Authentication authentication = SecurityContextHolder.getContext().getAuthentication();

if (!(authentication instanceof AnonymousAuthenticationToken)) {
  String currentUserName = authentication.getName(); return currentUserName;
}

public class UserController extends Controller {

   protected static String COOKIE_NAME = "user";

   public static Result login() {
      //Считываем значения из формы:
      DynamicForm requestData = Form.form().bindFromRequest();
      String login = requestData.get("login");
      String password = requestData.get("password");

      if(userExists(login, password)){
         session(COOKIE_NAME, login);
         Logger.info("User found");
      }else{
         Logger.info("User not found");
      }

      return redirect(package.Application.index());
   }

   public static Result logout() {
      session().remove(COOKIE_NAME);
      return redirect(package.Application.index());
   }

   public static boolean isLoggedIn() {
      return session(COOKIE_NAME) != null;
   }

   public static String getSession() {
      return session(COOKIE_NAME);
   }
}

POST /login     package.UserController.login()
GET  /logout    package.UserController.logout()