public class ExcelExporter extends Exporter {
@Override
public void export(FacesContext context, DataTable table, String filename, boolean pageOnly, int[] excludeColumns, String encodingType, MethodExpression preProcessor, MethodExpression postProcessor) throws IOException {
Workbook wb = new HSSFWorkbook();
Sheet sheet = wb.createSheet();
List<UIColumn> columns = getColumnsToExport(table, excludeColumns);
int numberOfColumns = columns.size();
String rowIndexVar = table.getRowIndexVar();
if(preProcessor != null) {
preProcessor.invoke(context.getELContext(), new Object[]{wb});