Saxon-HE Java 扩展功能（配置问题）

Question

I currently use Saxon9 open source version with extensions written in Java. I am trying to migrate to SaxonHE and I have read the documentation and examples shown here.

Java extension functions: full interface

and

Saxon Configuration File

When I try and execute my XSLT transformation I get errors like this when it encounters one of my external java functions.

  XPST0017: Cannot find a 2-argument function named
  Q{http://com.commander4j.Transformation.XSLT_Ext_NVL}nvl()

So here is what I've done so far.

My java extension function is written like this.

import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.lib.ExtensionFunctionCall;
import net.sf.saxon.lib.ExtensionFunctionDefinition;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.StringValue;

public class XSLT_Ext_NVL extends ExtensionFunctionDefinition
{

    @Override
    public SequenceType[] getArgumentTypes()
    {
        return new SequenceType[]{SequenceType.SINGLE_STRING, SequenceType.SINGLE_STRING};
    }

    @Override
    public StructuredQName getFunctionQName()
    {
        return new StructuredQName("c4j_XSLT_Ext_NVL", "http://com.commander4j.Transformation.XSLT_Ext_NVL", "nvl");
    }

    @Override
    public SequenceType getResultType(SequenceType[] arg0)
    {
         return SequenceType.SINGLE_STRING;
    }

    @Override
    public ExtensionFunctionCall makeCallExpression()
    {
           return new ExtensionFunctionCall() {
                @Override
                public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
                    String value = ((StringValue)arguments[0]).getStringValue();
                    String defaultValue = ((StringValue)arguments[1]).getStringValue();
                    
                    String result = "";

                    if (value == null)
                    {
                        value = "";
                    }

                    result = value;

                    if (result.equals(""))
                    {
                        result = defaultValue;
                    }

                    return StringValue.makeStringValue(result);
                }
            };
    }

}

I have created a Saxon configuration file which looks like this. My example looks a little different than the example on the Saxon website as that example includes the function name after the class name separated by a $ - when I tried it I got an error message that Saxon could not find the class.

    edition="HE"
    licenseFileLocation=""
    label="c4jMiddleware">

    <resources>
        <extensionFunction>com.commander4j.Transformation.XSLT_Ext_NVL</extensionFunction>
    </resources>
    
</configuration>

I am loading Configuration using this syntax.

Source xmlSource = new StreamSource(new File(System.getProperty("user.dir") + File.separator + "xml" + File.separator + "config" + File.separator +"SaxonConfiguration.xml"));
                                Configuration.readConfiguration(xmlSource);

Below is an extract from my XSLT which tries to invoke the java function.

<xsl:stylesheet 
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    xmlns:xs="http://www.w3.org/2001/XMLSchema" 
    xmlns:c4j="http://www.commander4j.com" 
    xmlns:c4j_XSLT_Ext_NVL="http://com.commander4j.Transformation.XSLT_Ext_NVL" 
    xmlns:c4j_XSLT_Ext="http://com.commander4j.Transformation.XSLTExtension"
    exclude-result-prefixes="xs c4j c4j_XSLT_Ext" version="2.0">

    <xsl:output encoding="UTF-8" indent="yes" method="xml"/>
    <xsl:strip-space elements="*"/>
    .
    .
    .
    <xsl:template match="xml">

        <xsl:param name="pack_conv" select="c4j_XSLT_Ext_NVL:nvl($pack_conv_temp, '1')"/>

If someone could give me a clue as to where I've gone wrong it would be most appreciated.

Dave

Answer 1

As Martin suggests, the most likely explanation is that you are not actually using the configuration you have created by reading the configuration file.