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")Usage
Groovy Context
Camel will provide exchange information in the Groovy context (just a Map). The Exchange is transferred as:
| key | value |
|---|---|
| The message body. |
| The headers of the message. |
| The headers of the message. |
| The exchange variables |
| The exchange variables |
| The exchange properties. |
| The exchange properties. |
| The |
| The Camel Context. |
| If the exchange failed then this is the caused exception. |
| The message. |
| Deprecated The Out message (only for InOut message exchange pattern). |
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 looks up the value of script result by using the key of result from the value set. If you have multiple statements scripts, 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", e.g., 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>Examples
In the example below, we use a groovy script as predicate in the message filter, to determine if any line items are over $100:
-
Java
-
XML DSL
from("queue:foo")
.filter(groovy("request.lineItems.any { i -> i.value > 100 }"))
.to("queue:bar")<route>
<from uri="queue:foo"/>
<filter>
<groovy>request.lineItems.any { i -> i.value > 100 }</groovy>
<to uri="queue:bar"/>
</filter>
</route>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.