From an XSLT stylesheet I would like to call a Java (extention) method.

The error message is:

The first argument to the non-static Java function 'doubleIntEcho' is not a valid object reference.

My simplified POC consists of 4 parts:

1. XML: file

<?xml version="1.0"?>
<value>
    <amount>1</amount>
    <amount>2</amount>
    <amount>3</amount>
</value>

2. XSLT stylesheet:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:jcall="java:x.y.z.XsltCallingJavaEchoTwice">
    <xsl:output method="xml"/>

    <xsl:template match="/value">
        <value>
            <xsl:apply-templates select="amount"/>
        </value>
    </xsl:template>

    <xsl:template match="amount">
        <xsl:copy>
            <value>
                <xsl:value-of select="text()"/>
            </value>
            <value-int>
                <xsl:value-of select="jcall:doubleIntEcho(number(.))"/>
            </value-int>
            <value-string>
                <xsl:value-of select="jcall:doubleStringEcho(text())"/>
            </value-string>
        </xsl:copy>
    </xsl:template>

</xsl:stylesheet>

3. Java class with the extention:

package x.y.z;

public class XsltCallingJavaEchoTwice {
    public static String doubleStringEcho( String input) {
        return "Source="   input   ", echo="   input   ", echo2="   input;
    }
    public static int doubleIntEcho( int input) {
        return input   input;
    }
}

4. The Java environment starting the XSLT transformation process:

public class XsltFilterParentWithAllChildren {

  private static final String XML_FILENAME = "files/xslt-call-java-amounts.xml";
  private static final String XSLT_FILENAME = "files/xslt-call-java-xsl.xsl";
  private static final String XML_OUTPUT_FILENAME = "files/output.xml";

  public static void main(String[] args) {
    deleteFile( XML_OUTPUT_FILENAME);
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try (InputStream is = new FileInputStream(XML_FILENAME)) {
      DocumentBuilder db = dbf.newDocumentBuilder();
      Document doc = db.parse(is);
      try (FileOutputStream output = new FileOutputStream(XML_OUTPUT_FILENAME)) {
        transform(doc, output);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }   
  private static void transform(Document doc, OutputStream output) throws TransformerException {
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer = transformerFactory.newTransformer(
            new StreamSource(new File(XSLT_FILENAME)));
    transformer.transform(new DOMSource(doc), new StreamResult(output));
  }   
  private static void deleteFile( String pathname) {
    new File( pathname).delete();
  }
}

CodePudding user response：

Looking at https://xalan.apache.org/xalan-j/extensions.html#ext-func-calls I would rather expect e.g. xmlns:java="http://xml.apache.org/xalan/java" and then e.g. <xsl:value-of select="java:x.y.z.XsltCallingJavaEchoTwice.doubleIntEcho(number(.))"/>.