ReentranReadWriteLock 使用案例

 ReentranReadWriteLock使用案例

/*** ReentranReadWriteLock 使用案例* 读线程共享* 写线程互斥*/
public class ReentrantReadWriteLockExample {private String news;private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();public String readNews() {lock.readLock().lock();try {// 读线程睡眠1秒, 观察打印时间Thread.sleep(1000);System.out.println(Thread.currentThread().getName() + " " + LocalDateTime.now().format(DateTimeFormatter.ofPattern("hh:mm:ss")) + " is reading the news: " + news);return news;} catch (InterruptedException e) {throw new RuntimeException(e);} finally {lock.readLock().unlock();}}public void writeNews(String updatedNews) {lock.writeLock().lock();try {// 让写线程睡眠两秒,这样可以观察到写线程阻塞Thread.sleep(2000); System.out.println(Thread.currentThread().getName() + " " +  LocalDateTime.now().format(DateTimeFormatter.ofPattern("hh:mm:ss"))  + " is updating the news to: " + updatedNews);news = updatedNews;} catch (InterruptedException e) {throw new RuntimeException(e);} finally {lock.writeLock().unlock();}}public static void main(String[] args) {ReentrantReadWriteLockExample newsData = new ReentrantReadWriteLockExample();// 创建多个读线程for (int i = 0; i < 10; i++) {new Thread(() -> {newsData.readNews();}).start();}// 创建多个写线程for (int i = 0; i < 5; i++) {new Thread(()->{newsData.writeNews("Breaking news: JavaAssistant is awesome!");}).start();}}
}

 输出结果

从结果可以看出，读线程是同时读取了news，而写线程则是一个个的读。

Thread-0 10:11:45 is reading the news: null
Thread-7 10:11:45 is reading the news: null
Thread-6 10:11:45 is reading the news: null
Thread-1 10:11:45 is reading the news: null
Thread-5 10:11:45 is reading the news: null
Thread-3 10:11:45 is reading the news: null
Thread-2 10:11:45 is reading the news: null
Thread-9 10:11:45 is reading the news: null
Thread-4 10:11:45 is reading the news: null
Thread-8 10:11:45 is reading the news: null
Thread-10 10:11:47 is updating the news to: Breaking news: JavaAssistant is awesome!
Thread-11 10:11:49 is updating the news to: Breaking news: JavaAssistant is awesome!
Thread-12 10:11:51 is updating the news to: Breaking news: JavaAssistant is awesome!
Thread-13 10:11:53 is updating the news to: Breaking news: JavaAssistant is awesome!
Thread-14 10:11:55 is updating the news to: Breaking news: JavaAssistant is awesome!