Using stream to avoid temp file

Question

I'm trying to create a PDF document with Apache Library FOP. It works well but I have to create a temp file to store an intermediate file (test.fop).

Here is my function:

@RequestMapping(value = "/pdf")
public void showPdfReport(OutputStream pdfOutStream) throws Exception
{
    // Setup
    FopFactory fopFactory = FopFactory.newInstance();
    TransformerFactory factory = TransformerFactory.newInstance();

    // Transformation XML to XML-FO
    StreamSource xsltSource = new StreamSource(servletContext.getResourceAsStream("resources/xsl/pdfTemplate.fo"));
    Transformer transformer = factory.newTransformer(xsltSource);
    OutputStream fopOutStream = new BufferedOutputStream(new FileOutputStream(new File(
            "C:/Temp/tests/test.fop")));
    StreamSource xmlSource = new StreamSource(servletContext.getResourceAsStream("resources/xsl/test.xml"));
    StreamResult fopResult = new StreamResult(fopOutStream);
    transformer.transform(xmlSource, fopResult);

    //  Transformation XSL-FO to PDF
    Source fopSrc = new StreamSource(new File("C:/Temp/tests/test.fop"));
    Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, pdfOutStream);
    Result res = new SAXResult(fop.getDefaultHandler());
    transformer = factory.newTransformer();
    transformer.transform(fopSrc, res);
}

Is it possible to store test.fop in a stream or any buffer instead of a file?

Answer 1

There's an example on the FOP website that explains exactly this. The SAX events emitted from the XSLT transformation are directly fed into FOP. No buffering in a file or in memory.

Answer 2

Sure, you can pass any Reader or InputStream to the StreamSource constructor

You could use StringReader or ByteArrayInputStream for example.