BlockingQueue阻塞队列

BlockingQueue阻塞队列

BlockingQueue的四组API

/**BlockQueue的四组API
 * 1.抛出异常
 * 2.有返回值，不抛出异常
 * 3.阻塞等待
 * 4.超时等待
 */
public class BlockQueueTest {
    public static void main(String[] args) throws InterruptedException {
        test03();
    }

    /**抛出异常
     * */
    public static void test01(){
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);//队列的长度
        System.out.println(blockingQueue.add("a"));
        System.out.println(blockingQueue.add("b"));
        System.out.println(blockingQueue.add("c"));
        //获取队首元素
        System.out.println(blockingQueue.element());
        //IllegalStateException: Queue full 抛出异常，列满
                  //blockingQueue.add("d");
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        //.NoSuchElementException 队空
        //System.out.println(blockingQueue.remove());

    }
    /**不抛出异常，有返回值
     * */
    public static void test02(){
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.offer("a"));
        System.out.println(blockingQueue.offer("b"));
        System.out.println(blockingQueue.offer("c"));
        //获取队首元素
        System.out.println(blockingQueue.peek());
        //有返回值，不抛出异常
       // System.out.println(blockingQueue.offer("d"));
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        //有返回值，不抛出异常
        //System.out.println(blockingQueue.poll());
    }
    /**阻塞等待，一直阻塞
     * */
    public static void test03() throws InterruptedException {
        ArrayBlockingQueue arrayBlockingQueue = new ArrayBlockingQueue<>(3);
        arrayBlockingQueue.put("a");
        arrayBlockingQueue.put("b");
        arrayBlockingQueue.put("c");
        //队满，阻塞等待，一直等待
        //arrayBlockingQueue.put("d");
        System.out.println(arrayBlockingQueue.take());
        System.out.println(arrayBlockingQueue.take());
        System.out.println(arrayBlockingQueue.take());
        //队空，阻塞等待，一直等待
        //System.out.println(arrayBlockingQueue.take());
    }
    /**
     *超时等待，但不会一直等待，阻塞时间内等待，之后退出
     */
    public static void test04() throws InterruptedException {
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.offer("a", 2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("b", 2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("c", 2, TimeUnit.SECONDS));
        //阻塞两秒，队满返回false退出
        // System.out.println(blockingQueue.offer("c", 2, TimeUnit.SECONDS));

        System.out.println(blockingQueue.poll(2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.poll(2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.poll(2, TimeUnit.SECONDS));
        //阻塞异常，阻塞两秒，队空返回null
        // System.out.println(blockingQueue.poll(2, TimeUnit.SECONDS));
    }
}

SynchronousQueue同步队列

特点：

• 插入操作必须等待队列中的上一个元素被取出后才能插入，反之亦然。

• 同步队列没有存储空间

• 存储元素操作put（） ，读取操作take( )

//同步队列
public class SynchronousQueueTest {
    public static void main(String[] args) {
        //SynchronousQueue是BlockingQueue的子类
        BlockingQueue<String> synchronousQueue = new SynchronousQueue<>();
        new Thread(()->{
            try {
                System.out.println(Thread.currentThread().getName()+" put1");
                synchronousQueue.put("a");
                System.out.println(Thread.currentThread().getName()+" put2");
                synchronousQueue.put("b");
                System.out.println(Thread.currentThread().getName()+" put3");
                synchronousQueue.put("c");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();
        new Thread(()->{
            try {
                TimeUnit.SECONDS.sleep(3);
                System.out.println(Thread.currentThread().getName()+"----"+synchronousQueue.take());
                TimeUnit.SECONDS.sleep(3);
                System.out.println(Thread.currentThread().getName()+"----"+synchronousQueue.take());
                TimeUnit.SECONDS.sleep(3);
                System.out.println(Thread.currentThread().getName()+"----"+synchronousQueue.take());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"B").start();
    }
}