[Java] Class XmlTemplateEngine

Template engine for use in templating scenarios where both the template source and the expected output are intended to be XML.

Templates may use the normal '${expression}' and '$variable' notations to insert an arbitrary expression into the template. In addition, support is also provided for special tags: <gsp:scriptlet> (for inserting code fragments) and <gsp:expression> (for code fragments which produce output).

Comments and processing instructions will be removed as part of processing and special XML characters such as <, >, " and ' will be escaped using the respective XML notation. The output will also be indented using standard XML pretty printing.

The xmlns namespace definition for gsp: tags will be removed but other namespace definitions will be preserved (but may change to an equivalent position within the XML tree).

Normally, the template source will be in a file but here is a simple example providing the XML template as a string:

 def binding = [firstname:"Jochen", lastname:"Theodorou",
                nickname:"blackdrag", salutation:"Dear"]
 def engine = new groovy.text.XmlTemplateEngine()
 def text = '''\
 <?xml version="1.0" encoding="UTF-8"?>
 <document xmlns:gsp='http://groovy.codehaus.org/2005/gsp' xmlns:foo='baz' type='letter'>
   <gsp:scriptlet>def greeting = "${salutation}est"</gsp:scriptlet>
   <gsp:expression>greeting</gsp:expression>
   <foo:to>$firstname "$nickname" $lastname</foo:to>
   How are you today?
 </document>
 '''
 def template = engine.createTemplate(text).make(binding)
 println template.toString()
 

This example will produce this output:

 <document type='letter'>
 Dearest
 <foo:to xmlns:foo='baz'>
   Jochen &quot;blackdrag&quot; Theodorou
 </foo:to>
 How are you today?
 </document>
 

The XML template engine can also be used as the engine for TemplateServlet by placing the following in your web.xml file (plus a corresponding servlet-mapping element):

 <servlet>
   <servlet-name>XmlTemplate</servlet-name>
   <servlet-class>groovy.servlet.TemplateServlet</servlet-class>
   <init-param>
     <param-name>template.engine</param-name>
     <param-value>groovy.text.XmlTemplateEngine</param-value>
   </init-param>
 </servlet>