java并发编程生产者消费者模式-蒲公英云

java并发编程生产者消费者模式

水深无声 2022-11-20 00:59 257阅读 0赞

为什么要使用生产者和消费者模式

由于生产与消费是两块功能，所以很难保证两块处理速度完全一致，为了解决这种生产消费能力不均衡的问题，所以便有了生产者和消费者模式。

什么是生产者消费者模式

生产者和消费者彼此之间不直接通讯，而通过阻塞队列来进行通讯

实现方式一使用队列：

使用队列，生产者与消费之间通过队列相连，生产者将生产资料放入队列，消费者从队列里面取资源消费。

生产者消费者的示例代码：
    生产者：
            import java.util.concurrent.BlockingQueue;
    public class Producer implements Runnable {
        BlockingQueue<String> queue;
        public Producer(BlockingQueue<String> queue) {
            this.queue = queue;
        }
        @Override
        public void run() {
            try {
                String temp = "A Product, 生产线程："
                        + Thread.currentThread().getName();
                System.out.println("I have made a product:"
                        + Thread.currentThread().getName());
                queue.put(temp);//如果队列是满的话，会阻塞当前线程
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    消费者：
            import java.util.concurrent.BlockingQueue;
    public class Consumer implements Runnable {
        BlockingQueue<String> queue;
        public Consumer(BlockingQueue<String> queue) {
            this.queue = queue;
        }
        @Override
        public void run() {
            try {
                String temp = queue.take();//如果队列为空，会阻塞当前线程
                System.out.println(temp);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    测试类：
            import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
    public class Test3 {
        public static void main(String[] args) {
        BlockingQueue<String> queue = new LinkedBlockingQueue<String>(2);
// BlockingQueue<String> queue = new LinkedBlockingQueue<String>();
//不设置的话，LinkedBlockingQueue默认大小为Integer.MAX_VALUE
// BlockingQueue<String> queue = new ArrayBlockingQueue<String>(2);
            Consumer consumer = new Consumer(queue);
            Producer producer = new Producer(queue);
            for (int i = 0; i < 5; i++) {
                new Thread(producer, "Producer" + (i + 1)).start();
                new Thread(consumer, "Consumer" + (i + 1)).start();
            }
        }
    }
    打印结果：
    I have
    made a
    product:Producer1
    I have
    made a
    product:Producer2
    A Product, 生产线程：Producer1
    A Product, 生产线程：Producer2
    I have
    made a
    product:Producer3
    A Product, 生产线程：Producer3
    I have
    made a
    product:Producer5
    I have
    made a
    product:Producer4
    A Product, 生产线程：Producer5
    A Product, 生产线程：Producer4

实现方式二阻塞线程：

生产者生产产品阻塞线程，结束后唤醒线程，消费者进行消费。

class Restaurant{
    private Object obj;
    public void put(){
        while (true) {
            synchronized (this) {
                while (obj != null) {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                obj = new Object();
                System.out.print("Order up!  ");
                notifyAll();
            }
        }
    }
    public void get(){
        while (true) {
            synchronized (this) {
                while (obj == null) {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                System.out.println("waiter get meal");
                obj = null;
                notifyAll();
            }
        }
    }
}
class Chef extends Thread{
    private Restaurant restaurant;
    public Chef(Restaurant restaurant){
        this.restaurant = restaurant;
    }
    @Override
    public void run() {
        restaurant.put();
    }
}
class Waiter extends Thread{
    private Restaurant restaurant;
    public Waiter(Restaurant restaurant){
        this.restaurant = restaurant;
    }
    @Override
    public void run() {
        restaurant.get();
    }
}
public class Test {
    public static void main(String[] args) {
        Restaurant restaurant = new Restaurant();
        Chef produce = new Chef(restaurant);
        Waiter consumer = new Waiter(restaurant);
        produce.start();
        consumer.start();
    }
}