java多线程基础：读写锁_set 读写锁-优快云博客

本文介绍了读写锁的工作原理及其特点，通过示例代码展示了读写锁如何在多线程环境中实现读读不互斥而读写、写写互斥的效果。通过对一个简单的读写演示类的使用，说明了在并发场景下读写锁如何提高程序效率。

读写锁的特点，读读不互斥，读写，写写互斥。

private ReadWriteLock lock = new ReentrantReadWriteLock();

lock.readLock().lock(); //开启读锁

lock.readLock().unlock();//释放读锁

lock.writeLock().lock();//开启写锁

lock.writeLock().unlock();//释放写锁

public class TestReadWriteLock {
    public static void main(String[] args) {
        ReadWriteDemo demo = new ReadWriteDemo();
        for (int i = 0; i < 5; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    demo.set((int)(Math.random()*1000));
                }
            },"write").start();
        }
        for (int i = 0; i < 50; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    demo.get();
                }
            },"read").start();
        }

    }
}
class  ReadWriteDemo{
    private int  num;
    private ReadWriteLock lock = new ReentrantReadWriteLock();

    public void get(){
        lock.readLock().lock();
        try{
            //Thread.sleep(1);
            System.out.println(Thread.currentThread().getName()+" "+num);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.readLock().unlock();
        }
    }

    public void set(int num){
        lock.writeLock().lock();
        try{
            Thread.sleep(1000);
            this.num = num;
            System.out.println(Thread.currentThread().getName()+" "+num);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.writeLock().unlock();
        }
    }
}