A commercial alternative to POI is produced by SoftArtisans
www.softartisans.com. Unlike POI which has reversed engineered the Excel
file format, SoftArtisans licensed the Word and Excel file formats from
Microsoft. Almost anything you can do in Excel you can do with SoftArtisans
OfficeWriter, including charts and pivot tables. It is pure Java.
I just finished working on a project to replace reports generated by a
normal report-generation tool with the SoftArtisans OfficeWriter
document-generator tool. It is for a mission critical and revenue critical
system at a fortune 100, NYSE listed company. Our end users generated
15,000+ Excel and Word documents in the final 10 days of our last fiscal
quarter. All of them created by SoftArtisan's Java OfficeWriter product and
only 1 SoftArtisan specific bug was discovered. It affected a very small
number of users. Softartisan's worked with us to isolate the issue and
provided a workaround for both our endusers and for our next production
release.
Their Java OfficeWriter product is still maturing so it did have some bugs
found in development we had to workaround and some of the API's can use
polishing. The support is truly excellent. They really, really worked hard
to help when we ran into development problems. It doesn't have report
generator type features like data grouping, but with work you can emulate
that and SoftArtisans is working very hard to add those features in the
future.
Big time thumbs up!