Java生產(chǎn)者消費(fèi)者的三種實(shí)現(xiàn)方式

更新時(shí)間：2024年07月04日 10:39:34 作者：xindoo

這篇文章主要介紹了Java生產(chǎn)者消費(fèi)者的三種實(shí)現(xiàn)方式,具有很好的參考價(jià)值,希望對(duì)大家有所幫助,如有錯(cuò)誤或未考慮完全的地方,望不吝賜教

Java生產(chǎn)者消費(fèi)者的實(shí)現(xiàn)

Java生產(chǎn)者消費(fèi)者是最基礎(chǔ)的線程同步問題，java崗面試中還是很容易遇到的，之前沒寫過多線程的代碼，面試中被問到很尬啊，面完回來惡補(bǔ)下。

在網(wǎng)上查到大概有5種生產(chǎn)者消費(fèi)者的寫法，分別如下。

用synchronized對(duì)存儲(chǔ)加鎖，然后用object原生的wait() 和 notify()做同步。
用concurrent.locks.Lock，然后用condition的await() 和signal()做同步。
直接使用concurrent.BlockingQueue。
使用PipedInputStream/PipedOutputStream。
使用信號(hào)量semaphore。

我的理解，生產(chǎn)者消費(fèi)者模式，其實(shí)只要保證在存儲(chǔ)端同一時(shí)刻只有一個(gè)線程讀或?qū)懢筒粫?huì)有問題，然后再去考慮線程同步。

方法1 2 5都比較類似，都是加鎖來限制同一時(shí)刻只能有一個(gè)讀或?qū)?。而方? 4其實(shí)是在存儲(chǔ)內(nèi)部去保證讀和寫的唯一的，最低層肯定還是通過鎖機(jī)制來實(shí)現(xiàn)的，java底層代碼都封裝好了而已?！　?/p>

我自己嘗試寫了下前三種，代碼如下：　

synchronized版本

import java.util.LinkedList;
import java.util.Queue;

public class ProducerAndConsumer {
    private final int MAX_LEN = 10;
    private Queue<Integer> queue = new LinkedList<Integer>();
    class Producer extends Thread {
        @Override
        public void run() {
            producer();
        }
        private void producer() {
            while(true) {
                synchronized (queue) {
                    while (queue.size() == MAX_LEN) {
                        queue.notify();
                        System.out.println("當(dāng)前隊(duì)列滿");
                        try {
                            queue.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    queue.add(1);
                    queue.notify();
                    System.out.println("生產(chǎn)者生產(chǎn)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    class Consumer extends Thread {
        @Override
        public void run() {
            consumer();
        }
        private void consumer() {
            while (true) {
                synchronized (queue) {
                    while (queue.size() == 0) {
                        queue.notify();
                        System.out.println("當(dāng)前隊(duì)列為空");
                        try {
                            queue.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    queue.poll();
                    queue.notify();
                    System.out.println("消費(fèi)者消費(fèi)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    public static void main(String[] args) {
        ProducerAndConsumer pc = new ProducerAndConsumer();
        Producer producer = pc.new Producer();
        Consumer consumer = pc.new Consumer();
        producer.start();
        consumer.start();
    }
}

lock版實(shí)現(xiàn)，使用了condition做線程之間的同步

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

/**
 * version 1 doesn't use synchronized to improve performance
 */
public class ProducerAndConsumer1 {
    private final int MAX_LEN = 10;
    private Queue<Integer> queue = new LinkedList<Integer>();
    private final Lock lock = new ReentrantLock();
    private final Condition condition = lock.newCondition();
    class Producer extends Thread {
        @Override
        public void run() {
            producer();
        }
        private void producer() {
            while(true) {
                lock.lock();
                try {
                    while (queue.size() == MAX_LEN) {
                        System.out.println("當(dāng)前隊(duì)列滿");
                        try {
                            condition.await();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    queue.add(1);
                    condition.signal();
                    System.out.println("生產(chǎn)者生產(chǎn)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                } finally {
                    lock.unlock();
                }
            }
        }
    }
    class Consumer extends Thread {
        @Override
        public void run() {
            consumer();
        }
        private void consumer() {
            while (true) {
                lock.lock();
                try {
                    while (queue.size() == 0) {
                        System.out.println("當(dāng)前隊(duì)列為空");
                        try {
                            condition.await();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    queue.poll();
                    condition.signal();
                    System.out.println("消費(fèi)者消費(fèi)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                } finally {
                    lock.unlock();
                }
            }
        }
    }
    public static void main(String[] args) {
        ProducerAndConsumer pc = new ProducerAndConsumer();
        Producer producer = pc.new Producer();
        Consumer consumer = pc.new Consumer();
        producer.start();
        consumer.start();
    }
}

BlockingQueue版實(shí)現(xiàn)

import java.util.Random;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;


public class ProducerAndConsumer {
    private BlockingQueue<Integer> queue = new LinkedBlockingQueue<Integer>(10);
    class Producer extends Thread {
        @Override
        public void run() {
            producer();
        }
        private void producer() {
            while(true) {
                try {
                    queue.put(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("生產(chǎn)者生產(chǎn)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                try {
                    Thread.sleep(new Random().nextInt(1000)+500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    class Consumer extends Thread {
        @Override
        public void run() {
            consumer();
        }
        private void consumer() {
            while (true) {
                try {
                    queue.take();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("消費(fèi)者消費(fèi)一條任務(wù)，當(dāng)前隊(duì)列長度為" + queue.size());
                try {
                    Thread.sleep(new Random().nextInt(1000)+500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    public static void main(String[] args) {
        ProducerAndConsumer pc = new ProducerAndConsumer();
        Producer producer = pc.new Producer();
        Consumer consumer = pc.new Consumer();
        producer.start();
        consumer.start();
    }
}