How to write xslt extended method? Can you give an example?

Created May 7, 2012

Roseanne Zhang

What you want to do does not even require a customized java extention. Simply using java.util.Date is enough. However, if you want to format you date string properly, then you do need to write your own class.

I found some time, and wrote 2 examples. One does what you wanted to do. The other does more.

A simple Java extension example
You can apply it to any well-formed XML file. It is not a very good practice, since you must use transformer knowing Java. The better practice would be using Microsoft msxml. However, I need to learn it before giving an example.

The next FAQ allows you to change the date string format in your XSLT. <h5>XSLT sourece </h5>

<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:java="java">
  <!-- add a today-date to your XML under the root -->
  <xsl:template match="/*">
    <xsl:element name="{name(.)}">
      <today-date>
        <xsl:value-of select="java:util.Date.new()" />
      </today-date>
      <xsl:apply-templates />
    </xsl:element>
  </xsl:template>

  <!-- identity template -->
  <xsl:template match="@*|node()">
      <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
      </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

A customized Java extension example
You can apply it to any well-formed XML file. The date string format can be provided by <xsl:param> if desired. <h5>XSLT sourece </h5>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  xmlns:xobj="com.example.XObj" 
  version ="1.0">
  <!--<xsl:variable name="contextObj" select="xobj:new(.)" />-->
  <xsl:template match = "@*|node()">
    <xsl:copy>
      <xsl:apply-templates select = "@*|node()"/>
    </xsl:copy>
  </xsl:template>
  <xsl:template match="/*">
    <xsl:element name="{name(.)}" >
      <xsl:element name = "today-date">
        <xsl:value-of select="xobj:getDateString('EEE, MMM d, yyyy')" /> 
      </xsl:element>
      <xsl:apply-templates />
    </xsl:element>
  </xsl:template>
</xsl:stylesheet>

package com.example;
import java.util.Date;
import java.text.SimpleDateFormat;
public class XObj {
  public static String getDateString(String format) {
    SimpleDateFormat df = new SimpleDateFormat(format);
    return df.format(new Date());
  }
}

The code can also be found at XSLT Extension, advanced topics

Enjoy!!!