Available as of Fuse Mediation Router 1.6

The freemarker: component allows you to process a message using a FreeMarker template. This can be ideal when using Templating to generate responses for requests.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-freemarker</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

freemarker:templateName[?options]

Where templateName is the classpath-local URI of the template to invoke; or the complete URL of the remote template (for example, file://folder/myfile.ftl).

You can append query options to the URI in the following format, ?option=value&option=value&...

Fuse Mediation Router will provide exchange information in the FreeMarker context (just a Map). The Exchange is transfered as:

The FreeMarker template resource is by default not hot reloadable for both file and classpath resources (expanded jar). If you set contentCache=false, then Fuse Mediation Router will not cache the resource and hot reloading is thus enabled. This scenario can be used in development.

Available as of Camel 2.1 Camel provides two headers by which you can define a different resource location for a template or the template content itself. If any of these headers is set then Camel uses this over the endpoint configured resource. This allows you to provide a dynamic template at runtime.

For example, you can define a route like the following:

from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl");

To use a FreeMarker template to formulate a response to InOut message exchanges (where there is a JMSReplyTo header).

If you want to process InOnly exchanges, you could use a FreeMarker template to transform the message before sending it on to another endpoint:

from("activemq:My.Queue").
  to(ExchangePattern.InOut,"freemarker:com/acme/MyResponse.ftl").
  to("activemq:Another.Queue");

And to disable the content cache (for example, for development usage where the .ftl template should be hot reloaded):

from("activemq:My.Queue").
  to(ExchangePattern.InOut,"freemarker:com/acme/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");

And for a file-based resource:

from("activemq:My.Queue").
  to(ExchangePattern.InOut,"freemarker:file://myfolder/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");

In Camel 2.1 it's possible to specify what template the component should use dynamically via a header, so for example:

from("direct:in").
  setHeader(FreemarkerConstants.FREEMARKER_RESOURCE_URI).constant("path/to/my/template.ftl").
  to("freemarker:dummy");

In this sample we want to use FreeMarker templating for an order confirmation email. The email template is laid out in FreeMarker as:

Dear ${headers.lastName}, ${headers.firstName}

Thanks for the order of ${headers.item}.

Regards Camel Riders Bookstore
${body}

And the java code:

private Exchange createLetter() {
    Exchange exchange = context.getEndpoint("direct:a").createExchange();
    Message msg = exchange.getIn();
    msg.setHeader("firstName", "Claus");
    msg.setHeader("lastName", "Ibsen");
    msg.setHeader("item", "Camel in Action");
    msg.setBody("PS: Next beer is on me, James");
    return exchange;
}

@Test
public void testFreemarkerLetter() throws Exception {
    MockEndpoint mock = getMockEndpoint("mock:result");
    mock.expectedMessageCount(1);
    mock.expectedBodiesReceived("Dear Ibsen, Claus\n\nThanks for the order of Camel in Action."
      + "\n\nRegards Camel Riders Bookstore\nPS: Next beer is on me, James");

    template.send("direct:a", createLetter());

    mock.assertIsSatisfied();
}

protected RouteBuilder createRouteBuilder() throws Exception {
    return new RouteBuilder() {
        public void configure() throws Exception {
            from("direct:a")
                .to("freemarker:org/apache/camel/component/freemarker/letter.ftl")
                .to("mock:result");
        }
    };
}