DelayQueue的使用

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

/**
 * @author James.Ge
 * @description
 * @date 2025-09-28
 */
public class DelayQueueDemo {
    static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    public static void main(String[] args) throws InterruptedException {
        DelayQueue<DelayedTask> queue = new DelayQueue<>();

        // 添加3个延迟任务
        queue.put(new DelayedTask("Task-1", 5, TimeUnit.SECONDS));
        queue.put(new DelayedTask("Task-2", 10, TimeUnit.SECONDS));
        queue.put(new DelayedTask("Task-3", 15, TimeUnit.SECONDS));

        System.out.println("开始时间: " + LocalDateTime.now().format(formatter));

        while (!queue.isEmpty()) {
            DelayedTask task = queue.take();
            System.out.println("执行: " + task + " 当前时间: " + LocalDateTime.now().format(formatter));
        }
    }
}


class DelayedTask implements Delayed {
    private final String taskName;
    private final LocalDateTime executeTime;

    public DelayedTask(String taskName, long delay, TimeUnit unit) {
        this.taskName = taskName;
        this.executeTime = LocalDateTime.now().plus(delay, unit.toChronoUnit());
//        this.executeTime = System.currentTimeMillis() + unit.toMillis(delay);
    }

    @Override
    public long getDelay(TimeUnit unit) {
//        return unit.convert(executeTime - System.currentTimeMillis(), TimeUnit.MILLISECONDS);

        LocalDateTime minus = executeTime.minus(System.currentTimeMillis(), TimeUnit.MILLISECONDS.toChronoUnit());
        long timestamp = minus
                .toInstant(ZoneOffset.of("+8"))
                .toEpochMilli();

        return unit.convert(timestamp, TimeUnit.MILLISECONDS);
    }


    @Override
    public int compareTo(Delayed o) {
        long epochMilli0 = this.executeTime.toInstant(ZoneOffset.of("+8"))
                .toEpochMilli();
        long epochMilli1 = ((DelayedTask) o).executeTime.toInstant(ZoneOffset.of("+8"))
                .toEpochMilli();
        return Long.compare(epochMilli0, epochMilli1);
    }

    @Override
    public String toString() {
        return "Task: " + taskName + " (Execute at: " + executeTime.format(DelayQueueDemo.formatter) + ")";
    }
}