Redis 分布式锁 RedisTemplate 实现

1、配置redis序列化

@Configuration
public class RedisConfig {
    @Bean
    public <T> RedisTemplate<String, T> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<String, T> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        //非final类型的对象，把对象类型也序列化进去，以便反序列化推测正确的类型
        objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        //null字段不显示
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        //POJO无public属性或方法时不报错
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        jackson2JsonRedisSerializer.setObjectMapper(objectMapper);
        redisTemplate.setKeySerializer(redisSerializer);
        redisTemplate.setValueSerializer(jackson2JsonRedisSerializer);
        redisTemplate.setHashValueSerializer(jackson2JsonRedisSerializer);
        redisTemplate.setHashKeySerializer(redisSerializer);
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }
}

2、包含key和requestid的实体类

@Getter
@Setter
@Builder
public class RedisLockEntity {
    private String lockKey;
    private String requestId;
}

3、加锁解锁的工具类

@Service
@Slf4j
public class RedisService {
    @Autowired
    private RedisTemplate redisTemplate;

    /**
     * 加锁，自旋重试三次
     *
     * @param redisLockEntity 锁实体
     * @return
     */
    public boolean lock(RedisLockEntity redisLockEntity) {
        boolean locked = false;
        int tryCount = 3;
        while (!locked && tryCount > 0) {
            locked = redisTemplate.opsForValue().setIfAbsent(redisLockEntity.getLockKey(), redisLockEntity.getRequestId(), 2, TimeUnit.MINUTES);
            tryCount--;
            try {
                Thread.sleep(300);
            } catch (InterruptedException e) {
                log.error("线程被中断" + Thread.currentThread().getId(), e);
            }
        }
        return locked;
    }

    /**
     * 非原子解锁，可能解别人锁，不安全
     *
     * @param redisLockEntity
     * @return
     */
    public boolean unlock(RedisLockEntity redisLockEntity) {
        if (redisLockEntity == null || redisLockEntity.getLockKey() == null || redisLockEntity.getRequestId() == null)
            return false;
        boolean releaseLock = false;
        String requestId = (String) redisTemplate.opsForValue().get(redisLockEntity.getLockKey());
        if (redisLockEntity.getRequestId().equals(requestId)) {
            releaseLock = redisTemplate.delete(redisLockEntity.getLockKey());
        }
        return releaseLock;
    }

    /**
     * 使用lua脚本解锁，不会解除别人锁
     *
     * @param redisLockEntity
     * @return
     */
    public boolean unlockLua(RedisLockEntity redisLockEntity) {
        if (redisLockEntity == null || redisLockEntity.getLockKey() == null || redisLockEntity.getRequestId() == null)
            return false;
        DefaultRedisScript<Long> redisScript = new DefaultRedisScript();
        //用于解锁的lua脚本位置
        redisScript.setLocation(new ClassPathResource("unlock.lua"));
        redisScript.setResultType(Long.class);
        //没有指定序列化方式，默认使用上面配置的
        Object result = redisTemplate.execute(redisScript, Arrays.asList(redisLockEntity.getLockKey()), redisLockEntity.getRequestId());
        return result.equals(Long.valueOf(1));
    }

}

4、用于解锁的lua脚本(放于resources下面)

文件名：unlock.lua

if redis.call('get',KEYS[1]) == ARGV[1] then
    return redis.call('del',KEYS[1])
else
    return 0
end