基于SpringBoot+Redis实现分布式锁

<dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
   </dependency>
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-redis</artifactId>
   </dependency>
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter</artifactId>
   </dependency>
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
   </dependency>
   <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
   </dependency>
   <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>fastjson</artifactId>
       <version>1.2.72</version>
   </dependency>
   <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
   </dependency>

@Slf4j
@Component
public class RedisLockUtils {
    @Resource
    private RedisTemplate redisTemplate;
    private static Map<String, LockInfo> lockInfoMap = new ConcurrentHashMap<>();
    private static final Long SUCCESS = 1L;
    public static class LockInfo {
        private String key;
        private String value;
        private int expireTime;
        //更新时间
        private long renewalTime;
        //更新间隔
        private long renewalInterval;
        public static LockInfo getLockInfo(String key, String value, int expireTime) {
            LockInfo lockInfo = new LockInfo();
            lockInfo.setKey(key);
            lockInfo.setValue(value);
            lockInfo.setExpireTime(expireTime);
            lockInfo.setRenewalTime(System.currentTimeMillis());
            lockInfo.setRenewalInterval(expireTime * 2000 / 3);
            return lockInfo;
        }
        public String getKey() {
            return key;
        }
        public void setKey(String key) {
            this.key = key;
        }
        public String getValue() {
            return value;
        }
        public void setValue(String value) {
            this.value = value;
        }
        public int getExpireTime() {
            return expireTime;
        }
        public void setExpireTime(int expireTime) {
            this.expireTime = expireTime;
        }
        public long getRenewalTime() {
            return renewalTime;
        }
        public void setRenewalTime(long renewalTime) {
            this.renewalTime = renewalTime;
        }
        public long getRenewalInterval() {
            return renewalInterval;
        }
        public void setRenewalInterval(long renewalInterval) {
            this.renewalInterval = renewalInterval;
        }
    }
    /**
     * 使用lua脚本更新redis锁的过期时间
     * @param lockKey
     * @param value
     * @return 成功返回true, 失败返回false
     */
    public boolean renewal(String lockKey, String value, int expireTime) {
        String luaScript = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('expire', KEYS[1], ARGV[2]) else return 0 end";
        DefaultRedisScript<Boolean> redisScript = new DefaultRedisScript<>();
        redisScript.setResultType(Boolean.class);
        redisScript.setScriptText(luaScript);
        List<String> keys = new ArrayList<>();
        keys.add(lockKey);
        Object result = redisTemplate.execute(redisScript, keys, value, expireTime);
        log.info("更新redis锁的过期时间：{}", result);
        return (boolean) result;
    }
    /**
     * @param lockKey    锁
     * @param value      身份标识（保证锁不会被其他人释放）
     * @param expireTime 锁的过期时间（单位：秒）
     * @return 成功返回true, 失败返回false
     */
    public boolean lock(String lockKey, String value, long expireTime) {
        return redisTemplate.opsForValue().setIfAbsent(lockKey, value, expireTime, TimeUnit.SECONDS);
    }
    /**
     * redisTemplate解锁
     * @param key
     * @param value
     * @return 成功返回true, 失败返回false
     */
    public boolean unlock2(String key, String value) {
        Object currentValue = redisTemplate.opsForValue().get(key);
        boolean result = false;
        if (StringUtils.isNotEmpty(String.valueOf(currentValue)) && currentValue.equals(value)) {
            result = redisTemplate.opsForValue().getOperations().delete(key);
        }
        return result;
    }
    /**
     * 定时去检查redis锁的过期时间
     */
    @Scheduled(fixedRate = 5000L)
    @Async("redisExecutor")
    public void renewal() {
        long now = System.currentTimeMillis();
        for (Map.Entry<String, LockInfo> lockInfoEntry : lockInfoMap.entrySet()) {
            LockInfo lockInfo = lockInfoEntry.getValue();
            if (lockInfo.getRenewalTime() + lockInfo.getRenewalInterval() < now) {
                renewal(lockInfo.getKey(), lockInfo.getValue(), lockInfo.getExpireTime());
                lockInfo.setRenewalTime(now);
                log.info("lockInfo {}", JSON.toJSONString(lockInfo));
            }
        }
    }
    /**
     * 分布式锁设置单独线程池
     * @return
     */
    @Bean("redisExecutor")
    public Executor redisExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(1);
        executor.setMaxPoolSize(1);
        executor.setQueueCapacity(1);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("redis-renewal-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardOldestPolicy());
        return executor;
    }
}

@Configuration
public class RedisConfig {
    @Bean
    public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) throws Exception {
        RedisTemplate redisTemplate = new RedisTemplate();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        // 创建 序列化类
        GenericToStringSerializer genericToStringSerializer = new GenericToStringSerializer(Object.class);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(genericToStringSerializer);
        return redisTemplate;
    }
}

@RestController
public class IndexController {
    @Resource
    private RedisTemplate redisTemplate;
    @Autowired
    private RedisLockUtils redisLock;
    @RequestMapping("/deduct-stock")
    public String deductStock() {
        String productId = "product001";
        System.out.println("---------------->>>开始扣减库存");
        String key = productId;
        String requestId = productId + Thread.currentThread().getId();
        try {
            boolean locked = redisLock.lock(key, requestId, 10);
            if (!locked) {
                return "error";
            }
            //执行业务逻辑
            //System.out.println("---------------->>>执行业务逻辑:"+appTitle);
            int stock = Integer.parseInt(redisTemplate.opsForValue().get("product001-stock").toString());
            int currentStock = stock-1;
            redisTemplate.opsForValue().set("product001-stock",currentStock);
            try {
                Random random = new Random();
                Thread.sleep(random.nextInt(3) *1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("---------------->>>扣减库存结束:current stock:" + currentStock);
            return "success,current stock:" + currentStock;
        } finally {
            redisLock.unlock2(key, requestId);
        }
    }
}