Chapter 46. Groovy

When using camel-groovy with Red Hat build of Camel Spring Boot, add the following Maven dependency to your pom.xml to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-groovy-starter</artifactId>
</dependency>

The camel-groovy language component uses the following URI notation:

groovy("someGroovyExpression")

The Groovy language supports 2 options, which are listed below.

Following example uses a groovy script as predicate in the message filter, to determine if any line items are over $100:

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>

Camel provides an exchange information in the Groovy context (just a Map). The Exchange is transferred as:

As the Groovy script engine evaluate method returns a Null if it runs a multiple statements script. Camel looks up the value of script result by using the key of result from the value set. If you have multiple statements scripts, make sure to 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 + 1

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.

You can externalize the script and have Camel load it from a resource such as "classpath:", "file:", or "http:". You can achieve this by using the following syntax:

`"resource:scheme:location"`,

For example, to refer to a file on the classpath you can use the following:

.setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy")

The component supports 2 options, which are listed below.