groovy.text

Class SimpleTemplateEngine

java.lang.Object

groovy.text.TemplateEngine

groovy.text.SimpleTemplateEngine

public class SimpleTemplateEngine
extends TemplateEngine

Processes template source files substituting variables and expressions into placeholders in a template source text to produce the desired output.

The template engine uses JSP style <% %> script and <%= %> expression syntax or GString style expressions. The variable 'out' is bound to the writer that the template is being written to.

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

 def binding = [
     firstname : "Grace",
     lastname  : "Hopper",
     accepted  : true,
     title     : 'Groovy for COBOL programmers'
 ]
 def engine = new groovy.text.SimpleTemplateEngine()
 def text = '''\
 Dear <%= firstname %> $lastname,

 We <% if (accepted) print 'are pleased' else print 'regret' %> \
 to inform you that your paper entitled
 '$title' was ${ accepted ? 'accepted' : 'rejected' }.

 The conference committee.
 '''
 def template = engine.createTemplate(text).make(binding)
 println template.toString()
 

This example uses a mix of the JSP style and GString style placeholders but you can typically use just one style if you wish. Running this example will produce this output:

 Dear Grace Hopper,

 We are pleased to inform you that your paper entitled
 'Groovy for COBOL programmers' was accepted.

 The conference committee.
 

The 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>SimpleTemplate</servlet-name>
   <servlet-class>groovy.servlet.TemplateServlet</servlet-class>
   <init-param>
     <param-name>template.engine</param-name>
     <param-value>groovy.text.SimpleTemplateEngine</param-value>
   </init-param>
 </servlet>
 

In this case, your template source file should be HTML with the appropriate embedded placeholders.

Constructor Summary

Constructors

Constructor and Description
SimpleTemplateEngine()
SimpleTemplateEngine(boolean verbose)
SimpleTemplateEngine(java.lang.ClassLoader parentLoader)
SimpleTemplateEngine(GroovyShell groovyShell)

Method Summary

Methods

Modifier and Type	Method and Description
Template	createTemplate(java.io.Reader reader)
boolean	isVerbose()
void	setVerbose(boolean verbose)

Methods inherited from class groovy.text.TemplateEngine

createTemplate, createTemplate, createTemplate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimpleTemplateEngine

public SimpleTemplateEngine()

SimpleTemplateEngine

public SimpleTemplateEngine(boolean verbose)

SimpleTemplateEngine

public SimpleTemplateEngine(java.lang.ClassLoader parentLoader)

SimpleTemplateEngine

public SimpleTemplateEngine(GroovyShell groovyShell)

Method Detail

createTemplate

public Template createTemplate(java.io.Reader reader)
                        throws CompilationFailedException,
                               java.io.IOException

Specified by:

createTemplate in class TemplateEngine

Throws:

CompilationFailedException

java.io.IOException

setVerbose

public void setVerbose(boolean verbose)

Parameters:

verbose - true if you want the engine to display the template source file for debugging purposes

isVerbose

public boolean isVerbose()