The template framework in Groovy consists of a TemplateEngine abstract base class that engines must
implement and a Template interface that the resulting templates they generate must implement.
Included with Groovy is the SimpleTemplateEngine that allows you to use JSP-like scriptlets, script, and EL expressions in your template in order to generate parametrized text. Here is an example of using the system:
Though its possible to plug in any kind of template engine dialect, we can share the same API to invoke templates. e.g. we could create a Velocity / FreeMarker flavour TemplateEngine implemenation which could reuse GPath and auto-recompile to bytecode.
Article on templating with Groovy templates by Andrew Glover