I'm a bit confused with what is written in the documentation(s) for Freemarker and Restlet's freemarker extension.
Here's the situation: The restlet engine serves an HTML representation of a resource (e.g. www.mysite.com/{user}/updates). The resource returned for this URI is an HTML page containing all the updates, that is created with a freemarker template. This application is hosted on a Glassfish v3 server
Question(s):
The freemarker configuration should only be loaded once as per the freemarker documentation:
/* You should do this ONLY ONCE in the whole application life-cycle:Create and adjust the configuration */
Configuration cfg = new Configuration();
cfg.setDirectoryForTemplateLoading(
new File("/where/you/store/templates"));
cfg.setObjectWrapper(new DefaultObjectWrapper());
What is the best place to do this in a Java EE app? I am thinking of having it as context-param in web.xml and using a ServletContextListener - but I'm not sure how to go about doing that.
As per freemarker's documentation we could also add a freemarkerservlet and map .ftl url-patterns to it. But this is already mapped by a Restlet servlet (i.e., the url-pattern of "/"). So having another one for *.ftl doesn't make sense (or does it?)
So the question is basically about how best to integrate with the 'configuration' of Freemarker so that it happens only once and what is the 'entry-point' for that piece of code (who calls it). Has anyone successfully used Freemarker + restlet in a Java EE environment? Any ideas?
Thanks!
This was a tricky question - indeed. Required me to go through the implementation of the source files in org.restlet.ext.Freemarker package - Phew!
Here's how you can do it
If you need to create your OWN Configuration Object, set the 'templateLoader' to use and then have TemplateRepresentation 'work' on it for rendering:
Configuration cfg = new Configuration();
ContextTemplateLoader loader = new ContextTemplateLoader(getContext(),"war:///WEB-INF");
cfg.setTemplateLoader(loader);
TemplateRepresentation rep = null;
Mail mail = new Mail(); //The data object you wish to populate - example from Restlet itself
mail.setStatus("received");
mail.setSubject("Message to self");
mail.setContent("Doh!");
mail.setAccountRef(new Reference(getReference(), "..").getTargetRef()
.toString());
Map<String, Object> data = new HashMap<String, Object>();
data.put("status", mail.getStatus());
data.put("subject", mail.getSubject());
data.put("content", mail.getContent());
data.put("accountRef", mail.getAccountRef());
rep = new TemplateRepresentation("Mail.ftl", cfg, data, MediaType.TEXT_HTML);
return rep;
If you are happy with the default and wish to use a class loader based way of loading the templates
//Load the FreeMarker template
Representation mailFtl = new ClientResource(
LocalReference.createClapReference(getClass().getPackage())
+ "/Mail.ftl").get();
//Wraps the bean with a FreeMarker representation
return new TemplateRepresentation(mailFtl, mail, MediaType.TEXT_HTML);
If you want to initialize the Configuration Object once and set the template by calling the setServletContextForTemplateLoading(...) method on the configuration object. You could always do this in a ServletContextListener
public class Config implements ServletContextListener {
private static Configuration cfg = new Configuration();
@Override
public void contextInitialized(ServletContextEvent sce) {
ServletContext sc = sce.getServletContext();
cfg.setServletContextForTemplateLoading(sc, "/WEB-INF");
}
public static Configuration getFMConfig()
{
return cfg;
}
}
And then call the static getFMConfig() and pass it to TemplateRepresentation as in 1
Things to note:
Personal Frustration point - why isn't all this even clarified in the documentation or ANYWHERE :)
Hope it helps someone who stumbles upon this post! Phew!
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