FileSystem is a namespace for FileObjects - a FileSystem has a root folder, which is a FileObject, which may have child files and folders - just like a file system on disk.

• 一个文件系统是文件对象的一个名域-一个文件系统拥有一个根文件夹，这个根文件夹就是一个文件对象，它可以拥有子文件或者子文件夹-就像磁盘上的文件系统一样。