How to see who's logged in from server.xml file?

Question

I have configured the server.xml file in a Java Spring application to authenticate users when logging in from database tables and roles. I'm wondering how in Java code can I check who's logged in to the application?

I know that in a jsp file I can just use this following syntax to show the name:

${pageContext.request.userPrincipal.name} .

Answer 1

There is very beautiful article for this is given at http://www.baeldung.com/spring-security-track-logged-in-users

You can leverage the HttpSessionBindingListener to update the list of logged in users whenever user information is added to the session or removed from the session based on user logs into the system or logs out from the system.

It will listen to events of type HttpSessionBindingEvent, which are triggered whenever a value is set or removed, or, in other words, bound or unbound, to the HTTP session.

@Component
public class LoggedUser implements HttpSessionBindingListener {

    private String username; 
    private ActiveUserStore activeUserStore;

    public LoggedUser(String username, ActiveUserStore activeUserStore) {
        this.username = username;
        this.activeUserStore = activeUserStore;
    }

    public LoggedUser() {}

    @Override
    public void valueBound(HttpSessionBindingEvent event) {
        List<String> users = activeUserStore.getUsers();
        LoggedUser user = (LoggedUser) event.getValue();
        if (!users.contains(user.getUsername())) {
            users.add(user.getUsername());
        }
    }

    @Override
    public void valueUnbound(HttpSessionBindingEvent event) {
        List<String> users = activeUserStore.getUsers();
        LoggedUser user = (LoggedUser) event.getValue();
        if (users.contains(user.getUsername())) {
            users.remove(user.getUsername());
        }
    }

    // standard getter and setter
}

You can go through the whole code here

You can also retrieve the current logged in user from Spring security Go through this artical

Or through Request also

request.getUserPrincipal().getName();

Answer 2

In your Spring MVC Controller, just add the following statement:

String loggedUser = request.getUserPrincipal().getName();

where request is the object of HttpRequest type, made available to you by Spring on demand.

Answer 3

You can write a method to get current logged in user as you might need this various places like below :

public User getCurrentLoggedInUser() {
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        if (auth != null) {
            Object principal = auth.getPrincipal();
            if (principal instanceof User) {
                return ((User) principal);
            }
        }

    }