    for (DelayTask delayTask : DELAY_TASK_LIST) {
                        if (delayTask.triggerTime <= System.currentTimeMillis()) {
                            log.info("处理延迟任务:{}", delayTask.taskContent);
                            DELAY_TASK_LIST.remove(delayTask);
                        }
                    }
                    TimeUnit.MILLISECONDS.sleep(100);
                } catch (Exception e) {
                }
            }
        }).start();

        log.info("提交延迟任务");
        DELAY_TASK_LIST.add(new DelayTask("三友的java日记", 5L));
    }

    @Getter
    @Setter
    public static class DelayTask {

        private final String taskContent;

        private final Long triggerTime;

        public DelayTask(String taskContent, Long delayTime){
            this.taskContent = taskContent;
            this.triggerTime = System.currentTimeMillis() + delayTime * 1000;
        }
    }

}