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See the License for the specific language governing permissions and limitations under the License. --> <html lang="en"> <head> <link rel="stylesheet" type="text/css" href="../stylesheets/style.css"> <title>Script Task</title> </head> <body> <h2 id="script">Script</h2> <h3>Description</h3> <p>Execute a script in a <a href="https://jakarta.apache.org/bsf" target="_top">Apache BSF</a> or <a href="https://jcp.org/aboutJava/communityprocess/maintenance/jsr223/223ChangeLog.html" target="_top">JSR 223</a> supported language. </p> <p><strong>Note</strong>: This task depends on external libraries not included in the Apache Ant distribution. See <a href="../install.html#librarydependencies">Library Dependencies</a> for more information.</p> <p>The task may use the BSF scripting manager or the JSR 223 manager that is included in JDK 6 and higher. This is controlled by the <var>manager</var> attribute. The JSR 223 scripting manager is indicated by <q>javax</q>.</p> <p>All items (tasks, targets, etc) of the running project are accessible from the script, using either their <var>name</var> or <var>id</var> attributes (as long as their names are considered valid Java identifiers, that is). This is controlled by the <var>setbeans</var> attribute of the task. The name <code class="code">project</code> is a pre-defined reference to the Project, which can be used instead of the project name. The name <code class="code">self</code> is a pre-defined reference to the actual <code><script></code>-Task instance.<br/>From these objects you have access to the Ant Java API, see the <a href="../api/index.html">JavaDoc</a> (especially for <a href="../api/org/apache/tools/ant/Project.html">Project</a> and <a href="../api/org/apache/tools/ant/taskdefs/optional/Script.html">Script</a>) for more information.</p> <p>If you are using JavaScript under BSF, a good resource is <a href="https://www.mozilla.org/rhino/doc.html" target="_top">https://www.mozilla.org/rhino/doc.html</a> as we are using their JavaScript interpreter.</p> <p>Scripts can do almost anything a task written in Java could do.</p> <p>Rhino provides a special construct—the <code>JavaAdapter</code>. With that you can create an object which implements several interfaces, extends classes and for which you can overwrite methods. Because this is an undocumented feature (yet), here is the link to an explanation: <a href="https://groups.google.com/forum/#!msg/netscape.public.mozilla.jseng/YlRQE0OvM8c/F8Mvq-XkpxcJ" target="_top">Google Groups: "Rhino, enum.js, JavaAdapter?"</a> by Norris Boyd in the newsgroup <em>netscape.public.mozilla.jseng</em>.</p> <p>If you are creating Targets programmatically, make sure you set the Location to a useful value. In particular all targets should have different location values.</p> <h3>Parameters</h3> <table class="attr"> <tr> <th scope="col">Attribute</th> <th scope="col">Description</th> <th scope="col">Required</th> </tr> <tr> <td>language</td> <td>The programming language the script is written in. Must be a supported Apache BSF or JSR 223 language</td> <td>Yes</td> </tr> <tr> <td>manager</td> <td> <em>Since Ant 1.7</em>. The script engine manager to use. This can have one of three values: <q>auto</q>, <q>bsf</q> or <q>javax</q>. <ul> <li><q>bsf</q> use the BSF scripting manager to run the language.</li> <li><q>javax</q> use the <code>javax.scripting</code> manager to run the language. (This will only work for JDK 6 and higher).</li> <li><q>auto</q> use the BSF engine if it exists, otherwise use the <code>javax.scripting</code> manager.</li> </ul> </td> <td>No; default is <q>auto</q></td> </tr> <tr> <td>src</td> <td>The location of the script as a file, if not inline</td> <td>No</td> </tr> <tr> <td>encoding</td> <td>The encoding of the script as a file. <em>Since Ant 1.10.2</em>.</td> <td>No; defaults to default JVM character encoding</td> </tr> <tr> <td>setbeans</td> <td>This attribute controls whether to set variables for all properties, references and targets in the running script. If this attribute is <q>false</q>, only the the <code>project</code> and <code>self</code> variables are set. If this attribute is <q>true</q> all the variables are set. <em>Since Ant 1.7</em></td> <td>No; defaults to <q>true</q></td> </tr> <tr> <td>classpath</td> <td>The classpath to pass into the script. <em>Since Ant 1.7</em></td> <td>No</td> </tr> <tr> <td>classpathref</td> <td>The classpath to use, given as a <a href="../using.html#references">reference</a> to a path defined elsewhere. <em>Since Ant 1.7</em></td> <td>No</td> </tr> </table> <h3>Parameters specified as nested elements</h3> <h4>classpath</h4> <p><em>Since Ant 1.7</em></p> <p><code>Script</code>'s <var>classpath</var> attribute is a <a href="../using.html#path">path-like structure</a> and can also be set via a nested <code><classpath></code> element. </p> <p>If a classpath is set, it will be used as the current thread context classloader, and as the classloader given to the BSF manager. This means that it can be used to specify the classpath containing the language implementation for BSF or for JSR 223 managers. This can be useful if one wants to keep <samp>${user.home}/.ant/lib</samp> free of lots of scripting language specific jar files.</p> <p><strong>Note</strong>: (<em>since Ant 1.7.1</em>) This classpath <em>can</em> be used to specify the location of the BSF jar file and/or languages that have engines in the BSF jar file. This includes the <q>javascript</q>, <q>jython</q>, <q>netrexx</q> and <q>jacl</q> languages.</p> <h3>Examples</h3> <p>The following snippet shows use of five different languages:</p> <pre> <property name="message" value="Hello world"/> <script language="groovy"> println("message is " + message) </script> <script language="beanshell"> System.out.println("message is " + message); </script> <script language="judoscript"> println 'message is ', message </script> <script language="ruby"> print 'message is ', $message, "\n" </script> <script language="jython"> print "message is %s" % message </script></pre> <p>Note that for the <q>jython</q> example, the script contents <strong>must</strong> start on the first column.</p> <p>Note also that for the <q>ruby</q> example, the names of the set variables are prefixed by a <q>$</q>.</p> <p>The following script shows a little more complicated JRuby example:</p> <pre> <script language="ruby"> xmlfiles = Dir.new(".").entries.delete_if { |i| ! (i =~ /\.xml$/) } xmlfiles.sort.each { |i| $self.log(i) } </script></pre> <p>The same example in Groovy is:</p> <pre> <script language="groovy"> xmlfiles = new java.io.File(".").listFiles().findAll{ it =~ "\.xml$"} xmlfiles.sort().each { self.log(it.toString()) } </script></pre> <p>The following example shows the use of classpath to specify the location of the beanshell jar file.</p> <pre> <script language="beanshell" setbeans="true"> <classpath> <fileset dir="${user.home}/lang/beanshell" includes="*.jar"/> </classpath> System.out.println("Hello world"); </script></pre> <p>The following script uses JavaScript to create a number of <code>echo</code> tasks and execute them.</p> <pre> <project name="squares" default="main" basedir="."> <target name="main"> <script language="javascript"> <![CDATA[ for (i = 1; i <= 10; i++) { echo = squares.createTask("echo"); echo.setMessage(i*i); echo.perform(); } ]]> </script> </target> </project></pre> <p>generates</p> <pre> main: 1 4 9 16 25 36 49 64 81 100 BUILD SUCCESSFUL</pre> <p>Now a more complex example using the Java API and the Ant API. The goal is to list the file sizes of all files a <code><fileset/></code> caught.</p> <pre> <?xml version="1.0" encoding="UTF-8"?> <project name="<span style="color:blue">MyProject</span>" basedir="." default="main"> <property name="fs.dir" value="src"/> <property name="fs.includes" value="**/*.txt"/> <property name="fs.excludes" value="**/*.tmp"/> <target name="main"> <script language="javascript"> <![CDATA[ // import statements <span style="color:blue">// importPackage(java.io)</span>; <span style="color:blue">importClass(java.io.File)</span>; // Nashorn syntax // <span style="color:blue">load("nashorn:mozilla_compat.js");</span> // or // <span style="color:blue">var File = Java.type('java.io.File');</span> // Access to Ant-Properties by their names dir = <span style="color:blue">project</span>.getProperty("fs.dir"); includes = <span style="color:blue">MyProject</span>.getProperty("fs.includes"); excludes = <span style="color:blue">self.getProject()</span>.<span style="color:blue">getProperty("fs.excludes")</span>; // Create a <fileset dir="" includes=""/> fs = project.<span style="color:blue">createDataType("fileset")</span>; fs.setDir(new File(dir)); <span style="color:blue">fs.setIncludes(includes)</span>; fs.setExcludes(excludes); // Get the files (array) of that fileset ds = fs.getDirectoryScanner(project); srcFiles = ds.getIncludedFiles(); // iterate over that array for (i = 0; i < srcFiles.length; i++) { // get the values via Java API var basedir = fs.getDir(project); var filename = srcFiles[i]; var file = <span style="color:blue">new File(basedir, filename)</span>; var size = file.length(); // create and use a Task via Ant API echo = MyProject.<span style="color:blue">createTask("echo")</span>; echo.setMessage(filename + ": " + size + " byte"); echo.<span style="color:blue">perform()</span>; } ]]></script> </target> </project></pre> <p>We want to use the Java API. Because we don't want always typing the package signature we do an import. Rhino knows two different methods for import statements: one for packages and one for a single class. By default only the <code>java</code> packages are available, so <code class="code">java.lang.System</code> can be directly imported with <code>importClass</code>/<code>importPackage</code>. For other packages you have to prefix the full classified name with <strong>Packages</strong>. For example Ant's <code class="code">FileUtils</code> class can be imported with <code class="code">importClass(<strong>Packages</strong>.org.apache.tools.ant.util.FileUtils)</code></p> <p>In Java 8 up until Java 14, you may use the built-in Nashorn JavaScript engine rather than Rhino (which is available in Java 7 runtime). Then, use <code>Java.type</code> as import statement for any Java class or <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/scripting/prog_guide/javascript.html#A1147207">the compatibility script</a>: <code>load("nashorn:mozilla_compat.js");</code>.</p> <p>Starting with Java 15 Nashorn has been removed again and you need to provide an external JavaScript engine. Your best option probably is <a href="https://github.com/graalvm/graaljs">GraalVM JavaScript</a> which requires you to add a lot of extra jars. For GraalVM JavaScript 20.1 you'll need <code>org.graalvm.js:js</code>, <code>org.graalvm.js:js-engine</code> which in turn require <code>org.graalvm.regex:regex</code>, <code>org.graalvm.truffle:truffle-api</code>, <code>org.graalvm.sdk:graal-sdk</code>, and <code>com.ibm.icu:icu4j</code>. GraalVM JavaScript is not a drop-in replacement for Nashorn, see Graal's <a href="https://github.com/graalvm/graaljs/blob/master/docs/user/NashornMigrationGuide.md">Nashorn Migration Guide</a> for more details.</p> <p>When using GraalVM JavaScript Ant will enable the feature <code>polyglot.js.allowAllAccess</code> in order to allow scripts to use Ant objects. By default it will also enable Nashorn compatibility mode, but you can disable this by setting the magic Ant property <code>ant.disable.graal.nashorn.compat</code> to <code>true</code>.</p> <p>The <code><script></code> task populates the Project instance under the name <code class="code">project</code>, so we can use that reference. Another way is to use its given name or getting its reference from the task itself. The Project provides methods for accessing and setting properties, creating DataTypes and Tasks and much more.<br/>After creating a FileSet object we initialize that by calling its set-methods. Then we can use that object like a normal Ant task (<code><copy></code> for example).<br/>For getting the size of a file we instantiate a <code class="code">java.io.File</code>. So we are using normal Java API here.<br/>Finally we use the <code><echo></code> task for producing the output. The task is not executed by its <code class="code">execute()</code> method, because the <code class="code">perform()</code> method (implemented in Task itself) does the appropriate logging before and after invoking <code class="code">execute()</code>.</p> <p>Here is an example of using beanshell to create an Ant task. This task will add filesets and paths to a referenced path. If the path does not exist, it will be created.</p> <pre> <!-- Define addtopath task --> <script language="beanshell"> import org.apache.tools.ant.Task; import org.apache.tools.ant.types.Path; import org.apache.tools.ant.types.FileSet; public class AddToPath extends Task { private Path path; public void setRefId(String id) { path = getProject().getReference(id); if (path == null) { path = new Path(getProject()); getProject().addReference(id, path); } } public void add(Path c) { path.add(c); } public void add(FileSet c) { path.add(c); } public void execute() { // Do nothing } } project.addTaskDefinition("addtopath", AddToPath.class); </script></pre> <p>An example of using this task to create a path from a list of directories (using Ant-Contrib's <a href="http://ant-contrib.sourceforge.net/tasks/tasks/for.html" target="_top"><for></a> task) follows:</p> <pre> <path id="main.path"> <fileset dir="build/classes"/> </path> <ac:for param="ref" list="commons,fw,lps" xmlns:ac="antlib:net.sf.antcontrib"> <sequential> <addtopath refid="main.path"> <fileset dir="${dist.dir}/@{ref}/main" includes="**/*.jar"/> </addtopath> </sequential> </ac:for></pre> </body> </html>