Chapter 17. Using Ant from Gradle

In your build script, a property called ant is provided by Gradle. This is a reference to an AntBuilder instance. This AntBuilder is used to access Ant tasks, types and properties from your build script. There is a very simple mapping from Ant's build.xml format to Groovy, which is explained below.

You execute an Ant task by calling a method on the AntBuilder instance. You use the task name as the method name. For example, you execute the Ant echo task by calling the ant.echo() method. The attributes of the Ant task are passed as Map parameters to the method. Below is an example of the echo task. Notice that we can also mix Groovy code and the Ant task markup. This can be extremely powerful.

task hello << {
    String greeting = 'hello from Ant'
    ant.echo(message: greeting)
}

> gradle hello
:hello
[ant:echo] hello from Ant

BUILD SUCCESSFUL

Total time: 1 secs

You pass nested text to an Ant task by passing it as a parameter of the task method call. In this example, we pass the message for the echo task as nested text:

task hello << {
    ant.echo('hello from Ant')
}

> gradle hello
:hello
[ant:echo] hello from Ant

BUILD SUCCESSFUL

Total time: 1 secs

You pass nested elements to an Ant task inside a closure. Nested elements are defined in the same way as tasks, by calling a method with the same name as the element we want to define.

task zip << {
    ant.zip(destfile: 'archive.zip') {
        fileset(dir: 'src') {
            include(name: '**.xml')
            exclude(name: '**.java')
        }
    }
}

You can access Ant types in the same way that you access tasks, using the name of the type as the method name. The method call returns the Ant data type, which you can then use directly in your build script. In the following example, we create an Ant path object, then iterate over the contents of it.

task list << {
    def path = ant.path {
        fileset(dir: 'libs', includes: '*.jar')
    }
    path.list().each {
        println it
    }
}

More information about AntBuilder can be found in 'Groovy in Action' 8.4 or at the Groovy Wiki

task check << {
    ant.taskdef(resource: 'checkstyletask.properties') {
        classpath {
            fileset(dir: 'libs', includes: '*.jar')
        }
    }
    ant.checkstyle(config: 'checkstyle.xml') {
        fileset(dir: 'src')
    }
}

configurations {
    pmd
}

dependencies {
    pmd group: 'pmd', name: 'pmd', version: '4.2.5'
}

task check << {
    ant.taskdef(name: 'pmd',
                classname: 'net.sourceforge.pmd.ant.PMDTask',
                classpath: configurations.pmd.asPath)
    ant.pmd(shortFilenames: 'true',
            failonruleviolation: 'true',
            rulesetfiles: file('pmd-rules.xml').toURI().toString()) {
        formatter(type: 'text', toConsole: 'true')
        fileset(dir: 'src')
    }
}

You can use the ant.importBuild() method to import an Ant build into your Gradle project. When you import an Ant build, each Ant target is treated as a Gradle task. This means you can manipulate and execute the Ant targets in exactly the same way as Gradle tasks.

ant.importBuild 'build.xml'

<project>
    <target name="hello">
        <echo>Hello, from Ant</echo>
    </target>
</project>

> gradle hello
:hello
[ant:echo] Hello, from Ant

BUILD SUCCESSFUL

Total time: 1 secs

You can add a task which depends on an Ant target:

ant.importBuild 'build.xml'

task intro(dependsOn: hello) << {
    println 'Hello, from Gradle'
}

> gradle intro
:hello
[ant:echo] Hello, from Ant
:intro
Hello, from Gradle

BUILD SUCCESSFUL

Total time: 1 secs

Or, you can add behaviour to an Ant target:

ant.importBuild 'build.xml'

hello << {
    println 'Hello, from Gradle'
}

> gradle hello
:hello
[ant:echo] Hello, from Ant
Hello, from Gradle

BUILD SUCCESSFUL

Total time: 1 secs

It is also possible for an Ant target to depend on a Gradle task:

ant.importBuild 'build.xml'

task intro << {
    println 'Hello, from Gradle'
}

<project>
    <target name="hello" depends="intro">
        <echo>Hello, from Ant</echo>
    </target>
</project>

> gradle hello
:intro
Hello, from Gradle
:hello
[ant:echo] Hello, from Ant

BUILD SUCCESSFUL

Total time: 1 secs

There are several ways to set an Ant property, so that the property can be used by Ant tasks. You can set the property directly on the AntBuilder instance. The Ant properties are also available as a Map which you can change. You can also use the Ant property task. Below are some examples of how to do this.

ant.buildDir = buildDir
ant.properties.buildDir = buildDir
ant.properties['buildDir'] = buildDir
ant.property(name: 'buildDir', location: buildDir)

<echo>buildDir = ${buildDir}</echo>

Many Ant tasks set properties when they execute. There are several ways to get the value of these properties. You can get the property directly from the AntBuilder instance. The Ant properties are also available as a Map. Below are some examples.

<property name="antProp" value="a property defined in an Ant build"/>

println ant.antProp
println ant.properties.antProp
println ant.properties['antProp']

There are several ways to set an Ant reference:

ant.path(id: 'classpath', location: 'libs')
ant.references.classpath = ant.path(location: 'libs')
ant.references['classpath'] = ant.path(location: 'libs')

<path refid="classpath"/>

There are several ways to get an Ant reference:

<path id="antPath" location="libs"/>

println ant.references.antPath
println ant.references['antPath']

The Ant integration is provided by AntBuilder.