redis实现简单分布式锁

1.redisTemplate实现简单分布式锁

 @AutowiredRedisTemplate redisTemplate;/*** redis分布式锁演示案例，此处使用redisTemplate* @param stockId  此处以扣减库存为例子，stockId代表要扣减库存的商品id,库存数据是提前存在redis的，并和数据库进行同步* @return*/public AjaxResult redisLockDemo(String stockId){//锁前缀final String stock_lock = "stock_lock:";// 生成一个随机唯一的值用于辨别锁的使用对象String clientId = UUID.randomUUID().toString();//此处使用set(k,v,time,unit)来获取锁，确保加锁和设置超时时间是原子操作Boolean lock = redisTemplate.opsForValue().setIfAbsent(stock_lock + stockId, clientId, 10, TimeUnit.MILLISECONDS);if (!lock){//获取锁失败return AjaxResult.error("服务器繁忙，请稍后再试！");}//获取锁成功//执行扣减库存try {int stock = (int) redisTemplate.opsForValue().get(stockId);if (stock > 0){int realStock = stock - 1;// 重新设置库存数据redisTemplate.opsForValue().set(stockId, realStock + "");// .............其他步骤log.info("库存扣减成功{}", stockId);} else {return AjaxResult.error("商品已经被抢光了！");}} finally {//释放锁
//            if (clientId.equals(stringRedisTemplate.opsForValue().get(stock_lock + stockId))){
//                stringRedisTemplate.delete(stock_lock + stockId);
//            }//此处使用lua脚本释放锁，具有原子性String script = "local lockKey = KEYS[1]\n" +"local clientId = ARGV[1]\n" +"local currentHolder = redis.call('GET', lockKey)\n" +"if currentHolder == clientId then\n" +"    redis.call('DEL', lockKey)\n" +"    return true\n" +"else\n" +"    return false\n" +"end";DefaultRedisScript<Boolean> redisScript = new DefaultRedisScript<>(script, Boolean.class);Boolean result = (Boolean) redisTemplate.execute(redisScript, Collections.singletonList(stock_lock + stockId), clientId);if (result != null && result) {log.info("所释放成功");} else {log.info("所释放失败");}}return AjaxResult.success("扣减库存成功！");}

2.redission实现分布式锁

    @AutowiredRedisson redisson; 
/*** redis分布式锁演示案例，redisson* @param stockId  此处以扣减库存为例子，stockId代表要扣减库存的商品id,库存数据是提前存在redis的，并和数据库进行同步* @return*/public AjaxResult redissonLockDemo(String stockId){final String lockKey = "stock_lock:";RLock lock = redisson.getLock(lockKey);lock.lock();try {//执行扣减库存int stock = (int) redisTemplate.opsForValue().get(stockId);if (stock > 0){int realStock = stock - 1;// 重新设置库存数据redisTemplate.opsForValue().set(stockId, realStock + "");// .............其他步骤log.info("库存扣减成功{}", stockId);} else {return AjaxResult.error("商品已经被抢光了！");}}finally {lock.unlock();}return AjaxResult.success("扣减库存成功！");}