Java 并发编程ReadWriteLock

偏执的太偏执、 2023-10-07 08:29 2阅读 0赞

## `一、ReadWriteLock` ##

> `ReadWriteLock` 有一个实现类 `ReentrantReadWriteLock` 可以用来创建读写锁。在学习之前可以先学习一下  
> [ReentrantLock][]。  
>   
> `ReadWriteLock`特性：
> 
>  *  支持公平锁与非公平锁；
>  *  可重入；
>  *  支持锁降级（写锁 -> 读锁），写锁降级成读锁，并不会自动释放当前线程获取的写锁，仍然需要显示的释放，否则别的线程永远也获取不到写锁；
>  *  读写锁之间是互斥关系；
>  *  写锁与写锁之间是互斥关系；
>  *  读锁与读锁之间可以同时进行。

## `二、是例` ##

public class Test {
        
    
        public static void main(String[] args) throws Exception {
        
            ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
            Lock writeLock = readWriteLock.writeLock();
            Lock readLock = readWriteLock.readLock();
    
            Runnable runnable1 = new Runnable() {
        
                @Override
                public void run() {
        
                    writeLock.lock();
    
                    System.out.println(Thread.currentThread().getName() + "开始写入数据....");
    
                    try {
        
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
        
                        e.printStackTrace();
                    }
    
                    System.out.println(Thread.currentThread().getName() + "写入完成!");
                    writeLock.unlock();
                }
            };
    
            Runnable runnable2 = new Runnable() {
        
                @Override
                public void run() {
        
                    readLock.lock();
    
                    System.out.println(Thread.currentThread().getName() + "开始读取数据。。。");
    
    
                    try {
        
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
        
                        e.printStackTrace();
                    }
    
    
                    System.out.println(Thread.currentThread().getName() + "读取数据完成");
    
                    readLock.unlock();
    
                }
            };
    
            Thread thread1 = new Thread(runnable1);
            Thread thread2 = new Thread(runnable2);
            thread2.start();
            thread1.start();
    
        }
    
    }

[ReentrantLock]: https://blog.csdn.net/qq_27870421/article/details/104021670