(Source code introduction
1. remote login (the user name and password are more than 3 characters long and successful. You can set your own password on the server)
2. including loading effects (multi-threaded processing, current event return data)
3. if the login is unsuccessful, you can prompt the error reason
4. save information after login (such as user name and password, which can be set by yourself)
5. have super complete and detailed comments (novice can understand))