Looks like a null check-in is desirable. If the intention is to add a
text node, which I assume was his intention, he wouldn't want a null
node. If the intention is to create an empty element, then he didn't
need the line that added the null text node.
As far as DOM goes, it would have been better if it was clearer on how
null be handled (a DOMException probably). But for a 10+ yr old API, the
case is not enough to call for a change of the behavior.
Thanks,
Joe
On 11/7/2016 8:09 AM, Langer, Christoph wrote:
Hi Xalan experts,
I’ve recently handled a customer issue about Text Nodes of value
‘null’ inside a DOM, causing an exception during XALAN XSLT
transformation. The repro case is quite simple. Consider the following
small Java sample [1] which creates a DOM from a very basic XML,
inserts a text node with value null into the DOM and then runs an
identity transformation on it. Without inserting the null Text node,
it would run without issues. However, the
com.sun.org.apache.xml.internal.serializer.ToUnknownStream class
stumbles over the null value and the transformation throws an NPE [2].
I believe this could be easily fixed by adding a null check in the
serializer and handling null like “”. However, would you agree that it
is a real issue worth fixing or should one rather stress the point
that Text Nodes of null are illegal? (Is that true, anyway? Didn’t
find any specification about that…) Please let me know your opinion –
and if you agree I would work on a fix.
Thanks in advance for comments
Christoph
[1] Sample code:
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
public class TestTransformWithNullText {
public static void main(String[] args) throws
ParserConfigurationException, SAXException, IOException,
TransformerException {
// create a small DOM
DocumentBuilder db =
DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = db.parse(new ByteArrayInputStream("<?xml
version=\"1.0\"?><DOCROOT/>".getBytes()));
// insert a bad element
Element e = doc.createElement("ERROR");
e.appendChild(doc.createTextNode(null));
doc.getDocumentElement().appendChild(e);
// transform
ByteArrayOutputStream bos = new ByteArrayOutputStream();
TransformerFactory.newInstance().newTransformer().transform(
new DOMSource(doc.getDocumentElement()), new StreamResult(bos));
System.out.println(bos);
}
}
[2] Exception encountered:
Exception in thread "main" javax.xml.transform.TransformerException:
java.lang.NullPointerException
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform([email protected]/TransformerImpl.java:789)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform([email protected]/TransformerImpl.java:376)
at
com.sap.cl.xml.test.transform.TestTransformWithNullText.main(TestTransformWithNullText.java:33)
Caused by: java.lang.NullPointerException
at
com.sun.org.apache.xml.internal.serializer.ToUnknownStream.characters([email protected]/ToUnknownStream.java:342)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:244)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:230)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:230)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:94)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity([email protected]/TransformerImpl.java:718)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform([email protected]/TransformerImpl.java:780)
... 2 more
---------
java.lang.NullPointerException
at
com.sun.org.apache.xml.internal.serializer.ToUnknownStream.characters([email protected]/ToUnknownStream.java:342)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:244)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:230)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:230)
at
com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse([email protected]/DOM2TO.java:94)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity([email protected]/TransformerImpl.java:718)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform([email protected]/TransformerImpl.java:780)
at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform([email protected]/TransformerImpl.java:376)
at
com.sap.cl.xml.test.transform.TestTransformWithNullText.main(TestTransformWithNullText.java:33)
