Chapter 127. Groovy Language
Chapter 127. Groovy Language Available as of Camel version 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 127.1. 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 127.2. Spring Boot Auto-Configuration The component supports 2 options, which are listed below. Name Description Default Type camel.language.groovy.enabled Enable groovy language true Boolean camel.language.groovy.trim Whether to trim the value to remove leading and trailing whitespaces and line breaks true Boolean 127.3. 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. 127.4. Example // lets route if a line item is over USD100 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> 127.5. ScriptContext The JSR-223 scripting languages ScriptContext is pre configured with the following attributes all set at ENGINE_SCOPE : Attribute Type Value context org.apache.camel.CamelContext The Camel Context ( It cannot be used in groovy) camelContext org.apache.camel.CamelContext The Camel Context exchange org.apache.camel.Exchange The current Exchange request org.apache.camel.Message The message (IN message) response org.apache.camel.Message Deprecated : The OUT message. The OUT message if null by default. Use IN message instead. properties org.apache.camel.builder.script.PropertiesFunction Camel 2.9: Function with a resolve method to make it easier to use Camels Properties component from scripts. See further below for example. See Scripting Languages for the list of languages with explicit DSL support. 127.6. Additional arguments to ScriptingEngine Available as of 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: 127.7. Using properties function Available as of Camel 2.9 If you need to use the Properties component from a script to lookup property placeholders, then its a bit cumbersome to do so. For example to set a header name myHeader with a value from a property placeholder, which key is provided in a header named "foo". .setHeader("myHeader").groovy(""context.resolvePropertyPlaceholders( + '{{' + request.headers.get(&#39;foo&#39;) + '}}' + ")") From Camel 2.9 onwards you can now use the properties function and the same example is simpler: .setHeader("myHeader").groovy("properties.resolve(request.headers.get(&#39;foo&#39;))") 127.8. Loading script from external resource Available as of 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") 127.9. How to get the result from multiple statements script Available as of Camel 2.14 As the scripteengine evale method just return a Null if it runs a multiple statments 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 + 1 127.10. 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>
... groovy("someGroovyExpression") 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); } } // lets route if a line item is over USD100 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> .setHeader("myHeader").groovy(""context.resolvePropertyPlaceholders( + '{{' + request.headers.get(&#39;foo&#39;) + '}}' + ")") .setHeader("myHeader").groovy("properties.resolve(request.headers.get(&#39;foo&#39;))") .setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy") bar = "baz"; some other statements camel take the result value as the script evaluation result result = body * 2 + 1 <dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-groovy</artifactId> <version>x.x.x</version> </dependency>