public void exportStudentsToExcel() throws IOException {
final Spreadsheet spreadsheet = generateSpreadsheet();
getResponse().setContentType("application/vnd.ms-excel");
getResponse().setHeader("Content-disposition", "attachment; filename=" + getFilename() + ".xls");
spreadsheet.exportToXLSSheet(getResponse().getOutputStream());
getResponse().getOutputStream().flush();
getResponse().flushBuffer();
FacesContext.getCurrentInstance().responseComplete();
}