caching use-case

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-caching.html#boot-features-caching-provider-redis

Spring Boot auto-configures the cache infrastructure as long as caching support is enabled via the @EnableCaching annotation
@EnableCaching 指定spring boot 自动加载 cache组件。

如果不指定 缓存服务器， 则默认使用内存。