Basic question: How do I load an Excel template for use with POI and then save it to an XLS file?
Edit:
The answer is:
FileInputStream inputStream = new FileInputStream(new File(templateFile));
Workbook workbook = new HSSFWorkbook(inputStream);
(Just load the template as a workbook and then write the workbook as an XLS file elsewhere.)
Have you tried loading it up as a standard .xls using POI, amending it and then saving it ?
This is the approach I've used for inserting macros in a POI-generated .xls. I create the file with the macro (admittedly as an .xls) and then load it into my app, populate with data and save as a newly-created .xls. That all worked fine.