Redis+MySQL实现酒店预订功能

酒店预订从实际业务上分析是一个较复杂的功能实现，并不能是简单的增删查改。

涉及并发、一致性等问题。

技术选型：

• Redis
• MySQL

配置Redis

// 配置连接信息

略...

// 配置Redis序列化,不自己配置序列化可能会发生因序列化冲突而造成的错误

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
    RedisTemplate<String, Object> template = new RedisTemplate<>();
    template.setConnectionFactory(connectionFactory);

    //string
    template.setKeySerializer(new StringRedisSerializer());
    template.setValueSerializer(new StringRedisSerializer());
    //Hash
    template.setHashKeySerializer(new StringRedisSerializer());
    template.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());
    template.setDefaultSerializer(new GenericJackson2JsonRedisSerializer());
    template.setStringSerializer(new StringRedisSerializer());
    return template;
    }

配置MySQL

//
// 略...

具体实现

public String userReserve(String userName, Integer hotelId, Integer roomId) {
    String orderNum = UUID.randomUUID().toString();
    if(StringUtils.isAnyBlank(userName)){
        throw new BusinessException(BusinessErrorEnum.PARAMS_ERROR,"用户名不能为空");
    }
    // key-orderNum  value-userName
    if(hotelId == null || roomId == null){
        throw new BusinessException(BusinessErrorEnum.PARAMS_ERROR,"酒店Id和房间ID不能为空");
    }
    redisTemplate.opsForValue().set(orderNum,userName);
    redisTemplate.expire(orderNum,15, TimeUnit.MINUTES);
    SqlSession sqlSession = getSqlSessionFactory().openSession(false);
    Room room = null;
    boolean success = false;

    // SQL事务
    try{
        room = roomMapper.selectRoom(hotelId, roomId);
        if (room==null){
            throw new BusinessException(BusinessErrorEnum.SYSTEM_ERROR,"房间已被其他人预订,事务回滚");
        }
        boolean booked = roomMapper.setReserved(hotelId, roomId,userName, orderNum);
        sqlSession.commit();
        success = true;
    }catch(BusinessException e){
        // 事务回滚
        sqlSession.rollback();
        log.error("事务回滚----"+"预定失败,已被预订"+e.getMessage());
    }finally {
        sqlSession.close();
    }
    if(success){
        // 预订成功
        if(redisTemplate.hasKey(orderNum)){
            // 用户还未取消
            return room.toString();
        }else {
            // 用户已取消
            roomMapper.cancelByOrderNum(orderNum);
            throw new BusinessException(BusinessErrorEnum.NULL_ERROR,"用户已取消订单");
        }
    }else {
        roomMapper.cancelByOrderNum(orderNum);
        // 预订失败
        if(redisTemplate.hasKey(orderNum)){
            redisTemplate.expire(orderNum,0, TimeUnit.MINUTES);
            throw new BusinessException(BusinessErrorEnum.SYSTEM_ERROR,"预订失败");
        }else {
            // 用户已取消
            throw new BusinessException(BusinessErrorEnum.NULL_ERROR,"用户已取消订单");
        }
    }
}