@Controller
public class StartController {
    @RequestMapping("/default")
    public String defaultAfterLogin(HttpServletRequest request) {
        if (request.isUserInRole("ADMIN")) {
            return "redirect:/admin/";
        }
        return "redirect:/user/";
    }
}

Principal: org.springframework.security.core.userdetails.User@79225df7:
Username: admin@test.de;
Password: [PROTECTED];
Enabled: true;
AccountNonExpired: true;
credentialsNonExpired: true;
AccountNonLocked: true;
Granted Authorities: ADMIN;
Credentials: [PROTECTED];
Authenticated: true;
Details: org.springframework.security.web.authentication.WebAuthenticationDetails@b364:
RemoteIpAddress: 0:0:0:0:0:0:0:1;
SessionId: null;
Granted Authorities: ADMIN