DelayQueue——延时队列做定时任务

最新推荐文章于 2025-04-01 16:14:16 发布

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本文介绍了一个Java类，实现ItemDelayed，用于在指定时间后执行任务，并讨论了如何通过BroadcastThread使用DelayQueue进行任务调度，同时考虑了断电情况下数据持久化策略。

@Data
public class ItemDelayed implements Delayed {
    private Long id;
    //触发时间
    private long time;
    //内容
    private String body;

    public ItemDelayed(){

    }
    public ItemDelayed(Long id,long time,String body, TimeUnit unit) {
        this.id = id;
        this.body = body;
        this.time = TimeUnit.NANOSECONDS.convert(time, TimeUnit.MILLISECONDS) + System.nanoTime();
    }

    @Override
    public long getDelay(TimeUnit unit) {
        return time - System.currentTimeMillis();
    }

    @Override
    public int compareTo(Delayed o) {
        ItemDelayed item = (ItemDelayed) o;
        long diff = this.time - item.time;
        if (diff <= 0) {
            return -1;
        }else {
            return 1;
        }
    }
}

@Slf4j
public class BroadcastThread implements Runnable{
    private DelayQueue<ItemDelayed> delayQueue;
    @Autowired(required = false)
    private BroadcastMapper broadcastMapper;

    /**
     * 封装queue
     * @param id 任务ID
     * @param duration 时长（天）
     * @param body 标题
     * @return
     */
    public BroadcastThread(Long id,Integer duration,String body){
        this.delayQueue = new DelayQueue();
        ItemDelayed item = new ItemDelayed();
        item.setId(id);
        item.setBody(body);
        Long exeTime = CommonTypeSwitch.getTimestampOfDateTime(LocalDateTime.now().plusDays(duration));
        item.setTime(exeTime);
        this.delayQueue.offer(item);
    }

    public BroadcastThread(DelayQueue<ItemDelayed> delayQueue){
        this.delayQueue = delayQueue;
    }


    @Override
    public void run() {
        while (true) {
            try {
                ItemDelayed take = delayQueue.take();
                log.info("消费消息id：" + take.getId()+ " 消息体：" + take.getBody());
                //道具服务时间过期，修改广播列表 该任务等广播状态置为失效
                Broadcast entity = broadcastMapper.queryByTaskId(take.getId(),StatusEnum.BroadcastStatus.PROCESSING.getCode(),
                        StatusEnum.DflagStatus.VALID.getCode());
                if (null != entity){
                    Broadcast record = new Broadcast();
                    record.setStatus(StatusEnum.BroadcastStatus.OVER.getCode());
                    record.setId(entity.getId());
                    record.setUpdateTime(new Date());
                    record.setUpdateBy(ConstantValue.L_ZERO);
                    broadcastMapper.updateByPrimaryKeySelective(record);
                }
            } catch (InterruptedException e) {
                log.error("error:",e);
            }
        }
    }
}

如果发生断电情况，导致数据丢失，可以加上数据库，把需要发到延时队列到数据都存到数据库+版本（防止重复消费），每次重启项目扫描数据填充到队列里，删除数据库失败的不进行业务处理，或者先业务处理，删除失败回滚业务（业务也要有版本，防止重复操作）