package concurrent2;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
     
        {      private Random rand = new Random(47);      private static int counter = 0;      private final int id = counter++;      private final int priority;            protected static List
      
        sequence = new ArrayList
       
        ();            public PrioritizedTask(int priority)       {          this.priority = priority;          sequence.add(this);      }            @Override      public int compareTo(PrioritizedTask o) {          //复写此方法进行任务执行优先级排序  //      return priority < o.priority ? 1 :  //          (priority > o.priority ? -1 : 0);          if(priority < o.priority)          {              return -1;          }else          {              if(priority > o.priority)              {                  return 1;              }else              {                  return 0;              }          }      }        @Override      public void run() {          //执行任务代码..          try {              TimeUnit.MILLISECONDS.sleep(rand.nextInt(250));          } catch (InterruptedException e) {                        }          System.out.println(this);      }            @Override      public String toString() {          return String.format("[%1$-3d]", priority) + " Task id : " + id;      }            public String summary()      {          return "( Task id : " + id + " _priority : " + priority + ")";      }            /**      * 结束所有任务      */      public static class EndSentinel extends PrioritizedTask      {          private ExecutorService exec;          public EndSentinel(ExecutorService e) {              super(Integer.MAX_VALUE);              exec = e;          }                    public void run()          {              int count = 0;              for(PrioritizedTask pt : sequence)              {                  System.out.print(pt.summary());                  if(++count % 5 == 0)                  {                      System.out.println();                  }              }              System.out.println();              System.out.println(this + "Calling shutdownNow()");              exec.shutdownNow();          }      }  }    /**  * 制造一系列任务,分配任务优先级  */  class PrioritizedTaskProducer implements Runnable  {      private Random rand = new Random(47);      private Queue
        
          queue;      private ExecutorService exec;            public PrioritizedTaskProducer(Queue
         
           q, ExecutorService e)       {          queue = q;          exec = e;      }            @Override      public void run() {                    for(int i = 0; i < 20; i++)          {              queue.add(new PrioritizedTask(rand.nextInt(10)));              Thread.yield();          }                    try {              for (int i = 0; i < 10; i++) {                  TimeUnit.MILLISECONDS.sleep(250);                  queue.add(new PrioritizedTask(10));              }                            for(int i = 0; i < 10; i++)              {                  queue.add(new PrioritizedTask(i));              }                            queue.add(new PrioritizedTask.EndSentinel(exec));                        } catch (InterruptedException e) {                        }                    System.out.println("Finished PrioritizedTaskProducer");      }  }      /**  * 使用PriorityBlockingQueue进行任务按优先级同步执行  */  class PrioritizedTaskConsumer implements Runnable  {      private PriorityBlockingQueue
          
            q; public PrioritizedTaskConsumer(PriorityBlockingQueue
           
             q) { this.q = q; } @Override public void run() { try { while (!Thread.interrupted()) { q.take().run(); } } catch (InterruptedException e) { } System.out.println("Finished PrioritizedTaskConsumer"); } } public class PriorityBlockingQueueDemo { public static void main(String args[]) { ExecutorService exec = Executors.newCachedThreadPool(); PriorityBlockingQueue
            
              queue = new PriorityBlockingQueue
             
              (); exec.execute(new PrioritizedTaskProducer(queue, exec)); try { TimeUnit.MILLISECONDS.sleep(250); } catch (InterruptedException e) { } exec.execute(new PrioritizedTaskConsumer(queue)); } }