Java DelayQueue包装类

public class DelayQueueWrapper<T> {

    private TimeUnit timeUnit;

    private final Long capacity;

    private long currentSize;

    private DelayQueue<DelayQueueTarget<T>> delayQueue;

    public DelayQueueWrapper(long capacity, TimeUnit timeUnit) {

        this.delayQueue = new DelayQueue<>();

        this.capacity = capacity;

        this.currentSize = 0;

    }

    /**

     * offer element

     * @param t

     * @param delay

     * @return

     */

    public synchronized boolean offer(T t, long delay) {

        if (this.currentSize > capacity) {

            return false;

        }

        this.delayQueue.add(new DelayQueueTarget<T>(t, timeUnit.toMillis(delay)));

        this.currentSize++;

        return true;

    }

    /**

     * peek element

     * @return

     */

    public synchronized T peek(){

        if (this.currentSize < 0) {

            return null;

        }

        T t = Optional.ofNullable(this.delayQueue.peek())

                .map(DelayQueueTarget::getData)

                .orElse(null);

        this.currentSize--;

        return t;

    }

    public static class DelayQueueTarget<T> implements Delayed{

        private T data;

        private long startTime;

        public DelayQueueTarget(T data, long delayInMilliseconds) {

            this.data = data;

            this.startTime = System.currentTimeMillis() + delayInMilliseconds;

        }

        @Override

        public long getDelay(TimeUnit unit) {

            long diff = startTime - System.currentTimeMillis();

            return unit.convert(diff, TimeUnit.MILLISECONDS);

        }

        @Override

        public int compareTo(Delayed o) {

            return Ints.saturatedCast(

                    this.startTime - ((DelayQueueTarget<?>) o).startTime);

        }

        public T getData() {

            return data;

        }

    }

}
巴特西

Java DelayQueue包装类

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