File rutaFichero = fileChooser.getSelectedFile();
try {
descarga = new Descarga(tfUrl.getText(), rutaFichero.getAbsolutePath());
descarga.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent event) {
if (event.getPropertyName().equals("progress")) {
pbDescarga.setValue((Integer) event.getNewValue());
}