Package groovy.text

Class XmlTemplateEngine

java.lang.Object
groovy.text.TemplateEngine
groovy.text.XmlTemplateEngine
public class XmlTemplateEngine extends TemplateEngine
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 groovy.servlet.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>

  • Field Details

    • DEFAULT_INDENTATION

      public static final String DEFAULT_INDENTATION
      Default indentation sequence used for pretty-printed XML output.
      See Also:

  • Constructor Details

    • XmlTemplateEngine

      public XmlTemplateEngine() throws SAXException, ParserConfigurationException
      Creates an XML template engine using the default indentation and with XML validation disabled.
      Throws:
      SAXException - if the underlying parser cannot be configured
      ParserConfigurationException - if the XML parser cannot be created

    • XmlTemplateEngine

      public XmlTemplateEngine(String indentation, boolean validating) throws SAXException, ParserConfigurationException
      Creates an XML template engine with custom indentation and validation settings.
      Parameters:
      indentation - indentation string used when rendering nested XML nodes
      validating - true to enable XML validation while parsing templates
      Throws:
      SAXException - if the underlying parser cannot be configured
      ParserConfigurationException - if the XML parser cannot be created

    • XmlTemplateEngine

      public XmlTemplateEngine(XmlParser xmlParser, ClassLoader parentLoader)
      Creates an XML template engine backed by the supplied parser and a GroovyShell built from the parent loader.
      Parameters:
      xmlParser - parser used to read template XML
      parentLoader - class loader used to compile generated template scripts

    • XmlTemplateEngine

      public XmlTemplateEngine(XmlParser xmlParser, GroovyShell groovyShell)
      Creates an XML template engine backed by the supplied parser and shell.
      Parameters:
      xmlParser - parser used to read template XML
      groovyShell - shell used to compile generated template scripts

  • Method Details

    • setConfigurePrinter

      public void setConfigurePrinter(Closure configurePrinter)
      Closure that can be used to configure the printer. The printer is passed as a parameter to the closure. 
       new XmlTemplateEngine(configurePrinter: { it.preserveWhitespace = true })

    • createTemplate

      public Template createTemplate(Reader reader) throws CompilationFailedException, ClassNotFoundException, IOException
      Parses XML template source from the supplied reader and compiles it into a template.
      Specified by:
      createTemplate in class TemplateEngine
      Parameters:
      reader - XML template source
      Returns:
      a compiled XML template
      Throws:
      CompilationFailedException - if Groovy fails to compile the generated template script
      ClassNotFoundException - if the generated template class cannot be instantiated
      IOException - if reading the XML template fails

    • getIndentation

      public String getIndentation()
      Returns the indentation string used for pretty-printed XML output.
      Returns:
      the indentation sequence, never null

    • setIndentation

      public void setIndentation(String indentation)
      Sets the indentation string used for pretty-printed XML output.
      Parameters:
      indentation - indentation sequence to use; null restores DEFAULT_INDENTATION

    • toString

      public String toString()
      Returns a concise engine name for diagnostics.
      Overrides:
      toString in class Object
      Returns:
      the literal engine name