Why do not they upload the data from the BD with JSP?

I have this singleton class of connection to an Oracle Database 11g express edition database:

public class ConexionDB {

    private static ConexionDB _conexion;
    private Connection connection;

    /**
     * 
     */
    private ConexionDB() {
    }

    public static ConexionDB getInstancia() {
        if (_conexion == null) {
            try {
                Class.forName("oracle.jdbc.OracleDriver");
                String url = ("jdbc:oracle:thin:@localhost:1521:XE");
                Connection conn = (Connection) DriverManager.getConnection(url, "fukusuke","fukusuke");
                ConexionDB conexion = new ConexionDB();
                conexion.setConnection(conn);
                _conexion = conexion;
            } catch (Exception e) {
                throw new ConexionException("Ocurrio un error"
                        + " al conectar con la base de datos", e);
            }
        } 
        return _conexion;

    }

        /**
     * @return the connection
     */
    public Connection getConnection() {
        return connection;
    }

    /**
     * @param connection the connection to set
     */
    public void setConnection(Connection connection) {
        this.connection = connection;
    }
}

And I try to call the data with this Dao:

public List<Ingrediente> lista() throws SQLException, ClassNotFoundException {
        try{
            ConexionDB conn = ConexionDB.getInstancia();
            PreparedStatement consulta = conn.getConnection().prepareStatement("select * from ingrediente");
            ResultSet rst = consulta.executeQuery();
            List<Ingrediente> ingredientes = new ArrayList<Ingrediente>();
            while(rst.next()){
                ingredientes.add(parser(rst));
            }
            return ingredientes;
        }catch(Exception ex){
            System.out.println(ex.getMessage());
            return null;
        }
    }

    private Ingrediente parser(ResultSet rst) throws SQLException{
        Ingrediente ing = new Ingrediente();

        ing.setId_ingrediente(rst.getInt("id_ingrediente"));
        ing.setNombre(rst.getString("nombre"));
        ing.setFecha_elaboracion(rst.getTimestamp("fecha_elaboracion"));
        ing.setFecha_vencimiento(rst.getTimestamp("fecha_vencimiento"));
        ing.setFecha_registro(rst.getTimestamp("fecha_registro"));
        ing.setEstado(rst.getString("estado"));

        return ing;
    }

When I test the connection in a class Test everything is fine and it brings me the data, but when I try to show them in a JSP it gives me an error of connection to the database, some help ?. Thank you very much already.