016Redis的使用处理并发，分布式锁

傷城~ 2022-03-07 14:50 190阅读 0赞

使用redis每秒可支持十几万的并发

@Component
    @Slf4j
    public class RedisLLock {
    
        @Autowired
        private StringRedisTemplate redisTemplate;
    
        /**
         *  加锁
         * @param key
         * @param value
         * @return
         */
        public  boolean lock(String key,String value){
            if(redisTemplate.opsForValue().setIfAbsent(key, value)){
                return  true;
            }
            String currentValue =redisTemplate.opsForValue().get(key);
            //如果锁过期
            if (!StringUtils.isEmpty(currentValue)
                    && Long.parseLong(currentValue)<System.currentTimeMillis()){
                //获取上一个锁的时间
                String oldValue =redisTemplate.opsForValue().getAndSet(key, value);
                if (!StringUtils.isEmpty(oldValue)&& oldValue.equals(currentValue)){
                    return  true;
                }
            }
            return  false;
        }
    
        /**
         *  解锁
         * @param key
         * @param value
         */
        public void unlock(String key ,String value){
            try {
                String currentValue =redisTemplate.opsForValue().get(key);
                if(!StringUtils.isEmpty(currentValue)&&currentValue.equals(value)){
                    redisTemplate.opsForValue().getOperations().delete(key);
                }
            }catch (Exception e){
                log.error("【redis分布式锁】解锁异常,{}",e);
            }
        }
    
    }

操作：

private  static final   Integer TIMEOUT = 10*1000;
    
    @Autowired
    private  RedisLLock redisLLock;
        
    @Transactional
    public OrderDTO buy(OrderDTO orderDTO) {
    
        //加锁
        long time = System.currentTimeMillis()+ TIMEOUT;
        if (!redisLLock.lock(orderDTO.getOrderId(),String.valueOf(time))){
            throw  new SellException(101,"哎哟，换个姿势再来~~");
        }
        //具体 操作
    
        //解锁
        redisLLock.unlock(orderDTO.getOrderId(),String.valueOf(time));    
        
    }