Excel export output file showing junk characters

I'm new to JasperReports. I'm able to export PDF report but excel (xls and xlsx) download file is showing junk characters. I didn't understand the issue. Excel export File content, generated by Java with JasperReports 6.11: screenshot of the exported excel file is attached Following code is used for export to Excel: contentType = "application/vnd.ms-excel"; exporter = new JRXlsExporter(); setExporterOutput(new SimpleOutputStreamExporterOutput(servletoutputstream)) .setExporterInput(new SimpleExporterInput(jasperPrint)); (exporter)).exportReport();