一、概述

ReentrantReadWriteLock是ReadWriteLock的一个子类，具有读锁和写锁的双重功能，通常用于做缓存。

二、案例代码

2.1、ReentrantReadWriteLockCache

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 17:57* @Description: 使用ReentrantReadWriteLock实现缓存的功能*/
public class ReentrantReadWriteLockCache {private volatile Map<String, Object> map = new HashMap<>();private ReadWriteLock rwLock = new ReentrantReadWriteLock();/*** 写数据* @param key* @param value*/public void put(String key, Object value) {rwLock.writeLock().lock();try {System.out.println(Thread.currentThread().getName() + "\t正在写" + key);// 线程休眠，单位：毫秒try {TimeUnit.MILLISECONDS.sleep(300);} catch (Exception e) {e.printStackTrace();}map.put(key, value);System.out.println(Thread.currentThread().getName() + "\t写完了" + key);System.out.println();} catch (Exception e) {e.printStackTrace();} finally {rwLock.writeLock().unlock();}}/*** 读数据* @param key* @return*/public Object get(String key) {rwLock.readLock().lock();Object result = null;try {System.out.println(Thread.currentThread().getName() + "\t正在读" + key);// 线程休眠，单位：毫秒try {TimeUnit.MILLISECONDS.sleep(300);} catch (Exception e) {e.printStackTrace();}result = map.get(key);System.out.println(Thread.currentThread().getName() + "\t读完了" + result);} catch (Exception e) {e.printStackTrace();} finally {rwLock.readLock().unlock();}return result;}
}

2.2、ReentrantReadWriteLockMainApp

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 18:00* @Description:*/
public class ReentrantReadWriteLockMainApp {public static void main(String[] args) {ReentrantReadWriteLockCache cache = new ReentrantReadWriteLockCache();for (int i = 1; i <= 5; i++) {final int number = i;new Thread(() -> {try {cache.put(String.valueOf(number),number);} catch (Exception e) {e.printStackTrace();}}, String.valueOf(i)).start();}for (int i = 1; i <= 5; i++) {final int number = i;new Thread(() -> {try {cache.get(String.valueOf(number));} catch (Exception e) {e.printStackTrace();}}, String.valueOf(i)).start();}}}