current包下ReentrantReadWriteLock的使用

ReentrantReadWriteLock中可以生产读锁和写锁。

读锁和读锁不互斥，写锁和任何读锁或者写锁都互斥。

demo：读锁和读锁不互斥

public static void main(String[] args) {
    ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();
    final ReentrantReadWriteLock.ReadLock readLock = reentrantReadWriteLock.readLock();
    final ReentrantReadWriteLock.WriteLock writeLock = reentrantReadWriteLock.writeLock();

    for (int i = 0; i < 5; i++) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    readLock.lock();
                    System.out.println(Thread.currentThread().getName() + "  开始读取数据");
                    TimeUnit.SECONDS.sleep(5);
                    System.out.println(Thread.currentThread().getName() + "   读取完毕");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    readLock.unlock();
                }
            }
        }).start();

    }

}

demo读锁和写锁互斥：

public static void main(String[] args) {
    ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();
    final ReentrantReadWriteLock.ReadLock readLock = reentrantReadWriteLock.readLock();
    final ReentrantReadWriteLock.WriteLock writeLock = reentrantReadWriteLock.writeLock();

    for (int i = 0; i < 4; i++) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    readLock.lock();
                    System.out.println(Thread.currentThread().getName() + "  开始读取数据");
                    TimeUnit.SECONDS.sleep(5);
                    System.out.println(Thread.currentThread().getName() + "   读取完毕");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    readLock.unlock();
                }
            }
        }).start();
    }

    new Thread(new Runnable() {
        public void run() {
            try {
                writeLock.lock();
                System.out.println(Thread.currentThread().getName() + "  开始写入数据");
                TimeUnit.SECONDS.sleep(5);
                System.out.println(Thread.currentThread().getName() + "   读取完毕");
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                writeLock.unlock();
            }
        }
    }).start();
}

写锁和写锁互斥：

public static void main(String[] args) {
    ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();
    final ReentrantReadWriteLock.ReadLock readLock = reentrantReadWriteLock.readLock();
    final ReentrantReadWriteLock.WriteLock writeLock = reentrantReadWriteLock.writeLock();

    for (int i = 0; i < 4; i++) {
        new Thread(new Runnable() {
        public void run() {
            try {
                writeLock.lock();
                System.out.println(Thread.currentThread().getName() + "  开始写入数据");
                TimeUnit.SECONDS.sleep(5);
                System.out.println(Thread.currentThread().getName() + "   读取完毕");
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                writeLock.unlock();
            }
        }
    }).start();
    }
    
}

来源：oschina

链接：https://my.oschina.net/u/2250599/blog/552080

标签

读写锁

reentrantreadwritelock

并发

current

java并发