易百教程

290、阻塞队列是什么?

java.util.concurrent.BlockingQueue 是 Queue 的子接口,支持诸如在插入新值之前等待空间可用性或在从中检索元素之前等待队列变为非空等操作。参考以下示例。

import java.util.Random;  
import java.util.concurrent.ArrayBlockingQueue;  
import java.util.concurrent.BlockingQueue;  

public class TestThread {  

   public static void main(final String[] arguments) throws InterruptedException {  
      BlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(10);  

      Insert i = new Insert(queue);  
      Retrieve r = new Retrieve(queue);  

      new Thread(i).start();  
      new Thread(r).start();  

      Thread.sleep(2000);  
   }    


   static class Insert implements Runnable {  
      private BlockingQueue<Integer> queue;  

      public Insert(BlockingQueue queue) {  
         this.queue = queue;  
      }  

      @Override  
      public void run() {  
         Random random = new Random();  

         try {  
            int result = random.nextInt(200);  
            Thread.sleep(1000);  
            queue.put(result);  
            System.out.println("Added: " + result);  

            result = random.nextInt(10);  
            Thread.sleep(1000);  
            queue.put(result);  
            System.out.println("Added: " + result);  

            result = random.nextInt(50);  
            Thread.sleep(1000);  
            queue.put(result);  
            System.out.println("Added: " + result);  
         } catch (InterruptedException e) {  
            e.printStackTrace();  
         }  
      }      
   }  

   static class Retrieve implements Runnable {  
      private BlockingQueue<Integer> queue;  

      public Retrieve(BlockingQueue queue) {  
         this.queue = queue;  
      }  

      @Override  
      public void run() {  

         try {  
            System.out.println("Removed: " + queue.take());  
            System.out.println("Removed: " + queue.take());  
            System.out.println("Removed: " + queue.take());  
         } catch (InterruptedException e) {  
            e.printStackTrace();  
         }  
      }  
   }  
}

运行结果如下:

Added: 96
Removed: 96
Added: 8
Removed: 8
Added: 5
Removed: 5