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Chapter 45. 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.

45.1. Dependencies
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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>
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45.2. URI Format
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The camel-groovy language component uses the following URI notation: 

groovy("someGroovyExpression")
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45.3. Groovy Options
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The Groovy language supports 2 options, which are listed below.

Expand
NameDefaultJava TypeDescription

resultType

 

String

Sets the class of the result type (type from output).

trim

true

Boolean

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

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

Java
from("queue:foo")
    .filter(groovy("request.lineItems.any { i -> i.value > 100 }"))
        .to("queue:bar")
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XML DSL
<route>
    <from uri="queue:foo"/>
    <filter>
        <groovy>request.lineItems.any { i -> i.value > 100 }</groovy>
        <to uri="queue:bar"/>
    </filter>
</route>
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45.5. Groovy Context
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Camel provides an exchange information in the Groovy context (just a Map). The Exchange is transferred as:

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keyvalue

exchange

The Exchange itself.

exchangeProperties

The Exchange properties.

variables

The variables

headers

The headers of the In message.

camelContext

The Camel Context.

request

The In message.

body

The In message body.

response

The Out message (only for InOut message exchange pattern).

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
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45.7. Customizing Groovy Shell
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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);
  }

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

45.8. Loading script from external resource
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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"`,
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For example, to refer to a file on the classpath you can use the following: 

.setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy")
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45.9. Spring Boot Auto-Configuration
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The component supports 2 options, which are listed below.

Expand
NameDescriptionDefaultType

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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