BlockingQueue之DelayQueue的学习使用

DelayQueue 是一中阻塞队列,需要实现接口Delayed定义的方法.做下使用记录和心得吧,

@Datapublic class DelayQueueExample implements Delayed {

private String beginTime;    private String name;

public static DateTimeFormatter dateTimeFormatter=DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");    public  LocalDateTime localDateTime;

public DelayQueueExample(String beginTime, String name) {        this.beginTime = beginTime ;        this.name = name;    }

@Override    public long getDelay(TimeUnit unit) {

// TimeUnit.NANOSECONDS.convert(1000,TimeUnit.DAYS);        //long ss= unit.convert(afterTime - System.nanoTime(), TimeUnit.MILLISECONDS);       // System.out.println("getDelay()"+ss);       //unit.convert(afterTime - System.nanoTime(), TimeUnit.MILLISECONDS)

//与当前时间对比,小于当前时间的话就进入队列,否则就抛弃这个队列的数据        localDateTime=  LocalDateTime.parse(beginTime,dateTimeFormatter);        return localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli()- System.currentTimeMillis();//是否小于当前时间

}

@Override    public int compareTo(Delayed o) {        int temp = (int) (o.getDelay(TimeUnit.MILLISECONDS) - this.getDelay(TimeUnit.MILLISECONDS));        if (temp < 0) {            return 1;        }else {            return -1;        }       // return (int) (o.getDelay(TimeUnit.MILLISECONDS) - this.getDelay(TimeUnit.MILLISECONDS));    }

@Override    public String toString() {        return "DelayQueueExample{" +                "beginTime=" +(beginTime) +                ", name=‘" + name + ‘\‘‘ +                ‘}‘;    }

public static void main(String[] args) throws InterruptedException {        DelayQueue<DelayQueueExample> delayQueue = new DelayQueue<DelayQueueExample>();        delayQueue.add(new DelayQueueExample("2018-06-18 00:45:00", "hhe100"));        delayQueue.add(new DelayQueueExample("2018-06-18 00:47:00", "hhe101"));        delayQueue.add(new DelayQueueExample("2018-06-08 00:46:00", "hhe102"));        new Thread(new Runnable() {            @Override            public void run() {                while (true) {                    DelayQueueExample element = null;                    try {                        element = delayQueue.poll();                        if (element == null) {                            break;                        } else {                            System.out.println(element);                        }                    } catch (Exception e) {                        e.printStackTrace();                    }                }            }        }).start();

}}

源码部分:取值的逻辑相似

 public E poll() {
        final ReentrantLock lock = this.lock;
        lock.lock();
        try {
            E first = q.peek();
            if (first == null || first.getDelay(NANOSECONDS) > 0)//丢掉延迟大于0的队列值
                return null;
            else
                return q.poll();
        } finally {
            lock.unlock();
        }
    }

超时加排序机制

原文地址：https://www.cnblogs.com/jinjian91/p/9193325.html