캐싱 Redis + Spring Cache

# application.properties
spring.data.redis.host=localhost
spring.data.redis.port=6379
spring.cache.type=redis
spring.cache.redis.time-to-live=3600000 # 1시간

// CacheConfig.java
@Configuration
@EnableCaching
public class CacheConfig {
    @Bean
    public RedisCacheManager cacheManager(RedisConnectionFactory factory) {
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
            .entryTtl(Duration.ofHours(1))
            .serializeValuesWith(RedisSerializationContext
                .SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));
        return RedisCacheManager.builder(factory)
            .cacheDefaults(config).build();
    }
}

// UserService.java — 캐시 적용
@Service
public class UserService {
    // 캐시에 없으면 DB 조회 후 저장
    @Cacheable(value = "users", key = "#id")
    public UserDto findById(Long id) {
        return userRepository.findById(id).map(UserDto::from)
            .orElseThrow(() -> new UserNotFoundException(id));
    }

    // 수정 시 캐시 갱신
    @CachePut(value = "users", key = "#id")
    @Transactional
    public UserDto update(Long id, UpdateUserDto dto) {
        // ... 수정 로직
    }

    // 삭제 시 캐시 무효화
    @CacheEvict(value = "users", key = "#id")
    @Transactional
    public void delete(Long id) {
        userRepository.deleteById(id);
    }
}