Hi Gary,
Ouh, I'm little kind of stuupid - I used Xalan 2.2.D7 and not D9..... D7 created this
NullPointerEx:
----
Registered class org.xmlsecurity.temp.FuncHere for here() function in internal table
FuncHere.execute() has been called
#NODESET
java.lang.NullPointerException
at org.apache.xml.dtm.ref.DTMNodeIterator.nextNode(DTMNodeIterator.java:198)
at org.xmlsecurity.temp.FuncHere.main(FuncHere.java:141)
Exception in thread "main"
----
Thanks for your help,
Christian
> This works fine for me. I had to put the class in a package because
> XalanJ assumes that anything registered without a package name is in its
> own functions package.
>
> My output is:
>
> C:\Temp>java foo.FuncHere
> Registered class foo.FuncHere for here() function in internal table
> FuncHere.execute() has been called
> #NODESET
> xpath
>
> Gary
>
> Christian Geuer-Pollmann wrote:
>>
>> /*
>> * Hi Xalan-Gurus,
>> * dear Gary,
>> *
>> * My extension function crashes (and i programmed some things that I
>> took * from the org.apache.xpath.functions package but did not
>> understood completely).
>> *
>> * Could you please have a short (or longer) look at the code and give me
>> some advise?
>> *
>> * Regards,
>> * Christian
>> *
>> * @author <mailto:[EMAIL PROTECTED]>
>> */
>>
>> import java.io.*;
>> import java.util.*;
>> import javax.xml.parsers.DocumentBuilder;
>> import javax.xml.parsers.DocumentBuilderFactory;
>> import org.apache.xalan.extensions.*;
>> import org.apache.xalan.templates.*;
>> import org.apache.xerces.dom.*;
>> import org.apache.xml.utils.*;
>> import org.apache.xml.dtm.*;
>> import org.apache.xpath.*;
>> import org.apache.xpath.objects.*;
>> import org.apache.xpath.functions.Function;
>> import org.apache.xpath.compiler.FunctionTable;
>> import org.apache.xpath.res.XPATHErrorResources;
>> import org.w3c.dom.*;
>> import org.w3c.dom.traversal.NodeIterator;
>>
>> /**
>> * The here function returns a node-set containing the attribute or
>> * processing instruction node or the parent element of the text node
>> * that directly bears the XPath expression. This expression results
>> * in an error if the containing XPath expression does not appear in the
>> * same XML document against which the XPath expression is being
>> evaluated. *
>> * Mainpart is stolen from FuncId.java
>> *
>> * @see
>> http://www.w3.org/Signature/Drafts/xmldsig-core/Overview.html#function-h
>> ere */
>> public class FuncHere extends Function {
>>
>> public XObject execute(XPathContext xctxt)
>> throws javax.xml.transform.TransformerException {
>>
>> System.out.println("FuncHere.execute() has been called");
>>
>> int currentNode = xctxt.getCurrentNode();
>> DTM dtm = xctxt.getDTM(currentNode);
>> int docContext = dtm.getDocument();
>>
>> if (DTM.NULL == docContext) {
>> error(xctxt, XPATHErrorResources.ER_CONTEXT_HAS_NO_OWNERDOC,
>> null); }
>>
>> XNodeSet nodes = new XNodeSet(xctxt.getDTMManager());
>> NodeSetDTM nodeSet = nodes.mutableNodeset();
>>
>> // Do processing here
>> {
>> int contextNode = xctxt.getContextNode();
>> int hereNode;
>> if (dtm.getNodeType(contextNode) == Node.ATTRIBUTE_NODE) {
>> hereNode = contextNode;
>> } else if (dtm.getNodeType(contextNode) ==
>> Node.PROCESSING_INSTRUCTION_NODE) {
>> hereNode = contextNode;
>> } else if (dtm.getNodeType(contextNode) == Node.TEXT_NODE) {
>> hereNode = dtm.getParent(contextNode);
>> } else {
>> hereNode = DTM.NULL;
>> }
>>
>> if (DTM.NULL != hereNode) {
>> nodeSet.addNode(hereNode);
>> }
>> }
>>
>> // must I do this detach() ?
>> nodeSet.detach();
>> return nodes;
>> }
>>
>> /**
>> * No arguments to process, so this does nothing.
>> * @param vars
>> * @param globalsSize
>> */
>> public void fixupVariables(java.util.Vector vars, int globalsSize) {}
>>
>> /**
>> * Method main
>> *
>> * @param unused
>> * @throws Exception
>> */
>> public static void main(String unused[]) throws Exception {
>>
>> String thisClass = FuncHere.class.getName();
>>
>> /**
>> * Try to register out here() implementation as internal function.
>> * @todo Is this too much hardcore?
>> */
>> FunctionTable.installFunction("here", new FuncHere());
>> System.out.println("Registered class " + thisClass
>> + " for here() function in internal table");
>>
>> //J-
>> String input =
>> "<?xml version='1.0' encoding='UTF-8' ?>\n"
>> + "<!DOCTYPE root [\n"
>> + "<!ATTLIST XPath\n"
>> + " Id ID #REQUIRED>\n"
>> + "]>\n"
>> + "<root>\n"
>> + " <XPath Id='hereInText'>here()</XPath>\n"
>> + " <XPath Id='hereInAttr' xpath='here()' />\n"
>> + "</root>";
>> //J+
>> DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
>>
>> dbf.setNamespaceAware(true);
>>
>> DocumentBuilder db = dbf.newDocumentBuilder();
>> Document doc = db.parse(new
>> ByteArrayInputStream(input.getBytes())); Node a =
>> XPathAPI.selectSingleNode(doc, "/root/XPath[2]"); Node attr =
>> ((Element) a).getAttributeNode("xpath");
>> XObject o = XPathAPI.eval(attr, attr.getNodeValue());
>>
>> System.out.println(o.getTypeString());
>>
>> if (o.getType() == XObject.CLASS_NODESET) {
>> NodeIterator ni = o.nodeset();
>> Node currNode;
>>
>> while ((currNode = ni.nextNode()) != null) {
>> System.out.println(currNode.getNodeName());
>> }
>> }
>> }
>> }
Mit freundlichen Gr��en,
Christian Geuer-Pollmann
--------------------------------------------------------------------------
Institute for Data Communications Systems University of Siegen
Hoelderlinstrasse 3 D-57068 Siegen Germany
mail: mailto:[EMAIL PROTECTED]
web: <http://www.nue.et-inf.uni-siegen.de/~geuer-pollmann/>
