Groovy
Since Camel 1.3
Camel has support for using Groovy.
For example, you can use Groovy in a Predicate with the Message Filter EIP.
groovy("someGroovyExpression")Examples
In the example below we use a groovy script as predicate in the message filter, to determine if any line items is over $100:
// lets route if a line item is over $100
from("queue:foo")
.filter(groovy("request.lineItems.any { i -> i.value > 100 }"))
.to("queue:bar")And in XML DSL:
<route>
<from uri="queue:foo"/>
<filter>
<groovy>request.lineItems.any { i -> i.value > 100 }</groovy>
<to uri="queue:bar"/>
</filter>
</route>How to get the result from multiple statements script
As the Groovy script engine evaluate method just return a Null if it runs a
multiple statements script. Camel now look up the value of script result
by using the key of "result" from the value set. If you have multiple
statements script, you need to make sure you set the value of result
variable as the script return value.
bar = "baz";
# some other statements ...
# camel take the result value as the script evaluation result
result = body * 2 + 1Customizing Groovy Shell
For very special use-cases you may need to use a custom GroovyShell instance in your
Groovy expressions. To provide the custom GroovyShell, add an implementation
of the org.apache.camel.language.groovy.GroovyShellFactory SPI
interface to the Camel registry.
public class CustomGroovyShellFactory implements GroovyShellFactory {
public GroovyShell createGroovyShell(Exchange exchange) {
ImportCustomizer importCustomizer = new ImportCustomizer();
importCustomizer.addStaticStars("com.example.Utils");
CompilerConfiguration configuration = new CompilerConfiguration();
configuration.addCompilationCustomizers(importCustomizer);
return new GroovyShell(configuration);
}
}Camel will then use your custom GroovyShell instance (containing your custom static imports), instead of the default one.
Loading script from external resource
You can externalize the script and have Camel load it from a resource
such as "classpath:", "file:", or "http:".
This is done using the following syntax: "resource:scheme:location",
eg to refer to a file on the classpath you can do:
.setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy")Dependencies
To use scripting languages in your camel routes you need to add a dependency on camel-groovy.
If you use Maven you could just add the following to your pom.xml,
substituting the version number for the latest and greatest release (see
the download page for the latest versions).
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-groovy</artifactId>
<version>x.x.x</version>
</dependency>Spring Boot Auto-Configuration
When using groovy with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-groovy-starter</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>The component supports 2 options, which are listed below.