基于Lock+Condition实现生产者消费者模式

代码语言：javascript复制

package demo;

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

//产品仓库类
class Storage {
    private int maxSize; // 缓冲区大小
    private List<Object> buffer;
    private final Lock lock = new ReentrantLock(true);
    private final Condition condition = lock.newCondition();

    public Storage(int maxSize){
        this.maxSize =maxSize;
        buffer=new ArrayList<>();
    }
    // 写操作，生产一个产品
    public void put() {
        try {
            lock.lock();
            while (buffer.size() == maxSize) {
                System.out.println(Thread.currentThread().getName()   " Producer wait! ");
                condition.await();
            }
            buffer.add(new Object());
            System.out.println(Thread.currentThread().getName()   "：存入一个产品，现在产品数="   buffer.size());
            condition.signalAll(); // 通知消费者
        } catch (InterruptedException e) {
            System.out.println(e);
        } finally {
            // 释放锁
            lock.unlock();
        }
    }

    // 读操作，消费一个产品
    public void get() {
        lock.lock();// 加锁
        try {
            while (buffer.isEmpty()) { // 缓冲区空了
                System.out.println(Thread.currentThread().getName()   " Consumer wait！");
                condition.await();
            }
            // 消费一个产品
            buffer.remove(0); // 从链表头部移除一个
            System.out.println(Thread.currentThread().getName()   "：取出一个产品，现在产品数="   buffer.size());
            condition.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}
//生产者
class Producer implements Runnable {
    private Storage storage;
    public Producer(Storage storage) {
        this.storage = storage;
    }
    @Override
    public void run() {
        storage.put();
    }
}
//消费者
class Consumer implements Runnable {
    private Storage storage;
    public Consumer(Storage storage) {
        this.storage = storage;
    }

    @Override
    public void run() {
        storage.get();
    }
}

public class ProducerConsumerDemo {

    public static void main(String[] args) {
        Storage storage=new Storage(5);
        //10个生产者
        for(int i=0;i<10;i  ){
            new Thread(new Producer(storage)).start();
        }
        //5个消费者
        for(int i=0;i<5;i  ){
            new Thread(new Consumer(storage)).start();
        }
    }

}

运行结果

代码语言：javascript复制

Thread-0：存入一个产品，现在产品数=1
Thread-1：存入一个产品，现在产品数=2
Thread-3：存入一个产品，现在产品数=3
Thread-2：存入一个产品，现在产品数=4
Thread-4：存入一个产品，现在产品数=5
Thread-5 Producer wait! 
Thread-6 Producer wait! 
Thread-7 Producer wait! 
Thread-8 Producer wait! 
Thread-9 Producer wait! 
Thread-10：取出一个产品，现在产品数=4
Thread-5：存入一个产品，现在产品数=5
Thread-6 Producer wait! 
Thread-7 Producer wait! 
Thread-8 Producer wait! 
Thread-9 Producer wait! 
Thread-11：取出一个产品，现在产品数=4
Thread-12：取出一个产品，现在产品数=3
Thread-6：存入一个产品，现在产品数=4
Thread-7：存入一个产品，现在产品数=5
Thread-8 Producer wait! 
Thread-9 Producer wait! 
Thread-13：取出一个产品，现在产品数=4
Thread-14：取出一个产品，现在产品数=3
Thread-8：存入一个产品，现在产品数=4
Thread-9：存入一个产品，现在产品数=5

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