Reading a transformation in from an InputStream (ie, lazy transformation)?

[Dave Herman <DH...@oppenheimerfunds.com>]

Hello,

A basic way to do a transformation seems to be to write it to an OutputStream, e.g.,

transformer.transform(new StreamSource(in), new StreamResult(out));

This forces me to do something like write to a ByteArrayOutputStream and then read those bytes back in. Is there a way to perform lazy transformation, that is, to read in a transformed document from an InputStream, thereby only performing the transformation piecmeal as I read in from the InputStream? I guess I could run the transformation in a separate thread and use piped streams, but that's not the same thing.

Thanks,
Dave Herman
dherman@oppenheimerfunds.com



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Re: Reading a transformation in from an InputStream (ie, lazytransformation)?

[Gary L Peskin <ga...@firstech.com>]

Dave Herman wrote:
> 
> Hello,
> 
> A basic way to do a transformation seems to be to write it to an OutputStream, e.g.,
> 
> transformer.transform(new StreamSource(in), new StreamResult(out));
> 
> This forces me to do something like write to a ByteArrayOutputStream and then read those bytes back in. Is there a way to perform lazy transformation, that is, to read in a transformed document from an InputStream, thereby only performing the transformation piecmeal as I read in from the InputStream? I guess I could run the transformation in a separate thread and use piped streams, but that's not the same thing.
> 
> Thanks,
> Dave Herman
> dherman@oppenheimerfunds.com

Dave --

AFAIK, the transformation is driven from the input source.  If you are
providing your input in the form of a stream, this will be the driver
for the transformation.  I think that you can accomplish what you want
by using a SAXResult that targets a SAX2 ContentHandler.  This
ContentHandler will be called by the transformation as it occurs.  Your
ContentHandler can accumulate the results or discard them or pass them
on or whatever you want.

For further info, see
http://xml.apache.org/xalan-j/usagepatterns.html#sax

Is this what you are looking for?

Gary