String Template
The string-template: component allows you to process a message using a String 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-stringtemplate</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
URI format
string-template:templateName[?options]
Where templateName is the classpath-local URI of the template to invoke; or the complete URL of the remote template.
You can append query options to the URI in the following format, ?option=value&option=value&...
Options
| Option |
Default |
Description |
| contentCache |
false |
Cache for the resource content when its loaded.
Note : as of Camel 2.9 cached resource content can be cleared via JMX using the endpoint's clearContentCache operation. |
| delimiterStart |
null |
Since Camel 2.11.1, configuring the variable start delimiter |
| delimiterStop |
null |
Since Camel 2.11.1, configuring the variable end delimiter |
Headers
Camel will store a reference to the resource in the message header with key, org.apache.camel.stringtemplate.resource. The Resource is an org.springframework.core.io.Resource object.
Hot reloading
The string template resource is by default hot-reloadable for both file and classpath resources (expanded jar). If you set contentCache=true, Camel loads the resource only once and hot-reloading is not possible. This scenario can be used in production when the resource never changes.
StringTemplate Attributes
Camel will provide exchange information as attributes (just a java.util.Map) to the string template. The Exchange is transfered as:
| key |
value |
| exchange |
The Exchange itself. |
| headers |
The headers of the In message. |
| camelContext |
The Camel Context. |
| request |
The In message. |
| in |
The In message. |
| body |
The In message body. |
| out |
The Out message (only for InOut message exchange pattern). |
| response |
The Out message (only for InOut message exchange pattern). |
Samples
For example you could use a string template as follows in order to formulate a response to a message:
from("activemq:My.Queue").
to("string-template:com/acme/MyResponse.tm");
The Email Sample
In this sample we want to use a string template to send an order confirmation email. The email template is laid out in StringTemplate as:
This example works for camel 2.11.0. If your camel version is less than 2.11.0, the variables should be started and ended with $.
Dear <headers.lastName>, <headers.firstName>
Thanks for the order of <headers.item>.
Regards Camel Riders Bookstore
<body>
And the java code is as follows:
See Also
