5 1 12 XSL Extension

5.1.12 XSL Extension

For those situations where you would like to augment the functionality of XSLT with calls to a procedural language, Apache Xalan supports the creation and use of extension elements and extension functions.

Refer to xml.apache.org/xalan-j/extensions.html

Xalan-Java extensions

Compiled transformation style sheets (XSLTC) support the use of extension functions implemented in external Java classes.

The following example illustrates how to create and use an extension function.

<?xml version="1.0" encoding="UTF-8"?>
 
<Orders>
  <SalesOrder SONumber="">
    <Customer CustNumber="543">
      <CustName>ABC Industries</CustName>
      <Street>123 Main St</Street>
      <City>Chicago</City>
      <State>IL</State>
      <PostCode>60609</PostCode>
    </Customer>
  </SalesOrder>
</Orders>

Transformation style sheet:

<?xml version="1.0" encoding="UTF-8"?>
 
<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:rdml="http://www.lansa.com/2000/XML/Function"
    xmlns:xalan="http://xml.apache.org/xalan"
    xmlns:java="http://xml.apache.org/xalan/java"
    exclude-result-prefixes="xalan java">
 
<xsl:output method="xml" indent="yes" xalan:indent-amount="2"/>
 
<xsl:template match="/">
 
<rdml:function>
 
<rdml:fields>
    <xsl:call-template name="function-level"/>
</rdml:fields>
 
</rdml:function>
 
</xsl:template>
 
<xsl:template name="function-level">
 
<rdml:field name="DELIVERY" value="{java:com.acme.xsl.Extension.getValue(/Orders/SalesOrder/@Delivery,'MISSING')}"/>
 
<rdml:field name="ORDER" value="{java:com.acme.xsl.Extension.getValue(/Orders/SalesOrder/@SONumber,'MISSING','BLANK')}"/>
 
<rdml:field name="STATEDESC" value="{java:com.acme.xsl.Extension.getDescription(/Orders/SalesOrder/Customer/State)}"/>
 
<rdml:field name="CUSTNUM" value="{/Orders/SalesOrder/Customer/@CustNumber}"/>
<rdml:field name="NAME" value="{/Orders/SalesOrder/Customer/CustName}"/>
<rdml:field name="STREET" value="{/Orders/SalesOrder/Customer/Street}"/>
<rdml:field name="CITY" value="{/Orders/SalesOrder/Customer/City}"/>
<rdml:field name="STATE" value="{/Orders/SalesOrder/Customer/State}"/>
<rdml:field name="ZIP" value="{/Orders/SalesOrder/Customer/PostCode}"/>
 
</xsl:template>
 
</xsl:transform>

XML transformation:

<?xml version="1.0" encoding="UTF-8"?>
<rdml:function xmlns:rdml="http://www.lansa.com/2000/XML/Function">
  <rdml:fields>
    <rdml:field value="MISSING" name="DELIVERY"/>
    <rdml:field value="BLANK" name="ORDER"/>
    <rdml:field value="Illinois" name="STATEDESC"/>
    <rdml:field value="543" name="CUSTNUM"/>
    <rdml:field value="ABC Industries" name="NAME"/>
    <rdml:field value="123 Main St" name="STREET"/>
    <rdml:field value="Chicago" name="CITY"/>
    <rdml:field value="IL" name="STATE"/>
    <rdml:field value="60609" name="ZIP"/>
  </rdml:fields>
</rdml:function>

Java extension:

package com.acme.xsl ;
 
import org.w3c.dom.* ;
 
public class Extension
{
 
    public static String getDescription ( String code )
    {
        if ( code.equalsIgnoreCase ( "IL" ) )
        {
            return "Illinois" ;
        }
 
        return "?" ;
    }
 
    public static String getValue ( NodeList nodeList, String missingValue )
    {
        return getValue ( nodeList, missingValue, "" ) ;
    }
 
    public static String getValue ( NodeList nodeList, String missingValue, String blankValue )
    {
        int length = nodeList.getLength () ;
 
        if ( length == 0 )
        {
            return missingValue ;
        }
 
        Node node = nodeList.item ( 0 ) ;
 
        String nodeValue = node.getNodeValue () ;
 
        if ( nodeValue == null )
        {
            return blankValue ;
        }
 
        if ( nodeValue.trim().equals ( "" ) )
        {
            return blankValue ;
        }
 
        return nodeValue ;
    }
}