阻塞队列

FIFO

BlockingQueue

• ArrayBlockingQueue
• LinkedBlockingQueue
• SynchronousQueue

什么时候使用阻塞队列

• 多线程并发处理，A调用B，如果B未执行完,A需要等待
• 多线程，线程池

使用队列

四组API

1. 抛出异常
2. 不会抛出异常
3. 阻塞等待
4. 超时等待

方式	抛出异常	不会抛出异常有返回值	阻塞等待	超时等待
添加	add	offer	put	offer
移除	remove	poll	take	poll
判断队列首部	element	peek

//List BlockingQueue Set
public class Test {
    public static void main(String[] args) throws InterruptedException {
        test4();
    }
    /*
    * 抛出异常
    *
    * Exception in thread "main" java.lang.IllegalStateException: Queue full
	    at java.util.AbstractQueue.add(AbstractQueue.java:98)
	    at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312)
	    at com.ji.BlockingQueue.Test.test1(Test.java:20)
	    at com.ji.BlockingQueue.Test.main(Test.java:9)
    * */
    public static void test1(){
        //队列的大小
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.add("a"));
        System.out.println(blockingQueue.add("b"));
        System.out.println(blockingQueue.add("c"));
       System.out.println(blockingQueue.remove());
         /*System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());*/
        System.out.println(blockingQueue.element());
    }
    /*
       * 不抛出异常有返回值 false
       *
       * */
    public static void test2() {
        //队列的大小
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.offer("a"));
        System.out.println(blockingQueue.offer("b"));
        System.out.println(blockingQueue.offer("c"));
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.peek());

    }
    /*
     * 阻塞等待（一直阻塞）
     *
     * */
    public static void test3() throws InterruptedException {
        //队列的大小
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
        blockingQueue.put("a");
        blockingQueue.put("b");
        blockingQueue.put("c");
        //blockingQueue.put("d");  //队列没有位置时会一直等待
        System.out.println(blockingQueue.take());
        System.out.println(blockingQueue.take());
        System.out.println(blockingQueue.take());
        //System.out.println(blockingQueue.take());  // //队列没有元素时会一直等待


    }

    /*
     * 阻塞等待（等待超时）
     *
     * */
    public static void test4() throws InterruptedException {
        //队列的大小
        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));
        //System.out.println(blockingQueue.offer("d", 2, TimeUnit.SECONDS));//等待超过两秒就退出
        System.out.println(blockingQueue.poll(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));


    }
}