Java Thread系列（十）生产者消费者模式
2024-08-28 17:38:41
Java Thread系列（十）生产者消费者模式
生产者消费者问题(producer-consumer problem)，是一个多线程同步问题的经典案例。该问题描述了两个共亨固定大小缓冲区的线程—即所谓的“生产者”和“消费者—在实际运行时会发生的问题。
一、信号灯法
信号灯法实际上就是保证同一时间只有一个线程在操作数据，操作完成后通知其它线程，从而避免死锁。
(1) 生产者
public class Producer implements Runnable {
private Data data;
public Producer(Data data) {
this.data = data;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
data.produce(String.format("product-%s", i));
}
}
}
(2) 消费者
public class Consumer implements Runnable {
private Data data;
public Consumer(Data data) {
this.data = data;
}
@Override
public void run() {
while (true) {
data.consume();
}
}
}
(3) 数据
public class Data {
private String data;
// flag = true 生产者生产，消费者等待，生产完毕后通知消费者消费
// flag = false 消费者消费，生产者等待，消费完毕后通知生产者生产
private boolean flag = true;
public synchronized void consume() {
if (flag) {
try {
wait();
} catch (InterruptedException e) {
;
}
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
;
}
notify();
System.out.println("消费者消费：" + getData());
flag = true;
}
public synchronized void produce(String data) {
if (!flag) {
try {
wait();
} catch (InterruptedException e) {
;
}
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
;
}
notify();
System.out.println("生产者生产：" + data);
setData(data);
flag = false;
}
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
}
(4) 测试
public static void main(String[] args) {
Data data = new Data();
new Thread(new Producer(data)).start();
new Thread(new Consumer(data)).start();
}
二、容器法
(1) Producter
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
public class Producter implements Runnable {
private BlockingQueue<Data> data;
//用于生成id
private static AtomicInteger count = new AtomicInteger(0);
public Producter(BlockingQueue<Data> data) {
this.data = data;
}
public Producter() { }
@Override
//生产者生产数据
public void run() {
try {
Thread.sleep(2000);
int id = count.incrementAndGet();
if (!this.data.offer(new Data(id, "data-" + id), 2, TimeUnit.SECONDS)) {
System.out.printf("%s生产：data-%s失败\n", Thread.currentThread().getName(), id);
} else {
System.out.printf("%s生产：data-%s\n", Thread.currentThread().getName(), id);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
(2) Consumer
import java.util.concurrent.BlockingQueue;
public class Consumer implements Runnable {
private BlockingQueue<Data> data;
public Consumer(BlockingQueue<Data> data) {
this.data = data;
}
public Consumer() { }
@Override
//消费者消费数据
public void run() {
Data d = null;
try {
d = this.data.take();
System.out.printf("%s消费：%s\n", Thread.currentThread().getName(), d.getName());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public class Data {
private int id;
private String name;
}
(3) 测试
LinkedBlockingQueue<Data> data = new LinkedBlockingQueue<Data>();
Producter p1 = new Producter(data);
Producter p2 = new Producter(data);
Producter p3 = new Producter(data);
Consumer c1 = new Consumer(data);
Consumer c2 = new Consumer(data);
Consumer c3 = new Consumer(data);
ExecutorService pool = Executors.newCachedThreadPool();
pool.execute(p1);
pool.execute(p2);
pool.execute(p3);
pool.execute(c1);
pool.execute(c2);
pool.execute(c3);
pool.shutdown();
每天用心记录一点点。内容也许不重要，但习惯很重要！
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