exporter.setParameter(JRExporterParameter.JASPER_PRINT_LIST, jasperPrintList);
exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME, "build/reports/BatchExportReport.jxl.xls");
exporter.setParameter(JRXlsExporterParameter.IS_ONE_PAGE_PER_SHEET, Boolean.FALSE);
exporter.exportReport();
System.err.println("XLS creation time : " + (System.currentTimeMillis() - start));
}