先推荐3篇文章，讲解延迟队列的实现原理：

基于redis的延迟队列

redis的分布式延迟队列

redission延迟队列的使用

redission官方文档

 

 

代码实现：

@Service
public class KafkaServiceImpl implements KafkaService, InitializingBean {
    private static final Logger LOGGER = LoggerFactory.getLogger(KafkaServiceImpl.class);

    @Resource
    private KafkaTemplate<String, String> stringKafkaTemplate;
    @Resource
    private RedissonClient redissonClient;
    private RBlockingDeque<String> rBlockingDeque;
    private RDelayedQueue<String> rDelayedQueue;
    
    @Override
    public void send(String topic,String key,String jsonObject) {
        stringKafkaTemplate.send(new ProducerRecord<>(topic,key, jsonObject));
        LOGGER.info("send to topic[{}], key[{}], jsonObject[{}]",topic, key, jsonObject);
    }

    @Override
    public void delaySend(String topic, String key, String jsonObject, Long delay, TimeUnit timeUnit) {
        KafkaInfo kafkaInfo = new KafkaInfo();
        kafkaInfo.setTopic(topic);
        kafkaInfo.setKey(key);
        kafkaInfo.setJsonObject(jsonObject);
        this.rDelayedQueue.offer(JSON.toJSONString(kafkaInfo), delay, timeUnit);
        LOGGER.info("send delay [{}], timeUnit[{}] to topic[{}], key[{}], jsonObject[{}]",delay , timeUnit, topic, key,
                jsonObject);
    }

    @Override
    public void afterPropertiesSet() {
        this.rBlockingDeque = redissonClient.getBlockingDeque(KAFKA_DELAY_QUEUE);
        if (this.rBlockingDeque == null) {
            return;
        }
        this.rDelayedQueue = redissonClient.getDelayedQueue(rBlockingDeque);
        if (this.rDelayedQueue == null) {
            return;
        }
        this.startConsumerDelayQueue();
    }

    private static class KafkaInfo implements Serializable {
        private static final long serialVersionUID = -5517223779255526862L;

        private String topic;
        private String key;
        private String jsonObject;

        public String getTopic() {
            return topic;
        }

        public void setTopic(String topic) {
            this.topic = topic;
        }

        public String getKey() {
            return key;
        }

        public void setKey(String key) {
            this.key = key;
        }

        public String getJsonObject() {
            return jsonObject;
        }

        public void setJsonObject(String jsonObject) {
            this.jsonObject = jsonObject;
        }
    }

    private void startConsumerDelayQueue() {

        Thread thread = new Thread(() -> {
            while (true) {
                try {
                    String jsonObject = this.rBlockingDeque.take();
                    LOGGER.info("--> 延迟队列获取数据:{}",jsonObject);
                    KafkaInfo kafkaInfo = JSON.parseObject(jsonObject, KafkaInfo.class);
                    this.send(kafkaInfo.getTopic(), kafkaInfo.getKey(), kafkaInfo.getJsonObject());
                } catch (InterruptedException e) {
                    LOGGER.error("延迟队列获取数据异常....");
                }
            }
        });
        thread.setDaemon(true);
        thread.start();
    }
}

注意：

放入队列是使用的RDelayedQueue，获取队列是使用RQueue而不是RDelayedQueue。