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Date: Thu, 17 Sep 2009 07:38:44 -0700 (PDT)
From: "Lingjiao.Chen" <lingjiao.chen@cloudnovations.com>
To: user@poi.apache.org
Subject: Re: Converting an XSSF model to an HSSF model
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Hi Mark,

We are somewhat similar in situation. The second approach you purposed
sounds promising. Could you please forward the classes you've mentioned? 

Thanks.


MSB wrote:
> 
> Morning Greg,
> 
> Whilst I have had a very good look through the javadocs, I am by no means
> an expert so treat what I have to say with caution please. Having said
> that, I do not think there is an existing method within the POI API that
> you can use to transcode (convert) between an OpenXML file and a binary
> (BIFF8) file. You could use POI to create such a method however by
> stepping through the input workbook - an XSSFWorkbook in your case I would
> guess - and creating analogous objects within an HSSFWorkbook for
> everything you find there; if your workbooks are fairly simple then this
> could be the way to go but if they are more complex then that could
> involve some work.
> 
> You do have other options however and the best one - at least to my mind -
> would be OLE/COM. If you are working on a stand alone PC and have Office
> 2007 installed on that machine, then you can use OLE to control an
> instance of the Excel application and 'ask' it to convert the files for
> you. There are plenty of libraries you could use to accomplish this task
> but the only one I have any experience with is the ole32 package of the
> Standard Widget Toolkit. The SWT is part of the Eclispe IDE, can be
> downloaded separately and I have found it quite easy to work with. In
> fact, if you choose to go this way, let me know and I will forward a
> couple of classes that will allow you to use Excel to convert between
> different file types. You do need to be aware however that this approach
> does have problems; it is hard to trap and handle errors for example.
> Still, I think this is the beast approach as you are using the application
> created by the authors of the file formats involved.
> 
> A slightly modified version of this would be to use Excel macros to
> perform the conversions for you. It is possible to create a VBA macro that
> would open a file and save it in a different format. If you have lots of
> files to process, you could enter their names into the cells of a
> worksheet and have the macro iterate through the cells opening each file
> and then re-saving it in the appropriate format. Of course, this also
> depeneds upon your having access to Office 2007. I have never done this
> but it would be a simple task to use the macro recorder feature to
> prototype the code and then simply tweak it to do what you require.
> 
> The third option is OpenOffice. It uses filters to handle different file
> types and by specifying the filter the application should use, it is
> possible to convert between different file types. Again, it is possible to
> control OpenOffice from Java code through a clearly defined - though
> complex - interface. Using this technique again depened upon having
> OpenOffice and it's associated SDK installed. Furthermore, I would advise
> you to use either Eclipse or Netbeans as you IDE as both have a plugin
> that make developing UNO client applications far easier. As with OLE, I
> have code that I can let you have to accomplish this task. In my
> experience, OpenOffice is fine with all but the more complex spreadsheet
> files; for example, it has problems handling OpenXML spreadsheets that
> contain embedded objects and I am certain there will be other limitations.
> My only concern with this technique is that I have not yet been able to
> find the specific filter for opening and openXML based workbook even
> thgouhg I know that Calc can read such files.
> 
> Finally, there are on-line conversion services available. This would be,
> to my mind, a last resort as you would have to send your files across the
> internet to a third party; the security implications are obvious.
> 
> Hope this helps.
> 
> Yours
> 
> Mark B
> 
> 
> Greg Inns wrote:
>> 
>> Use Case: read in an XLSX file, convert it, and write out an XLS file.
>> 
>> It looks like both the HSSFWorkbook and the XSSFWorkbook both implement
>> the SS Workbook interface, but that's where it ends.  In my mind, it make
>> sense to be able to construct a HSSFWorkbook from an XSSFWorkbook and
>> visa versa, although I would expect there might be some lost information
>> in former case.  
>> 
>> Am I missing something in the API documentation?  Or something else?
>> 
>> 
>> 
> 
> 

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