基于BlockingQueue的生产者-消费者模型

不管是在学习操作系统知识还是Java多线程知识的时候，都会遇到生产者-消费者模型。我们必须熟练地写出一个简单的模型。之前的使用的大多数都是synchronized锁同步代码块或修饰方法或是使用ReetrantLock来完成，这里介绍使用java.util.concurrent包提供的BlockingQueue来实现。

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

class CakeShop{
    //使用volatile修饰，保证多个线程之间的可见性
    private volatile boolean FLAG = true;
    private AtomicInteger cake = new AtomicInteger(0);
    private BlockingQueue<String> blockingQueue;

    //传参传接口，方便多种不同的需求
    CakeShop(BlockingQueue<String> blockingQueue) {
        this.blockingQueue = blockingQueue;
    }

  public void production(){
        String data;
        boolean retValue = false;

        //多线程情况下，使用while进行条件判断
        while (FLAG) {
            data = cake.incrementAndGet() + "";
            try {
                retValue = blockingQueue.offer(data, 2L, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            if (retValue) {
                System.out.println(Thread.currentThread().getName() + "\t生产队列，生产蛋糕" + data + "，成功");
            } else {
                System.out.println(Thread.currentThread().getName() + "\t生产队列，生产蛋糕" + data + "，失败");
            }

            //模拟生产过程
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        }

        System.out.println((Thread.currentThread().getName() + "\tflag=false,停止生产！"));

    }

    public void consumption(){
        String res = "";
        while (FLAG) {

            try {
                res = blockingQueue.poll(2L, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            if (res == null || res.equalsIgnoreCase("")) {
                FLAG = false;
                System.out.println(Thread.currentThread().getName() + "\t 超过两秒钟未取到蛋糕，停止消费");
                System.out.println();
                System.out.println();
                return;
            }

            System.out.println(Thread.currentThread().getName() + "\t 消费队列，消费蛋糕" + res + "，成功！");
        }
    }

    public void stop(){
        this.FLAG = false;
    }
}



public class ProdConsumerWithBlockingQueue {

    public static void main(String[] args) {
        CakeShop cakeShop = new CakeShop(new ArrayBlockingQueue<>(10));

        new Thread(() -> {
            System.out.println(Thread.currentThread().getName() + "\t启动");
            cakeShop.production();
        }, "生产者线程").start();

        new Thread(() -> {
            System.out.println(Thread.currentThread().getName() + "\t启动");

            try {
                cakeShop.consumption();
                System.out.println();
                System.out.println();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }, "消费者线程").start();


        try {
            TimeUnit.SECONDS.sleep(5);
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.out.println("============================");

        System.out.println("五秒钟时间到，停止活动！");

        cakeShop.stop();
    }
}