Spring Security - get User Name

If you want to retrieve the name of  a logged in user, do this:

import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;

private String getUserName() {

    Object principal = SecurityContextHolder
          .getContext()
          .getAuthentication()
          .getPrincipal();

    String userName;

    if (principal instanceof UserDetails) {
        userName = ((UserDetails)principal).getUsername();
    } else {
        userName = principal.toString();
    }
    return userName;
}