Vaadin print report

*** on UI ***
Button print = new Button("Print");
print.addClickListener(new ClickListener() {
    @Override
    public void buttonClick(ClickEvent event) {
        AppUI.stampaReport("report.jasper", report.getId(), print);
    }
});
addComponent(print);

*** on helper class ***
public static void stampaReport(final String nomeFile, long p1, Button print) {
        String path = "/com/myapp/reports/";
        final String reportFile = path + nomeFile;
        final HashMap parameters = new HashMap();
        parameters.put("id", p1);

        try {
                StreamResource.StreamSource source = new StreamResource.StreamSource() {

                        public InputStream getStream() {
                                byte[] b = null;
                                Connection conn = null;
                                try {
                                        InputStream report = getClass().getClassLoader().getResourceAsStream(reportFile);
                                        if (report == null) {
                                                Notification.show("No report!", Type.ERROR_MESSAGE);
                                                return null;
                                        }
                                        conn = getDbHelp().getJDBCConnectionPool().reserveConnection();
                                        b = JasperRunManager.runReportToPdf(report, parameters, conn);
                                        conn.commit();
                                } catch (Exception e) {
                                        e.printStackTrace();
                                } finally {
                                        getDbHelp().getJDBCConnectionPool().releaseConnection(conn);
                                }

                                return new ByteArrayInputStream(b);
                        }
                };

                StreamResource resource = new StreamResource(source, "report.pdf");
                resource.getStream().setParameter("Content-Disposition", "attachment;filename=\"report.pdf\"");
                resource.setMIMEType("application/pdf");
                resource.setCacheTime(0);

                //Page.getCurrent().open(resource, "_blank", false);

                BrowserWindowOpener opener = new BrowserWindowOpener(resource);
                opener.extend(print);

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