private Boolean lectorBD(String Nombre, String Pass){
        Boolean estado = false;

            try{
                String MySQLDriver ="com.mysql.jdbc.Driver",
                        DriGetConn = "jdbc:mysql://127.0.0.1/proyec",
                        //El nombre de usuario y la contraseña para entrar a BD
                        userBD = "root", passBD ="cu4tr04",
                        selectID ="SELECT id FROM usernames WHERE username ='",
                        IDpass ="", //El ID de la persona que se loguea
                        selectMD5 ="SELECT password FROM passwords WHERE id ='",
                        passMD5 = "", //La contraseña de la persona leida desde la BD
                        selectDatos ="SELECT nombre, apellido FROM dusuarios WHERE rut='";

                Class.forName(MySQLDriver);
                Connection conexion = DriverManager.getConnection
                        (DriGetConn, userBD, passBD);
                Statement query = conexion.createStatement(
                        ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
                ResultSet rs = query.executeQuery(selectID + Nombre +"'");
                rs.first();
                IDpass = rs.getString("id");
                rs.close();
                rs = query.executeQuery(selectMD5 + IDpass + "'");
                rs.first();
                passMD5 = rs.getString("password");
                rs.close();
                if(this.passMatch(passMD5, Pass)){
                    rs = query.executeQuery(selectDatos + IDpass +"'");
                    rs.first();
                    this.AttNombre = rs.getString(1);
                    this.AttAppe = rs.getString(2);
                    rs.close();
                    estado = true;
                }else {
                    this.Error = 3;
                }
                query.close(); conexion.close();
            }catch(SQLException ex){
               this.SQLEx = "Se produjo una excepción durante la conexión: "+ ex.toString();
               this.Error = 4;
            }catch(Exception ex){
                this.EX = "Se produjo una excepción: "+ ex.toString();
                this.Error = 5;
            }

        return estado;
    }

    private Boolean passMatch(String passMD5, String Pass){
        if(Pass.equals(passMD5)){
            return true;
        }else{
            return false;
        }
    }

    private Boolean validar(String parNom, String parPass){
        Boolean estado = false;
        if(!parNom.isEmpty()){
            if(!parPass.isEmpty()){
                estado = this.lectorBD(parNom,parPass);
            }else{ this.Error = 1; }
        }else{ this.Error = 2; }

        return estado;
    }

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        Boolean estado;
        String URL = "/ConectaBD/postLog.jsp";
        estado = this.validar(request.getParameter("nombre"), request.getParameter("hash"));
        HttpSession sesion = request.getSession(true);
        if(estado){
             sesion.setAttribute("nombre", this.AttNombre);
             sesion.setAttribute("ape", this.AttAppe);
        }else{
            URL = URL + "?error=" + this.Error;
        }

        response.sendRedirect(response.encodeURL(URL));
    }

}