XSLT Processing with Java : passing xml content in

Question

I would like to pass a parameter containing XML content when processing XSLT. Here is my code:

import javax.xml.transform.Result; 
import javax.xml.transform.Source; 
import javax.xml.transform.Transformer; 
import javax.xml.transform.TransformerException; 
import javax.xml.transform.TransformerFactory; 
import javax.xml.transform.stream.StreamResult; 
import javax.xml.transform.stream.StreamSource; 

File xmlFile = new File(xmlFilePath);
File xsltFile = new File(xslFilePath);
Source xmlSource = new StreamSource(xmlFile);
Result result = new StreamResult(System.out);

TransformerFactory transFact = TransformerFactory.newInstance();
Transformer trans = transFact.newTransformer(xsltSource);
trans.setParameter("foo", "<bar>Hello1</bar><bar>Hello2</bar>");
trans.transform(xmlSource, result);

Then I'd like to select the values contained in the 'bar' tag in my XSL file.

<xsl:param name="foo"/>
...
<xsl:value-of select="$foo//foo[1]" />

But this doesn't work, I get this error message:

org.apache.xpath.objects.XString cannot be cast to org.apache.xpath.objects.XNodeSet

So I guess I should pass an XML object to my setParameter method, but which one? I can't find a simple example how to create an XNodeSet object...

How can I do that? Thanks.

Answer 1

You might want to check the documentation of your XSLT processor what kind of parameter types it allows and whether and how it allows to pass in a node and not a string. If I understand http://www.saxonica.com/html/documentation/using-xsl/embedding/jaxp-transformation.html and http://www.saxonica.com/html/documentation/javadoc/net/sf/saxon/jaxp/TransformerImpl.html#setParameter(java.lang.String,%20java.lang.Object) correctly then Saxon allows you to pass in nodes in the form of its NodeInfo.

Answer 2

If you are using Saxon, the simplest solution is to pass a StreamSource as the parameter value:

setParameter("foo", new StreamSource(new StringReader("<bar>baz</bar>")));

But this might not work with other processors: JAXP leaves it implementation-defined what kinds of Object can be passed as parameter values.