Annotation Based Expression Language

You can also use any of the Languages supported in Camel to bind expressions to method parameters when using Bean Integration. For example you can use any of these annotations:

Annotation

Description

@Bean

Inject a Bean expression

@BeanShell

Inject a BeanShell expression

@Constant

Inject a Constant expression

@EL

Inject an EL expression

@Groovy

Inject a Groovy expression

@Header

Inject a Header expression

@JavaScript

Inject a JavaScript expression

@MVEL

Inject a MVEL expression

@OGNL

Inject an OGNL expression

@PHP

Inject a PHP expression

@Python

Inject a Python expression

@Ruby

Inject a Ruby expression

@Simple

Inject an Simple expression

@XPath

Inject an XPath expression

@XQuery

Inject an XQuery expression

Example:

Advanced example using @Bean

And an example of using the the @Bean binding annotation, where you can use a POJO where you can do whatever java code you like:

And then we can have a spring bean with the id myCorrelationIdGenerator where we can compute the id.

The POJO MyIdGenerator has one public method that accepts two parameters. However we have also annotated this one with the @Header and @Body annotation to help Camel know what to bind here from the Message from the Exchange being processed.

Of course this could be simplified a lot if you for instance just have a simple id generator. But we wanted to demonstrate that you can use the Bean Binding annotations anywhere.

And finally we just need to remember to have our bean registered in the Spring Registry:

Example using Groovy

In this example we have an Exchange that has a User object stored in the in header. This User object has methods to get some user information. We want to use Groovy to inject an expression that extracts and concats the fullname of the user into the fullName parameter.

Groovy supports GStrings that is like a template where we can insert $ placeholders that will be evaluated by Groovy.

© 2004-2014 The Apache Software Foundation.
Apache Camel, Camel, Apache, the Apache feather logo, and the Apache Camel project logo are trademarks of The Apache Software Foundation. All other marks mentioned may be trademarks or registered trademarks of their respective owners.
Graphic Design By Hiram