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= The <groovy> Ant Task

[[ThegroovyAntTask-groovyc]]
== `<groovy>`

[NOTE]
Here we describe an Ant task for using Groovy
from within an Ant build file.
You may also be interested in
Ant's built-in https://ant.apache.org/manual/Tasks/script.html[`script`] task
which supports Groovy and other languages, or
<<ant-builder.adoc#antbuilder,`AntBuilder`>> which lets you write Ant build scripts
in Groovy rather than XML.

Executes a series of Groovy statements from http://ant.apache.org/[Apache Ant].
Statements can either be read in from a resource or as direct text between the enclosing Groovy tags.

== Required taskdef

Assuming all the groovy jars you need are in _my.classpath_ (this will be `groovy-VERSION.jar`,
`groovy-ant-VERSION.jar` plus any modules and transitive dependencies you might be using)
you will need to declare this task at some point in the `build.xml` prior to
the `groovy` task being invoked.

[source,xml]
----
<taskdef name="groovy"
         classname="org.codehaus.groovy.ant.Groovy"
         classpathref="my.classpath"/>
----

You can simply place statements between the `groovy` tags like this:

[source,xml]
----
<groovy>
...
</groovy>
----

Or you can supply the Groovy source script as a resource. You can specify the pathname using the `src` attribute like this:

[source,xml]
----
<groovy src="/some/path/MyGroovyScript.groovy" otherAttributes="...">
----

Or as a nested `fileset` like this (though the fileset definition is expected to select just one file):

[source,xml]
----
<groovy>
    <fileset file="MyGroovyScript.groovy"/>
</groovy>
----

Or as a nested single element https://ant.apache.org/manual/Types/resources.html#collection[resource collection] which could look like any of these:

[source,xml]
----
<groovy>
    <file file="MyGroovyScript.groovy"/>
</groovy>

<groovy>
    <url url="https://some.domain/some/path/to/MyGroovyScript.groovy"/>
</groovy>

<groovy>
    <javaconstant name="some.packagename.SomeClass.MY_CODE_FRAGMENT"/>
</groovy>
----

You may also supply a https://ant.apache.org/manual/Types/filterchain.html[filter chain] like this:

[source,xml]
----
<groovy>
    <fileset file="MyGroovyScript.groovy"/>
    <!-- take 5 lines after skipping 18 lines, just as an example -->
    <filterchain>
        <headfilter lines="5" skip="18"/>
    </filterchain>
</groovy>
----


You might need to use the _contextClassLoader_ attribute (see below) if any of your modules load services via the classpath, e.g. `groovy-json`.

== <groovy> attributes

[cols="<1,<2,<1",options="header,footer"]
|============================================
|Attribute|Description|Required
|src|File containing Groovy statements. The directory containing the file is added to the classpath.| Yes, unless statements enclosed within tags
|classpath|The classpath to use.|No
|classpathref|The classpath to use, given as reference to a PATH defined elsewhere.|No
|output|Set the output file; defaults to the Ant log.|No
|append|If enabled and output is to a file, append to existing file rather than overwrite. Defaults to false.|No
|fork|If enabled the script will be executed in a forked JVM process (disabled by default).|No
|scriptBaseClass|The name of the base class for scripts.|No
|indy|If enabled the script will be executed with `invokedynamic` (disabled by default).|No
|parameters|Generates metadata for reflection on method parameter names on JDK 8 and above. Defaults to false. |No
|useGroovyShell|If enabled a new GroovyShell is used to run the script. Special variables won't be available but you don't need Ant in the classpath. Defaults to false. |No
|includeAntRuntime|If enabled the system classpath will be included on the classpath when forking. Defaults to true. |No
|stacktrace|If enabled a stacktrace will be reported if an error occurs during compilation. Defaults to false. |No
|configScript|Sets the configuration script for the groovy compiler configuration. |No
|contextClassLoader|If enabled, the contextClassLoader to be set with the classLoader of the shell used to run the script. Not used if fork is true. |No
|============================================

== Parameters specified as nested elements
=== <classpath>

Groovy's classpath attribute is a PATH like structure and can also be set via a nested classpath element.

=== <arg>

Arguments can be set via one or more nested <arg> elements using the standard Ant http://ant.apache.org/manual/using.html#arg[command line conventions].

== Available bindings

A number of bindings are in scope for use within your Groovy statements.

[cols="<1,<5",options="header,footer"]
|============================================
|Name|Description
|ant|an instance of `AntBuilder` that knows about the current ant project
|project|the current ant project
|properties|a `Map` of ant properties
|target|the owning target that invoked this groovy script
|task|the wrapping task, can access anything needed in `org.apache.tools.ant.Task`
|args|command line arguments, if any
|============================================

== Examples

Hello world, version 1:

[source,xml]
---------------------------------------------------------------------------------
<groovy>
println "Hello World"
</groovy>
---------------------------------------------------------------------------------

Hello world, version 2:

[source,xml]
---------------------------------------------------------------------------------
<groovy>
ant.echo "Hello World"
</groovy>
---------------------------------------------------------------------------------

List all xml files in the current directory:

[source,xml]
---------------------------------------------------------------------------------
<groovy>
xmlfiles = new File(".").listFiles().findAll{ it =~ "\.xml$" }
xmlfiles.sort().each { println it.toString() }
</groovy>
---------------------------------------------------------------------------------

List all xml files within a jar:

[source,xml]
---------------------------------------------------------------------------------
<zipfileset id="found" src="foobar.jar"
            includes="**/*.xml"/>
<groovy>
    project.references.found.each {
        println it.name
    }
</groovy>
---------------------------------------------------------------------------------

Run a script:

[source,xml]
---------------------------------------------------------------------------------
<groovy src="/some/directory/some/file.groovy">
  <classpath>
    <pathelement location="/my/groovy/classes/directory"/>
  </classpath>
</groovy>
---------------------------------------------------------------------------------

Find all `Builder` classes having an `org.*` package within a directory of jars:

[source,xml]
---------------------------------------------------------------------------------
<property name="local.target" value="C:/Projects/GroovyExamples"/>
<groovy>
import java.util.jar.JarFile
def classes = []
def resourceNamePattern = /org\/.*\/.*Builder.class/
def jarNamePattern = /.*(beta|commons).*jar$/
 
def libdir = new File("${properties['local.target']}/lib")
libdir.listFiles().grep(~jarNamePattern).each { candidate ->
    new JarFile(candidate).entries().each { entry ->
        if (entry.name ==~ resourceNamePattern) classes += entry.name
    }
}
properties["builder-classes"] = classes.join(' ')
</groovy>
<echo message='${builder-classes}'/>
---------------------------------------------------------------------------------

Which might result in something like:
[source]
---------------------------------------------------------------------------------
org/apache/commons/cli/PatternOptionBuilder.class org/apache/commons/cli/OptionBuilder.class org/codehaus/groovy/tools/groovydoc/GroovyRootDocBuilder.class org/custommonkey/xmlunit/HTMLDocumentBuilder.class org/custommonkey/xmlunit/TolerantSaxDocumentBuilder.class
---------------------------------------------------------------------------------

FileScanner version of above (with a slight variation on collecting the names):

[source,xml]
---------------------------------------------------------------------------------
<groovy>
import java.util.jar.JarFile
def resourceNamePattern = /org\/.*\/.*Builder.class/
def candidates = ant.fileScanner {
    fileset(dir: '${local.target}/lib') {
        include(name: '*beta*.jar')
        include(name: '*commons*.jar')
    }
}
def classes = candidates.collect {
    new JarFile(it).entries().collect { it.name }.findAll {
        it ==~ resourceNamePattern
    }
}.flatten()
properties["builder-classes"] = classes.join(' ')
</groovy>
---------------------------------------------------------------------------------

Calling out to a web service from your Ant script:

[source,xml]
---------------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<project name="SOAP example" default="main" basedir=".">
    <property environment="env"/>
    <property name="celsius" value="0"/>
    <target name="main">
        <taskdef name="groovy" classname="org.codehaus.groovy.ant.Groovy">
            <classpath>
                <fileset dir="${env.GROOVY_HOME}" includes="lib/groovy-*.jar,lib/ivy*.jar"/>
            </classpath>
        </taskdef>
        <groovy>
            @Grab('org.codehaus.groovy.modules:groovyws:0.5.1')
            import groovyx.net.ws.WSClient
            def url = 'http://www.w3schools.com/webservices/tempconvert.asmx?WSDL'
            def proxy = new WSClient(url, this.class.classLoader)
            proxy.initialize()
            ant.echo "I'm freezing at ${properties.celsius} degrees Celsius"
            properties.result = proxy.CelsiusToFahrenheit(properties.celsius)
        </groovy>
        <antcall target="results"/>
    </target>
    <target name="results">
        <echo message="I'm freezing at ${result} degrees Fahrenheit"/>
    </target>
</project>
---------------------------------------------------------------------------------

Which will output the following (along with some informational messages):

[source]
---------------------------------------------------------------------------------
main:
     ...
     [echo] I'm freezing at 0 degrees Celsius
results:
     [echo] I'm freezing at 32 degrees Fahrenheit

BUILD SUCCESSFUL
---------------------------------------------------------------------------------

Setting arguments:

[source,xml]
---------------------------------------------------------------------------------
<target name="run">
    <groovy>
        <arg line="1 2 3"/>
        <arg value="4 5"/>
        println args.size()
        println args[2]
        args.each{ ant.echo(message:it) }
    </groovy>
</target>
---------------------------------------------------------------------------------

Output:

[source]
---------------------------------------------------------------------------------
Buildfile: build.xml
 
run:
   [groovy] 4
   [groovy] 3
     [echo] 1
     [echo] 2
     [echo] 3
     [echo] 4 5
 
BUILD SUCCESSFUL
---------------------------------------------------------------------------------