@WebServlet("/controller")
public class MainServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private static final String ERROR_PAGE = "error.jsp";

    /**
     * @see HttpServlet#HttpServlet()
     */
    public MainServlet() {
        super();

    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        process(request, response);
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        process(request, response);
    }


    private void process(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {

        String commandName = request.getParameter("command");
        System.out.println("command: " + commandName);

        Command command = CommandContainer.get(commandName);

        String forward = ERROR_PAGE;
        try {
            forward = command.execute(request, response);
        } catch (Exception ex) {
            request.setAttribute("errorMessage", ex.getMessage());

        }
        // response.sendRedirect(forward);
         request.getRequestDispatcher(forward).forward(request, response);
    }

}

public class LoginCommand extends Command {

    private static final long serialVersionUID = -5337459310900087298L;
    private static final String SESSION_ATTR_LOGIN = "login";
    private static final String SESSION_ATTR_ID = "userId";
    private static final String SESSION_ATTR_ROLE = "userRole";
    private static final Logger LOG = Logger.getLogger(LoginCommand.class);
    private static final String PROFILE_JSP = "profile.jsp";
    private static final String USER_INFO_OBJECT="userInfo";
    private UsersService usersService;

    public LoginCommand(UsersService usersService) {
        this.usersService = usersService;
    }

    @Override
    public String execute(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        HttpSession session = request.getSession();
        String login = request.getParameter("login");
        String password = request.getParameter("password");
        if (login == null || password == null || login.isEmpty() || password.isEmpty()) {
            return null;
        }

        Users user = usersService.getUserByLogin(login);
        if (user == null || !password.equals(user.getPassword())) {
            return null;
        }

        Roles role = new Roles();
        role.setRoleType(RolesType.valueOf(this.usersService.getUserRole(login)));
        String forward = PROFILE_JSP;
            request.setAttribute("user", this.usersService.getUserByLogin(login));
        session.setAttribute(USER_INFO_OBJECT, user);
        session.setAttribute(SESSION_ATTR_LOGIN, login);
        session.setAttribute(SESSION_ATTR_ID, user.getIdUser());
        session.setAttribute(SESSION_ATTR_ROLE, role.getRoleType().toString());

        return forward;
    }

}