java阻塞队列BlockingQueue

1.什么是阻塞队列？

2.为什么用，有什么好处？

3.BlockingQueue的核心方法

3.1抛出异常组

package com.queue;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
    public static void main(String[] args) {

      //  List list= new ArrayList<>();
        BlockingQueue 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.add("d"));

       

        
        System.out.println(blockingQueue.element());


        
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());


    }
}

3.2 特殊值

package com.queue;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
    public static void main(String[] args) {

      //  List list= new ArrayList<>();
        BlockingQueue 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.offer("z"));

        

        System.out.println(blockingQueue.peek());

        

        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());


    }
}

3.3 阻塞

package com.queue;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;


public class BlockingQueueDemo {
    public static void main(String[] args) throws Exception{

      //  List list= new ArrayList<>();
        BlockingQueue blockingQueue =new ArrayBlockingQueue(3);
        blockingQueue.put("a");
        blockingQueue.put("b");
        blockingQueue.put("c");
        System.out.println("======================================");

        
        blockingQueue.put("d");

        blockingQueue.take();
        blockingQueue.take();
        blockingQueue.take();

        
        blockingQueue.take();



    }
}

3.4 超时

package com.queue;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;


public class BlockingQueueDemo {
    public static void main(String[] args) throws Exception{

      //  List list= new ArrayList<>();
        BlockingQueue blockingQueue =new ArrayBlockingQueue(3);
        System.out.println(blockingQueue.offer("a", 2L, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("b", 2L, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("c", 2L, TimeUnit.SECONDS));

        
        System.out.println(blockingQueue.offer("d", 2L, TimeUnit.SECONDS));
    }
}

4. SynchronousQueue

不存储元素的阻塞队列，也即单个元素的对列

package com.queue;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;



public class SynchronousQueueDemo {

    public static void main(String[] args) {

        BlockingQueue blockingQueue = new SynchronousQueue<>();

        new Thread(() -> {
            try {

                System.out.println(Thread.currentThread().getName() + "t put 1");
                blockingQueue.put("1");

                System.out.println(Thread.currentThread().getName() + "t put 2");
                blockingQueue.put("2");

                System.out.println(Thread.currentThread().getName() + "t put 3");
                blockingQueue.put("3");


            } catch (Exception e) {
                e.printStackTrace();
            }
        }, "AAA").start();


        new Thread(() -> {
            try {

                TimeUnit.SECONDS.sleep(5);
                System.out.println(Thread.currentThread().getName()+"t "+ blockingQueue.take());

                TimeUnit.SECONDS.sleep(5);
                System.out.println(Thread.currentThread().getName()+"t "+ blockingQueue.take());

                TimeUnit.SECONDS.sleep(5);
                System.out.println(Thread.currentThread().getName()+"t "+ blockingQueue.take());


            } catch (Exception e) {
                e.printStackTrace();
            }
        }, "BBB").start();

    }
}

结果输出：

AAA   put 1
BBB   1
AAA   put 2
BBB   2
AAA   put 3
BBB   3

5.用途，应在在哪里？ 5.1生产者消费者模式

package com.thread;


import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class ShareData {

    private int number = 0;
    private Lock lock = new ReentrantLock();

    private Condition condition = lock.newCondition();

    public void increment() throws Exception {
        lock.lock();
        try {
            //判断 一定要用while 防止虚假唤醒
            while (number != 0) {

                //等待不能生产
                condition.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + "t" + number);
            //通知唤醒
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public void decrement() throws Exception {
        lock.lock();
        try {
            //判断
            while (number == 0) {

                //等待不能生产
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + "t" + number);
            //通知唤醒
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }


}


public class ProdConstumerDemo {

    public static void main(String[] args) {

        ShareData shareData = new ShareData();
        new Thread(() -> {
            for (int i = 1; i <= 5; i++) {
                try {
                    shareData.increment();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "AA").start();

        new Thread(() -> {
            for (int i = 1; i <= 5; i++) {
                try {
                    shareData.decrement();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "BB").start();


        //=======================================



//        new Thread(() -> {
//            for (int i = 1; i <= 5; i++) {
//                try {
//                    shareData.increment();
//                } catch (Exception e) {
//                    e.printStackTrace();
//                }
//            }
//        }, "CC").start();
//
//        new Thread(() -> {
//            for (int i = 1; i <= 5; i++) {
//                try {
//                    shareData.decrement();
//                } catch (Exception e) {
//                    e.printStackTrace();
//                }
//            }
//        }, "DD").start();



    }
}

输出：

AA   1
BB   0
AA   1
BB   0
AA   1
BB   0
AA   1
BB   0
AA   1
BB   0

java阻塞队列BlockingQueue

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