When using roles, how will the server understand that a user has logged in?

Question

Java

I want to write a site using roles (i.e. user admin manager) after climbing the Internet, I found out that the roles are registered in the users.xml file on the server, hence the
questions , but what to do with the user? How is the user logged in? I understand that the passwords from the user account should be in the database, but I can’t understand the roles.
Can you please explain to me or where can I read information about this?

Answer 1

I recommend to look at the library www.pac4j.org
Specifically by roles. There are several options, for example:
1) Authorize everyone indiscriminately, those authorized without a password get the user role
2) Authorize only managers and admins, unauthorized ones will automatically be - user
3) Authorize managers, admins, users with passwords and from social networks, unauthorized ones will automatically be unauthorized.