ReentrantReadWriteLock模拟JVM本地缓存案例

偏执的太偏执、 2023-06-21 03:58 21阅读 0赞

### 一、案例代码 ###

public class ReadLockAndWriteLockTest {
        //存储数据
        private volatile Map<String,String> map=new HashMap<>();
        //读写锁
        private ReentrantReadWriteLock readWriteLock=new ReentrantReadWriteLock();
        //写入锁
        private WriteLock writeLock=readWriteLock.writeLock();
        //读取锁
        private ReadLock readLock=readWriteLock.readLock();
    
        //添加元素
        public void put(String key,String value){
            try {
                writeLock.lock();
                System.out.println("写入开始数据开始，key："+key+",value:"+value);
                map.put(key,value);
                System.out.println("写入开始数据结束，key："+key+",value:"+value);
            } finally {
                writeLock.unlock();
            }
        }
    
        //读取元素
        public  String get(String key){
            try {
                readLock.lock();
                System.out.println("读数据开始，key："+key);
                String value = map.get(key);
                System.out.println("读数据开始，key："+key+",value:"+value);
                return  value;
            } catch (Exception e) {
                return null;
            } finally {
               readLock.unlock();
            }
        }
    
        public static void main(String[] args) {
            ReadLockAndWriteLockTest readLockAndWriteLockTest=new ReadLockAndWriteLockTest();
            //写线程
            Thread writeThread=new Thread(()->{
                for (int i = 0; i < 10; i++) {
                    readLockAndWriteLockTest.put(i+"",i+"");
                }
            });
            writeThread.start();
            //读线程
            Thread readThread=new Thread(()->{
                for (int i = 0; i < 10; i++) {
                    readLockAndWriteLockTest.get(i+"");
                }
            });
            readThread.start();
        }
    
    }

### 二、测试结果 ###

未加锁时：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70][]

加读写锁以后：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191211110408854.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191211110453861.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3htMzkzMzkyNjI1,size_16,color_FFFFFF,t_70