生产消费者模型

生产者消费者模型具体来讲，就是在一个系统中，存在生产者和消费者两种角色，他们通过内存缓冲区进行通信，生产者生产消费者需要的资料，消费者把资料做成产品。生产消费者模式如下图。

采用synchronized锁以及wait notify方法实现

代码源自菜鸟教程

//生产者消费者模型
public class ProducerConsumerTest {
    public static void main(String[] args) {
        CubbyHole c = new CubbyHole();
        Producer p1 = new Producer(c, 1);
        Consumer c1 = new Consumer(c, 1);
        p1.start();
        c1.start();
    }
}
class CubbyHole {
    private int contents;
    private boolean available = false;
    public synchronized int get() {
        while (available == false) {
            try {
                wait();
            }
            catch (InterruptedException e) {
            }
        }
        available = false;
        notifyAll();
        return contents;
    }
    public synchronized void put(int value) {
        while (available == true) {
            try {
                wait();
            }
            catch (InterruptedException e) {
            }
        }
        contents = value;
        available = true;
        notifyAll();
    }
}

class Consumer extends Thread {
    private CubbyHole cubbyhole;
    private int number;
    public Consumer(CubbyHole c, int number) {
        cubbyhole = c;
        this.number = number;
    }
    public void run() {
        int value = 0;
        for (int i = 0; i < 10; i++) {
            value = cubbyhole.get();
            System.out.println("消费者 #" + this.number+ " got: " + value);
        }
    }
}

class Producer extends Thread {
    private CubbyHole cubbyhole;
    private int number;

    public Producer(CubbyHole c, int number) {
        cubbyhole = c;
        this.number = number;
    }

    public void run() {
        for (int i = 0; i < 10; i++) {
            cubbyhole.put(i);
            System.out.println("生产者 #" + this.number + " put: " + i);
            try {
                sleep((int)(Math.random() * 100));
            } catch (InterruptedException e) { }
        }
    }
}

运行结果：

消费者 #1 got: 0
生产者 #1 put: 0
生产者 #1 put: 1
消费者 #1 got: 1
生产者 #1 put: 2
消费者 #1 got: 2
生产者 #1 put: 3
消费者 #1 got: 3
生产者 #1 put: 4
消费者 #1 got: 4
消费者 #1 got: 5
生产者 #1 put: 5
生产者 #1 put: 6
消费者 #1 got: 6
消费者 #1 got: 7
生产者 #1 put: 7
消费者 #1 got: 8
生产者 #1 put: 8
生产者 #1 put: 9
消费者 #1 got: 9

采用阻塞队列实现

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

class MyResource{
    private volatile boolean FLAG = true;//默认开启，进行生产+消费。volatile为了让所有线程都可见
    private AtomicInteger atomicInteger = new AtomicInteger();

    BlockingQueue<String> blockingQueue = null;
    public MyResource(BlockingQueue<String> blockingQueue) //传接口，可扩展性强
    {
        this.blockingQueue = blockingQueue;
        System.out.println(blockingQueue.getClass().getName());//我要知道传过来的是什么
    }

    public void myProd() throws Exception{
        String data = null;
        boolean retValue;
        while(FLAG){
            data = atomicInteger.incrementAndGet()+"";
            retValue = blockingQueue.offer(data,2L, TimeUnit.SECONDS);//2秒取一次
            if(retValue){
                System.out.println(Thread.currentThread().getName()+"\t插入队列"+data+"成功");
            }else{
                System.out.println(Thread.currentThread().getName()+"\t插入队列"+data+"失败");
            }
            TimeUnit.SECONDS.sleep(1);
        }
        System.out.println(Thread.currentThread().getName()+"\t生产停止");
    }

    public void myConsumer() throws Exception{
        String result = null;
        while(FLAG){
            result = blockingQueue.poll(2L,TimeUnit.SECONDS);//2秒取不到返回null
            if(null==result || result.equalsIgnoreCase("")){
                FLAG = false;
                System.out.println(Thread.currentThread().getName()+"\t 超过2秒，消费退出");
                System.out.println();
                System.out.println();
                return;
            }
            System.out.println(Thread.currentThread().getName()+"\t消费队列"+result+"成功");
        }
    }

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

/*
 * volatile/CAS/atomicInteger/BlockQueue/线程交互/原子引用
 * */

public class ProdConsumer_BlockQueueDemo {
    public static void main(String[] args) throws Exception{
        MyResource myResource = new MyResource(new ArrayBlockingQueue<>(10));

        new Thread(()->{
            System.out.println(Thread.currentThread().getName()+"\t 生产线程启动");
            System.out.println();
            System.out.println();
            try{
                myResource.myProd();
            }catch (Exception e){
                e.printStackTrace();
            }
        },"Prod").start();

        new Thread(()->{
            System.out.println(Thread.currentThread().getName()+"\t 消费线程启动");
            try{
                myResource.myConsumer();
            }catch (Exception e){
                e.printStackTrace();
            }
        },"Consumer").start();

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

        System.out.println();
        System.out.println();
        System.out.println();

        System.out.println("5秒钟到，main停止");
        myResource.stop();
    }
}

运行结果：

java.util.concurrent.ArrayBlockingQueue
Prod	 生产线程启动


Prod	插入队列1成功
Consumer	 消费线程启动
Consumer	消费队列1成功
Prod	插入队列2成功
Consumer	消费队列2成功
Prod	插入队列3成功
Consumer	消费队列3成功
Prod	插入队列4成功
Consumer	消费队列4成功
Prod	插入队列5成功
Consumer	消费队列5成功



5秒钟到，main停止
Prod	生产停止
Consumer	 超过2秒，消费退出