shiro 访问鉴权：Realm
AuthorizingRealm->doGetAuthorizationInfo
doGetAuthorizationInfo
protected abstract AuthorizationInfo doGetAuthorizationInfo(PrincipalCollection principals)
Retrieves the AuthorizationInfo for the given principals from the underlying data store. When returning an instance from this method, you might want to consider using an instance of SimpleAuthorizationInfo, as it is suitable in most cases.
Parameters:
principals - the primary identifying principals of the AuthorizationInfo that should be retrieved.
Returns:
the AuthorizationInfo associated with this principals.
See Also:
SimpleAuthorizationInfo
shiro 需要访问数据库查询权限信息。
结合缓存框架，第一次查询权限信息后缓存，在缓存生存期内，访问鉴权使用缓存中的权限信息。
优点：减少数据库查询，缓存快速获取，提升了每次访问效率，减少了数据库压力。
缺点：涉及权限修改，生效会有一个最大缓存生存周期的间隔期。
解决方法：
每次修改权限后，调用 clearCachedAuthorizationInfo 刷新权限：
clearCachedAuthorizationInfo
protected void clearCachedAuthorizationInfo(PrincipalCollection principals)
Clears out the AuthorizationInfo cache entry for the specified account.
This method is provided as a convenience to subclasses so they can invalidate a cache entry when they change an account's authorization data (add/remove roles or permissions) during runtime. Because an account's AuthorizationInfo can be cached, there needs to be a way to invalidate the cache for only that account so that subsequent authorization operations don't used the (old) cached value if account data changes.
After this method is called, the next authorization check for that same account will result in a call to getAuthorizationInfo, and the resulting return value will be cached before being returned so it can be reused for later authorization checks.
If you wish to clear out all associated cached data (and not just authorization data), use the CachingRealm.clearCache(org.apache.shiro.subject.PrincipalCollection) method instead (which will in turn call this method by default).
Parameters:
principals - the principals of the account for which to clear the cached AuthorizationInfo.
示例项目：https://github.com/windwant/spring-dubbo-service
https://github.com/windwant/spring-boot-service