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ReentrantLock + Condition 实现

package org.example;

import java.util.LinkedList;
import java.util.Queue;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class ProducerConsumer {
    private Queue<String> queue = new LinkedList<>();
    
    private static final Integer BUFFER_SIZE = 3;
    private final ReentrantLock lock = new ReentrantLock();
    private final Condition producerCondition = lock.newCondition();
    private final Condition consumerCondition = lock.newCondition();

    public void produce() {
        lock.lock();
        while (queue.size() >= BUFFER_SIZE) {
            try {
                producerCondition.await();
            } catch (InterruptedException e) {

            }
        }
        queue.add(Thread.currentThread().getName());
        System.out.println("[Producer]" + Thread.currentThread().getName());
        consumerCondition.signal();
        lock.unlock();
    }

    public void consume() {

        lock.lock();
        while (queue.isEmpty()) {
            try {
                consumerCondition.await();
            } catch (InterruptedException e) {

            }
        }
        String elem = queue.poll();
        System.out.printf("[Consumer] Thread: %s, consume: %s%n\n", Thread.currentThread().getName(), elem);
        producerCondition.signal();
        lock.unlock();
    }

    static class Producer implements Runnable {
        ProducerConsumer pc;

        public Producer(ProducerConsumer pc) {
            this.pc = pc;
        }

        @Override
        public void run() {
            int times = 3;
            while (times-- > 0) {
                pc.produce();
            }
        }
    }

    static class Consumer implements Runnable {
        ProducerConsumer pc;

        public Consumer(ProducerConsumer pc) {
            this.pc = pc;
        }

        @Override
        public void run() {
            int times = 3;
            while (times-- > 0) {
                pc.consume();
            }
        }
    }

    public static void main(String[] args) {
        ProducerConsumer producerConsumer = new ProducerConsumer();
        Producer producer = new Producer(producerConsumer);
        Consumer consumer = new Consumer(producerConsumer);
        Thread t1 = new Thread(producer);
        Thread t2 = new Thread(producer);
        Thread t3 = new Thread(consumer);
        Thread t4 = new Thread(consumer);
        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }

}

还有BlockingQueue实现，也是线程安全的