Redisson 的分布式锁

参考：https://www.cnblogs.com/zgq7/p/14746128.html

一、Redisson 的使用

1、Redisson 的简单使用

（1）引入maven坐标；

<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.13.4</version>
</dependency>

 

（2）增加配置文件，将Redisson注入到容器中；

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@Configuration public class RedissonConfig {        @Bean     public Redisson redisson() {         Config config = new Config();         //单机版         //config.useSingleServer().setAddress("redis://192.168.1.1:8001").setDatabase(0);            //集群版         config.useClusterServers()                 .addNodeAddress("redis://192.168.1.1:8001")                 .addNodeAddress("redis://192.168.1.1:8002")                 .addNodeAddress("redis://192.168.1.2:8001")                 .addNodeAddress("redis://192.168.1.2:8002")                 .addNodeAddress("redis://192.168.1.3:8001")                 .addNodeAddress("redis://192.168.1.3:8002");         return (Redisson) Redisson.create(config);     } }

 

（3）分布式锁的实现

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@Service public class RedisLockDemo {     @Autowired     private StringRedisTemplate redisTemplate;        @Autowired     private Redisson redisson;        public String deduceStock() {         String lockKey = "lockKey";         RLock redissonLock = redisson.getLock(lockKey);            try {             //加锁, 实现锁续命的功能(加锁成功，后台启动一个timer, 默认每10s检测一次是否持有锁，若持有锁则继续续命30s)             redissonLock.lock();                //------ 执行业务逻辑 ----start------             int stock = Integer.valueOf(redisTemplate.opsForValue().get("stock"));             if (stock > 0) {                 int newStock = stock - 1;                 //执行业务操作减库存                 redisTemplate.opsForValue().set("stock", newStock + "");                 System.out.println("扣减库存成功, 剩余库存:" + newStock);             } else {                 System.out.println("库存已经为0，不能继续扣减");             }             //------ 执行业务逻辑 ----end------         } finally {             //解锁             redissonLock.unlock();         }         return "success";     } }

 

2、Redisson 的几种加锁方式

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/*  *  (1) T1加锁成功: 会添加TimerTask; 每10s执行一次检测锁是否为当前线程占用, 若占用, 则将key超时时间重置为30s;  *  (2) T2加锁失败后会不停的去重试;  */ redissonLock.lock();   /*  *  (1) T1加锁成功后直接返回, 20s后锁自动过期; (没有watch dog)  *  (2) T2加锁失败后会不停的去重试;  */ redissonLock.lock(20, TimeUnit.SECONDS);   /*  *  (1) T1尝试加锁成功, 返回true; 会添加TimerTask; 每10s执行一次检测锁是否为当前线程占用, 若占用, 则将key超时时间重置为30s;  *  (2) T2没有获取到锁会不停的去重试, 在50s后停止重试, 返回false;  */ boolean isGetLock = redissonLock.tryLock(50, TimeUnit.SECONDS);   /*  *  (1) T1尝试加锁成功, 返回true, 锁在20s后自动过期; (没有watch dog)  *  (2) T2尝试加锁失败, 在50s后停止重试, 返回false;  */ boolean isGetLock = redissonLock.tryLock(50, 20, TimeUnit.SECONDS);   //-------------------------------------------------------------   //2. 公平锁 保证 Redisson 客户端线程将以其请求的顺序获得锁 RLock fairLock = redissonClient.getFairLock("fairLock");   //3. 读写锁 没错与JDK中ReentrantLock的读写锁效果一样 RReadWriteLock readWriteLock = redissonClient.getReadWriteLock("readWriteLock"); readWriteLock.readLock().lock(); readWriteLock.writeLock().lock();

 

二、Redisson 的分布式锁原理

 

 Redisson 的加锁和解锁都通过 lua 脚本来处理的；

三、Redisson的分布式锁源码分析