Sure. Start with an understanding that an XLS file encoded in an archive format much like Zip or Tar, etc. It contains a tree of files. A doc file (for instance) is in the exact SAME format. Our port of this is called POIFS.
One of the files in that archive is called "Workbook" and that is the *only* thing that HSSF currently deals with. When HSSF reads a workbook it reads in only the "Workbook" file from the XLS archive, and ignores all other entries. So when HSSF writes it back, it writes it back without the other files in the XLS archive. There are most likely other binary records in the "Workbook" file that point to the other files in the XLS archive (aka OLE 2 Compound Document), but HSSF should read them in and write them back out roughly where it found them. (not true for cellvalue records, which will probably be reordered slightly, but this has not been a problem up until now). To see the structure of the XLS file run org.apache.poi.poifs.dev.POIFSViewer (pass it the file). It should list the "directory tree". To see the structure of the "Workbook" file contained in the XLS archive you should use org.apache.poi.hssf.dev.BiffViewer (pass the file as the argument). If you have Cygwin (www.cygwin.com) or a Unix box then you should be able to output two files with a minor alteration and see the effect on the "Workbook" file by outputting the two and running "diff" against them. (You may be able to use a GUI diff, but the files can be quite large, so you probably only want to see the differences) So to add Macro capability you need to: 1. Make HSSF pay attention to the *macro* file in the XLS archive 2. Make it keep it 3. Make it rewrite it. 4. Start here http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFWorkbook_java.html#HSSFWorkbook and look at the public HSSFWorkbook <http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFWorkbook_java_ref.html#HSSFWorkbook.HSSFWorkbook%28POIFSFileSystem%29>(POIFSFileSystem <http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/poifs/filesystem/POIFSFileSystem_java.html#POIFSFileSystem> fs) method. Notice how it creates an InputStream from the "Workbook" file. From my understanding a Macro would be stored as another file in the OLE 2 Compound Document. You want that. So that should give you some understanding. As you can tell thats not too hard. So why haven't I done it? Well here are my additional requirments for this to make a production release (and it may be a pain but I think as a user you'll appreciate why). 1. I should be able to turn it off (conserve memory) if I want. Probably best to leave it on by default. 2. It will need appropriate unit tests. 3. It will need to be properly documented. (by supplying updates to the appropriate documentation) This information gives you a few options: 1. Wait for me to do this (might be awhile, low priority at the moment) 2. Do this and a. keep it to yourself b. supply it (as a patch) without the appropriate unit tests/docs and hope someone supplies them before POI 2.0 is released. (because if not I'll rip it out before release -- sorry) c. Supply a complete patch providing the feature, documentation and unit tests. (code complete) You'll get more credit, it will look nice on your resume, and I'll probably even mention you in the news blurb for the jakarta homepage. Hope this helps. BTW, if you're interested in adding addional features, in addition to the OpenOffice "XLS SPEC" linked from the home page, grab "Microsoft Excel 97 Developer's Kit" available used on Amazon for like $15 bucks. It explains the file format more fully than even I have. With the above information, tools, website docs and this book, you'd know everything I, Glen, Marc and Avik know about hacking HSSF. And thats all I have to say about that, -Andy Gump. Christian Bourque wrote: >Hi Andrew ! > >I'm working on a project where we use Excel files to exchange data with our >clients. So of course we are using POI/HSSF and we love it ! > >But we really need client side validation before the user submits is xls >template to our website. For that we think about using macros but I've read >on POI's mailing list archives that POI doesn't support macros yet ! > >You say it should be easy to implement ? > >I would love to contribute and do the modification myself but after >downloading the source code I realized that it was a little bit more >complicated than I tought. > >Would you have some directions to give me on how to do this tweak ? > >Thanks > >Regards > >Christian Bourque > > > > > -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
