摘自《Java編程思想》

package com.test.concurrency;import java.util.ArrayList; import java.util.List; import java.util.Queue; import java.util.Random; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.PriorityBlockingQueue; import java.util.concurrent.TimeUnit;class PrioritizedTask implements Runnable, Comparable<PrioritizedTask> {private Random rand = new Random(47);private static int counter = 0;private final int id = counter++;private final int priority;// 用于表示當前任務的執行優先級protected static List<PrioritizedTask> sequence = new ArrayList<PrioritizedTask>();public PrioritizedTask(int priority){this.priority = priority;sequence.add(this);}/*** 用于比較任務的優先級*/@Overridepublic int compareTo(PrioritizedTask o){return priority < o.priority ? 1 : (priority > o.priority ? -1 : 0);}@Overridepublic void run(){try{TimeUnit.MILLISECONDS.sleep(rand.nextInt(250));}catch (InterruptedException e){e.printStackTrace();}System.out.println(this);}@Overridepublic String toString(){return String.format("[%1$-3d]", priority) + " Task " + id;}public String summary(){return "(" + id + ":" + priority + ")";}}/*** 該任務負責展示當前sequence中的任務與正常執行的任務進行對比以及停止線程*/ class EndSentinel extends PrioritizedTask {private ExecutorService exec;public EndSentinel(ExecutorService e){super(-1);exec = e;}public void run(){int count = 0;for (PrioritizedTask pt : sequence){System.out.println(pt.summary());if (++count % 5 == 0){System.out.println();}}System.out.println();System.out.println(this + " Calling shutdownNow");exec.shutdownNow();} }/***負責生成任務，分別造不同級別的任務添加到執行隊列中 **/ class PrioritizedTaskProduncer implements Runnable {private Random rand = new Random(47);private Queue<Runnable> queue;private ExecutorService exec;public PrioritizedTaskProduncer(Queue<Runnable> q, ExecutorService e){queue = q;exec = e;}@Overridepublic void run(){//20個不同優先級的任務，通過隨機數來產生for (int i = 0; i < 20; i++){queue.add(new PrioritizedTask(rand.nextInt(10)));Thread.yield();}try{//20個優先級高的任務for (int i = 0; i < 10; i++){TimeUnit.MILLISECONDS.sleep(250);queue.add(new PrioritizedTask(10));}//優先級0-9的執行任務for (int i = 0; i < 10; i++){queue.add(new PrioritizedTask(i));}queue.add(new EndSentinel(exec));}catch (InterruptedException e){e.printStackTrace();}System.out.println("Finished PrioritizedTaskProducer");} } /***負責消費任務*/ class PrioritizedTaskConsumer implements Runnable {private PriorityBlockingQueue<Runnable> q;public PrioritizedTaskConsumer(PriorityBlockingQueue<Runnable> q){this.q = q;}@Overridepublic void run(){try{while (!Thread.interrupted()){q.take().run();}}catch (InterruptedException e){e.printStackTrace();}System.out.println("Finished PrioritizedTaskConsumer");} }public class PriorityBlockingQueueDemo {public static void main(String[] args) throws InterruptedException{ExecutorService exec = Executors.newCachedThreadPool();PriorityBlockingQueue<Runnable> queue = new PriorityBlockingQueue<Runnable>();exec.execute(new PrioritizedTaskProduncer(queue, exec));//此處需特別注意，需要等待所有的任務已經生成完后，再執行消費，否則，可能會看到消費并非按照優先級執行的Thread.sleep(5000);exec.execute(new PrioritizedTaskConsumer(queue));} }

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轉載于:https://www.cnblogs.com/woniu4/p/9140899.html

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