java PriorityBlockingQueue 基于优先级队列。的读出操作可以阻止.
package org.rui.thread.newc; 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; /*** * 这是一个基于优选级队列。它具有可堵塞的读取操作。* 以下是一个演示样例，当中在优级级队列的对象是依照优级级顺序从队列中出现的任务。
* prioritizedTask被赋予了一个优先级数字， 以此来提供这样的顺序。 * @author lenovo * */ 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; protected static List<PrioritizedTask> sequence = new ArrayList<PrioritizedTask>(); public PrioritizedTask(int priority) { this.priority = priority; sequence.add(this); } @Override public int compareTo(PrioritizedTask o) { return priority < o.priority ?
1 : (priority > o.priority ?
-1 : 0); } @Override public void run() { try { TimeUnit.MILLISECONDS.sleep(rand.nextInt(250)); } catch (InterruptedException e) { // Acceptable way to exit 可接受的方式退出 } System.out.println("PrioritizedTask run: " + this); } @Override public String toString() { return String.format("[%1$-3d]", priority) + " =Task >>id: " + id; } public String summary() { return "(id:" + id + " priority:" + priority + ")"; } // // public static class endSentinel extends PrioritizedTask { private ExecutorService exec; public endSentinel(ExecutorService e) { super(-1);// lowest priority in this program 最低优先级 exec = e; } @Override public void run() { int count = 0; for (PrioritizedTask pt : sequence) { System.out.println("summary汇总: "+pt.summary()); if (++count % 5 == 0) { System.out.println(); } } System.out.println(); System.out.println(this + " calling shutdownNow"); exec.shutdownNow(); } } } // //////////////生产者//////// class prioritizedTaskProducer implements Runnable { private Random rand = new Random(47); private Queue<Runnable> queue; private ExecutorService exec; public prioritizedTaskProducer(Queue<Runnable> q, ExecutorService e) { queue = q; exec = e;// used for end sentinel 用于结束哨兵 } @Override public void run() { // unbounded queue ; never blocks 无界队列;从不堵塞 // fill it up fast with random priorities 把它填平高速随机的优先级 for (int i = 0; i < 20; i++) { int temp=0; System.out.println("入队列>>随机20>>10>inner:"+(temp=rand.nextInt(10))); queue.add(new PrioritizedTask(temp)); Thread.yield();// 让当前线程回到可运行状态，以便让具有同样优先级的线程进入运行状态，但不是绝对的。
由于虚拟机可能会让该线程又一次进入运行状态。 } // trickle in highest-priority jobs 细流在最高优先级的工作 try { //放入10 个10 for (int i = 0; i < 10; i++) { System.out.println("入队列>>指定10>>10个:"+10); TimeUnit.MILLISECONDS.sleep(2500); queue.add(new PrioritizedTask(10)); } for (int i = 0; i < 10; i++) { System.out.println("入队列>>自增>>10>0-10:"+i); // add jobs lowest priority first: 加入工作 最低优先级: queue.add(new PrioritizedTask(i)); } // a sentinel to stop all the tasks 哨兵停止全部的任务 queue.add(new PrioritizedTask.endSentinel(exec)); } catch (InterruptedException e) { // 可接受的方式退出 System.out.println("InterruptedException >>143"); } System.out.println("完毕 prioritizedTaskProducer"); } } // //消费者////PriorityBlockingQueue///////// class prioritizedTaskConsumer implements Runnable { private PriorityBlockingQueue<Runnable> q; public prioritizedTaskConsumer(PriorityBlockingQueue<Runnable> q) { this.q = q; } @Override public void run() { try { while (!Thread.interrupted()) { // use current thread to run the task 使用当前线程运行的任务 q.take().run(); } } catch (InterruptedException e) { // acceptable way to exit } System.out.println("完毕 prioritizedTaskConsumer"); } } /*** * main * @author lenovo * */ public class PriorityBlockingQueueDemo { public static void main(String[] args) throws InterruptedException { Random randx = new Random(47); int c = randx.nextInt(250); System.out.println(c); ExecutorService exec = Executors.newCachedThreadPool(); PriorityBlockingQueue<Runnable> queue = new PriorityBlockingQueue<Runnable>(); exec.execute(new prioritizedTaskProducer(queue, exec));// 生产者 // Thread.sleep(8000); exec.execute(new prioritizedTaskConsumer(queue));// 消费者 } } /** output: sle--- 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:5 入队列>>随机20>>10>inner:3 入队列>>随机20>>10>inner:1 入队列>>随机20>>10>inner:1 入队列>>随机20>>10>inner:9 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:0 入队列>>随机20>>10>inner:2 入队列>>随机20>>10>inner:7 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:1 入队列>>随机20>>10>inner:9 入队列>>随机20>>10>inner:9 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:8 入队列>>随机20>>10>inner:1 入队列>>随机20>>10>inner:0 入队列>>随机20>>10>inner:8 入队列>>指定10>>10个:10 入队列>>指定10>>10个:10 入队列>>指定10>>10个:10 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 20 PrioritizedTask run: [10 ] =Task >>id: 21 PrioritizedTask run: [10 ] =Task >>id: 22 PrioritizedTask run: [9 ] =Task >>id: 5 PrioritizedTask run: [9 ] =Task >>id: 13 PrioritizedTask run: [9 ] =Task >>id: 14 PrioritizedTask run: [8 ] =Task >>id: 15 PrioritizedTask run: [8 ] =Task >>id: 16 PrioritizedTask run: [8 ] =Task >>id: 19 PrioritizedTask run: [8 ] =Task >>id: 0 PrioritizedTask run: [8 ] =Task >>id: 10 PrioritizedTask run: [8 ] =Task >>id: 11 PrioritizedTask run: [8 ] =Task >>id: 6 PrioritizedTask run: [7 ] =Task >>id: 9 PrioritizedTask run: [5 ] =Task >>id: 1 PrioritizedTask run: [3 ] =Task >>id: 2 PrioritizedTask run: [2 ] =Task >>id: 8 PrioritizedTask run: [1 ] =Task >>id: 12 PrioritizedTask run: [1 ] =Task >>id: 17 PrioritizedTask run: [1 ] =Task >>id: 4 PrioritizedTask run: [1 ] =Task >>id: 3 PrioritizedTask run: [0 ] =Task >>id: 7 PrioritizedTask run: [0 ] =Task >>id: 18 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 23 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 24 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 25 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 26 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 27 入队列>>指定10>>10个:10 PrioritizedTask run: [10 ] =Task >>id: 28 入队列>>自增>>10>0-10:0 入队列>>自增>>10>0-10:1 入队列>>自增>>10>0-10:2 入队列>>自增>>10>0-10:3 入队列>>自增>>10>0-10:4 入队列>>自增>>10>0-10:5 入队列>>自增>>10>0-10:6 入队列>>自增>>10>0-10:7 入队列>>自增>>10>0-10:8 入队列>>自增>>10>0-10:9 完毕 prioritizedTaskProducer PrioritizedTask run: [10 ] =Task >>id: 29 PrioritizedTask run: [9 ] =Task >>id: 39 PrioritizedTask run: [8 ] =Task >>id: 38 PrioritizedTask run: [7 ] =Task >>id: 37 PrioritizedTask run: [6 ] =Task >>id: 36 PrioritizedTask run: [5 ] =Task >>id: 35 PrioritizedTask run: [4 ] =Task >>id: 34 PrioritizedTask run: [3 ] =Task >>id: 33 PrioritizedTask run: [2 ] =Task >>id: 32 PrioritizedTask run: [1 ] =Task >>id: 31 PrioritizedTask run: [0 ] =Task >>id: 30 summary汇总: (id:0 priority:8) summary汇总: (id:1 priority:5) summary汇总: (id:2 priority:3) summary汇总: (id:3 priority:1) summary汇总: (id:4 priority:1) summary汇总: (id:5 priority:9) summary汇总: (id:6 priority:8) summary汇总: (id:7 priority:0) summary汇总: (id:8 priority:2) summary汇总: (id:9 priority:7) summary汇总: (id:10 priority:8) summary汇总: (id:11 priority:8) summary汇总: (id:12 priority:1) summary汇总: (id:13 priority:9) summary汇总: (id:14 priority:9) summary汇总: (id:15 priority:8) summary汇总: (id:16 priority:8) summary汇总: (id:17 priority:1) summary汇总: (id:18 priority:0) summary汇总: (id:19 priority:8) summary汇总: (id:20 priority:10) summary汇总: (id:21 priority:10) summary汇总: (id:22 priority:10) summary汇总: (id:23 priority:10) summary汇总: (id:24 priority:10) summary汇总: (id:25 priority:10) summary汇总: (id:26 priority:10) summary汇总: (id:27 priority:10) summary汇总: (id:28 priority:10) summary汇总: (id:29 priority:10) summary汇总: (id:30 priority:0) summary汇总: (id:31 priority:1) summary汇总: (id:32 priority:2) summary汇总: (id:33 priority:3) summary汇总: (id:34 priority:4) summary汇总: (id:35 priority:5) summary汇总: (id:36 priority:6) summary汇总: (id:37 priority:7) summary汇总: (id:38 priority:8) summary汇总: (id:39 priority:9) summary汇总: (id:40 priority:-1) [-1 ] =Task >>id: 40 calling shutdownNow 完毕 prioritizedTaskConsumer */ /** *与前一个演示样例同样，prioritizedTask对象的创建序列被记录在sequence list中，用于和实际的运行顺序比較。 *run()方法将休眠一小段随机的时间 ，然后打印对象信息，而EndSentinel提供了和前面同样的功能， *要确保它是队列中最后一个对象。 * *PrioritizedTaskProducer和PrioritizedTaskComsumer通过PriorityBlockingQueue彼此连接。 *由于这样的队列的堵塞特性提供了全部必需的同步。所以你应该注意到了，这里不须要不论什么显式的同步--不必考虑你从这样的队列中读取时 *，基中是否有无素，由于这个队列在没有元素时，将直接堵塞读取靠。
* * */
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