Groovy

Since Camel 1.3

Camel supports Groovy among other Scripting Languages to allow an Expression or Predicate to be used in the DSL or Xml Configuration.

To use a Groovy expression use the following Java code

... groovy("someGroovyExpression") ...

For example you could use the groovy function to create an Predicate in a Message Filter or as an Expression for a Recipient List

Groovy Options

The Groovy language supports 1 options, which are listed below.

Name Default Java Type Description

trim

true

Boolean

Whether to trim the value to remove leading and trailing whitespaces and line breaks

Customizing Groovy Shell

Sometimes you may need to use custom GroovyShell instance in your Groovy expressions. To provide custom GroovyShell, add implementation of the org.apache.camel.language.groovy.GroovyShellFactory SPI interface to your Camel registry. For example after adding the following bean to your Spring context…​

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 use your custom GroovyShell instance (containing your custom static imports), instead of the default one.

Customizing Groovy class file name

You may rarely in need of customizing generated Groovy class file name for debugging purposes. This is also possible by implementing getFileName method.

public class CustomGroovyShellFactory implements GroovyShellFactory {

  public GroovyShell createGroovyShell(Exchange exchange) {
    return new GroovyShell();
  }

  public String getFileName(Exchange exchange) {
    return "Foo.groovy";
  }

}

Example

// 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 the Spring DSL:

        <route>
            <from uri="queue:foo"/>
            <filter>
                <groovy>request.lineItems.any { i -> i.value > 100 }</groovy>
                <to uri="queue:bar"/>
            </filter>
        </route>

Additional arguments to ScriptingEngine

Since Camel 2.8

You can provide additional arguments to the ScriptingEngine using a header on the Camel message with the key CamelScriptArguments.
See this example:

Loading script from external resource

Since Camel 2.11

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")

How to get the result from multiple statements script

Since Camel 2.14

As the scripteengine 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 + 1

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.

Name Description Default Type

camel.language.groovy.enabled

Whether to enable auto configuration of the groovy language. This is enabled by default.

Boolean

camel.language.groovy.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks

true

Boolean
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