Excel file is becoming locked after transforming

[Alexander]

Hi All,

I am starting with JETT and face the following problem. Excel file becomes locked for chenging after the

transformer.transform(inFilename, outFilename, beans)

Should I call some closing method to unlock it for further use?

[Etienne Canaud]

Hi Alexander,

When I started using JETT, I found out that under windows, opening the XLSX file with POI by using the Workbook constructor that takes a File as an argument was keeping a handle on the file even after closing the workbook. I think the handle was only released upon garbage collection, but I wanted to be able to modify the file right after transformation.
I guess that the Transformer method of JETT you are using is also leveraging this POI constructor under the hood.

Since then, I'm using the transform method that takes a Workbook as input, and I make sure to create the Workbook by passing an InputStream that I can close myself after transform() has been called, ensuring that the file isn't locked. I had the same problem when manipulating files with POI only, so I guess the culprit here is POI, not JETT.

The strange point about that is that POI documentation clearly advises to use the File Workbook constructor for better performance ; unfortunately, that doesn't work for me and I'm still using the InputStream one in order to ensure the file doesn't get locked once I'm done with it. I may very well do something wrong, but so far this workaround has done wonders for me.

Cheers,
Etienne.