官方文档这么说的（
https://userbase.kde.org/File_transfers ）
If your server requires authentication you will be prompted for your credentials in a popup dialog. Enter your username and password. If you wish to save them, check the relevant checkbox. Dolphin will store your passwords securely in your KDE Wallet. For faster access you can insert the username and password directly in the address bar using this format:
ftp://username:password@ftp.myserver.org; however we do not recommend this, as it is a security risk. Not only is it visible in your location bar, but it is stored in plain text, and so can be easily read by anyone with access to your home folder. Storing the password in KWallet is much safer, providing you have protected your KWallet with a password.