Java web mapping with xml

Question

Hello,

I am learning java for web, and I have a certain problem, I am not able to do the mapping in the xml file for the links of the pages to be cleaner.

I have the following class:

@WebServlet(urlPatterns = "/exec")
public class Controller extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        HttpSession session = req.getSession();
        session.removeAttribute("itemInvalido");
        String tarefa = req.getParameter("tarefa");
        if (tarefa == null) {
            throw new IllegalArgumentException("Voce esqueceu de passar a tarefa");
        }

            try {
                RequestDispatcher dispatcher;

                String nomeClasse = "br.com.portal.hidrosistemas.web." + tarefa;
                Class<?> type = Class.forName(nomeClasse);
                Tarefa instancia = (Tarefa) type.newInstance();
                String pagina = instancia.executa(req, resp);
                dispatcher = req.getRequestDispatcher(pagina);
                dispatcher.forward(req, resp);      

            }
            catch (Exception e) {
                e.printStackTrace();
            }
    }
}

And the Login class:

public class Login implements Tarefa {

    @Override
    public String executa(HttpServletRequest req, HttpServletResponse resp) throws Exception {

        HttpSession session = req.getSession();
        Empresa empresa = (Empresa) session.getAttribute("usuarioLogado");

        if(empresa != null)
            return "/WEB-INF/paginas/pedidos.jsp";


        try (Connection con = new ConnectionPool().getConnetion()) {
            String email = req.getParameter("e-mail");
            String senha = req.getParameter("senha");

            empresa = new EmpresaDAO(con).buscaLogin(email, senha);


            if (empresa != null) {
                session = req.getSession();
                session.setAttribute("usuarioLogado", empresa);
                session.setMaxInactiveInterval(10*60);
                return "/WEB-INF/paginas/pedidos.jsp";

            }
        }catch(NullPointerException e) {
            return "/index.jsp";
        }
        req.setAttribute("erroLogin", "Usuario ou senha invalidos");
        return "/index.jsp";
    }
}

xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">

  <display-name>hidro-sistemas</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

    <servlet>
    <servlet-name>login</servlet-name>
    <servlet-class>br.com.portal.hidrosistemas.web.Login</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>login</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>

</web-app>

But the links do not continue in the same way, for example after login: "http://localhost:8080/hidro-sistemas/exec? task=Login", I would like it to be /paginaInicial or /login.

What am I doing wrong?