Chapter 17. Groovy

Groovy is a Java-based scripting language that allows quick parsing of object. The Groovy support is part of the camel-groovy module.

To use Groovy in your routes you need to add a dependencies on camel-groovy to your project as shown in Example 17.1, “Adding the camel-groovy dependency”.

<!-- Maven POM File -->
<properties>
  <camel-version>2.21.0.fuse-000077-redhat-1</camel-version>
  ...
</properties>

<dependencies>
  ...
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-groovy</artifactId>
    <version>${camel-version}</version>
  </dependency>
</dependencies>

To use the groovy() static method in your application code, include the following import statement in your Java source files:

import static org.apache.camel.builder.script.ScriptBuilder.*;

Table 17.1, “Groovy attributes” lists the built-in attributes that are accessible when using Groovy.

The attributes all set at ENGINE_SCOPE.

Example 17.2, “Routes using Groovy” shows two routes that use Groovy scripts.

<camelContext>
  <route>
    <from uri="direct:items" />
    <filter>
      <language language="groovy">request.lineItems.any { i -> i.value > 100 }</language>
      <to uri="mock:mock1" />
    </filter>
  </route>
  <route>
    <from uri="direct:in"/>
    <setHeader headerName="firstName">
      <language language="groovy">$user.firstName $user.lastName</language>
    </setHeader>
    <to uri="seda:users"/>
  </route>
</camelContext>

To access a property value from the properties component, invoke the resolve method on the built-in properties attribute, as follows:

.setHeader("myHeader").groovy("properties.resolve(PropKey)")

Where PropKey is the key of the property you want to resolve, where the key value is of String type.

For more details about the properties component, see Properties in the Apache Camel Component Reference Guide.

Sometimes, you might need to use the custom GroovyShell instance, in your Groovy expressions. To provide custom GroovyShell, add an implementation of the org.apache.camel.language.groovy.GroovyShellFactory SPI interface to your Camel registry.

For example, when you add the following bean to your Spring context, Apache Camel will use the custom GroovyShell instance that includes the custom static imports, instead of the default one.

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);
  }
 }