公用文件夹意味着文件可以公开访问.例如，任何人都可以通过进入
mysite.com/images/my-image.jpeg
However, files stored in storage directory are only available to your app.
Laravel has a php artisan storage:link command that adds a symlink to public from storage/app/public
这样做的原因是，您的storage可能不是本地文件系统，而是一个Amazon S3 bucket或Rackspace CDN(或其他任何东西)
You will need to setup your filesystem configurations by following the docs https://laravel.com/docs/5.6/filesystem
完成此操作后，您可以向/从存储位置获取/存储文件，而不是将所有文件都放在您的服务器上.
public和storage有两种显示文件的助手方法:
storage: storage_path('my-file.jpg')
public: asset('my-file.jpg')