java DelayQueue 延期队列 21.7.3 -------thinking java 4

package org.rui.thread.newc;import java.util.ArrayList;import java.util.List;import java.util.Random;import java.util.concurrent.DelayQueue;import java.util.concurrent.Delayed;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.TimeUnit;/** * 延期队列 优先级队列的一种变体 *  * @author lenovo *  */class DelayedTask implements Runnable, Delayed{private static int counter = 0;private final int id = counter++;// id 从0++private final int delta;// 多少毫秒停止private final long trigger;// 纳秒停止// 保存了任务被创建的顺序protected static List<DelayedTask> sequence = new ArrayList<DelayedTask>();public DelayedTask(int delayInMilliseconds){delta = delayInMilliseconds;trigger = System.nanoTime()+ TimeUnit.NANOSECONDS.convert(delta, TimeUnit.MILLISECONDS);sequence.add(this);}@Overridepublic void run(){System.out.println(this + " run");}public String toString(){// 1个id对应一项任务 会安顺序来执行任务return String.format("[%1$-4d]", delta) + " Task " + id;}public String summary(){return "(" + id + ":" + delta + ")";}// 排序触发@Overridepublic int compareTo(Delayed o){DelayedTask that = (DelayedTask) o;if (trigger < that.trigger)return -1;if (trigger > that.trigger)return 1;return 0;}/** * 告知延迟到期有多长时间 ，或者延迟在多长时间之前已经到期 */@Overridepublic long getDelay(TimeUnit unit){// 对象到期时间 -现在时间 =执行时间return unit.convert(trigger - System.nanoTime(), TimeUnit.NANOSECONDS);}// 关闭所有事物的途径 具体做剥去 是将其放置为队列的最后一个元素。public static class EndSentinel extends DelayedTask{private ExecutorService exec;public EndSentinel(int delayInMilliseconds, ExecutorService c){super(delayInMilliseconds);exec = c;}@Overridepublic void run(){for (DelayedTask pt : sequence){System.out.print(pt.summary() + " ");}System.out.println();System.out.println(this + "  calling shutdownNow");exec.shutdownNow();}}}// 自身是一个任务class DelayedTaskConsumer implements Runnable{private DelayQueue<DelayedTask> q;public DelayedTaskConsumer(DelayQueue<DelayedTask> q){this.q = q;}@Overridepublic void run(){try{while (!Thread.interrupted()){q.take().run();// run task with the current thread 与当前线程运行的任务}} catch (InterruptedException e){System.out.println("可接受的方式退出=");// 可接受的方式退出}System.out.println("finished delayedTaskConsumer");}}public class DelayQueueDemo{public static void main(String[] args){Random rand = new Random(47);ExecutorService exec = Executors.newCachedThreadPool();DelayQueue<DelayedTask> queue = new DelayQueue<DelayedTask>();// fill with tasks that have random delays:充满随机延迟的任务for (int i = 0; i < 20; i++){queue.put(new DelayedTask(rand.nextInt(5000)));}// 设置停止点queue.add(new DelayedTask.EndSentinel(5000, exec));exec.execute(new DelayedTaskConsumer(queue));}}/** output:[128 ] Task 11 run[200 ] Task 7 run[429 ] Task 5 run[520 ] Task 18 run[555 ] Task 1 run[961 ] Task 4 run[998 ] Task 16 run[1207] Task 9 run[1693] Task 2 run[1809] Task 14 run[1861] Task 3 run[2278] Task 15 run[3288] Task 10 run[3551] Task 12 run[4258] Task 0 run[4258] Task 19 run[4522] Task 8 run[4589] Task 13 run[4861] Task 17 run[4868] Task 6 run(0:4258) (1:555) (2:1693) (3:1861) (4:961) (5:429) (6:4868) (7:200) (8:4522) (9:1207) (10:3288) (11:128) (12:3551) (13:4589) (14:1809) (15:2278) (16:998) (17:4861) (18:520) (19:4258) (20:5000) [5000] Task 20  calling shutdownNowfinished delayedTaskConsumer*/