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<!--
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(the "License"); you may not use this file except in compliance with
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<html>
<head>
<meta http-equiv="Content-Language" content="en-us"></meta>
<link rel="stylesheet" type="text/css" href="../stylesheets/style.css">
<title>Script Task</title>
</head>
<body>
<h2><a name="script">Script</a></h2>
<h3>Description</h3>
<p>Execute a script in a
<a href="http://jakarta.apache.org/bsf" target="_top">Apache BSF</a>
or
<a href="https://scripting.dev.java.net">JSR 223</a> supported language.
</p>
<p><b>Note:</b>
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 JDK6 and higher. This is controlled by the <code>manager</code>
attribute. The JSR 223 scripting manager is indicated by "javax".
</p>
<p>All items (tasks, targets, etc) of the running project are
accessible from the script, using either their <code>name</code> or
<code>id</code> attributes (as long as their names are considered
valid Java identifiers, that is).
This is controlled by the "setbeans" attribute of the task.
The name "project" is a pre-defined reference to the Project, which can be
used instead of the project name. The name "self" 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 target="_blank" href="http://www.mozilla.org/rhino/doc.html">
http://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 <i>JavaAdapter</i>. 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="http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&newwindow=1&frame=right&th=610d2db45c0756bd&seekm=391EEC3C.5236D929%40yahoo.com#link2">
Groups@Google: "Rhino, enum.js, JavaAdapter?"</a> by Norris Boyd in the newsgroup
<i>netscape.public.mozilla.jseng</i>.</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 border="1" cellpadding="2" cellspacing="0">
<tr>
<td valign="top"><b>Attribute</b></td>
<td valign="top"><b>Description</b></td>
<td align="center" valign="top"><b>Required</b></td>
</tr>
<tr>
<td valign="top">language</td>
<td valign="top">The programming language the script is written in.
Must be a supported Apache BSF or JSR 223 language</td>
<td valign="top" align="center">Yes</td>
</tr>
<tr>
<td valign="top">manager</td>
<td valign="top">
<em>Since: Ant 1.7. </em>
The script engine manager to use. This can have
one of three values ("auto", "bsf" or "javax").
The default value is "auto".
<dl>
<li>"bsf" use the BSF scripting manager to run
the language.</li>
<li>"javax" use the <em>javax.scripting</em> manager
to run the language. (This will only work for JDK6 and higher).</li>
<li>"auto" use the BSF engine if it exists,
otherwise use the <em>javax.scripting</em> manager.</li>
</dl>
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">src</td>
<td valign="top">The location of the script as a file, if not inline</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">setbeans</td>
<td valign="top">
This attribute controls whether to set variables for
all properties, references and targets in the running script.
If this attribute is false, only the the "project" and "self" variables are set.
If this attribute is true all the variables are set. The default value of this
attribute is "true". <em>Since Ant 1.7</em>
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">classpath</td>
<td valign="top">
The classpath to pass into the script. <em>Since Ant 1.7</em>
</td>
<td align="center" valign="top">No</td>
</tr>
<tr>
<td valign="top">classpathref</td>
<td valign="top">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 align="center" valign="top">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 <code>classpath</code> 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>
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 ${user.home}/.ant/lib free of lots of scripting language
specific jar files.
</p>
<p>
<b>NB: (Since Ant 1.7.1)</b>
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
javascript, jython, netrexx and jacl languages.
</p>
</p>
<h3>Examples</h3>
The following snippet shows use of five different languages:
<blockquote><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 ', $message, "\n"
</script>
<script language="jython">
print "message is %s" % message
</script>
</pre>
</blockquote>
<p>
Note that for the <i>jython</i> example, the script contents <b>must</b>
start on the first column.
</p>
<p>
Note also that for the <i>ruby</i> example, the names of the set variables are prefixed
by a '$'.
<p>
The following script shows a little more complicated jruby example:
</p>
<blockquote><pre>
<script language="ruby">
xmlfiles = Dir.new(".").entries.delete_if { |i| ! (i =~ /\.xml$/) }
xmlfiles.sort.each { |i| $self.log(i) }
</script>
</pre>
</blockquote>
<p>
The same example in groovy is:
</p>
<blockquote><pre>
<script language="groovy">
xmlfiles = new java.io.File(".").listFiles().findAll{ it =~ "\.xml$"}
xmlfiles.sort().each { self.log(it.toString())}
</script>
</pre>
</blockquote>
<p>
The following example shows the use of classpath to specify the location
of the beanshell jar file.
</p>
<blockquote><pre>
<script language="beanshell" setbeans="true">
<classpath>
<fileset dir="${user.home}/lang/beanshell" includes="*.jar" />
</classpath>
System.out.println("Hello world");
</script>
</pre>
</blockquote>
<p>
The following script uses javascript to create a number of
echo tasks and execute them.
</p>
<blockquote><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></blockquote>
<p>generates</p>
<blockquote><pre>
main:
1
4
9
16
25
36
49
64
81
100
BUILD SUCCESSFUL
</pre></blockquote>
<p>Now a more complex example using the Java API and the Ant API. The goal is to list the
filesizes of all files a <code><fileset/></code> caught.</p>
<blockquote><pre>
<?xml version="1.0" encoding="ISO-8859-1"?>
<project name="<font color=blue>MyProject</font>" 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
<font color=blue>// importPackage(java.io)</font>;
<font color=blue>importClass(java.io.File)</font>;
// Access to Ant-Properties by their names
dir = <font color=blue>project</font>.getProperty("fs.dir");
includes = <font color=blue>MyProject</font>.getProperty("fs.includes");
excludes = <font color=blue>self.getProject()</font> .<font color=blue>getProperty("fs.excludes")</font>;
// Create a <fileset dir="" includes=""/>
fs = project.<font color=blue>createDataType("fileset")</font>;
fs.setDir( new File(dir) );
<font color=blue>fs.setIncludes(includes)</font>;
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 = <font color=blue>new File(basedir, filename)</font>;
var size = file.length();
// create and use a Task via Ant API
echo = MyProject.<font color=blue>createTask("echo")</font>;
echo.setMessage(filename + ": " + size + " byte");
echo.<font color=blue>perform()</font>;
}
]]></script>
</target>
</project>
</pre></blockquote>
<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 <i>java</i> packages are available, so
<i>java.lang.System</i> can be directly imported with <code>importClass/importPackage</code>.
For other packages you have to prefix the full classified name with <i>Packages</i>.
For example Ant's <i>FileUtils</i> class can be imported with
<code>importClass(<b>Packages</b>.org.apache.tools.ant.util.FileUtils)</code>
<br>
The <code><script></code> task populates the Project instance under
the name <i>project</i>, so we can use that reference. Another way is to use its given name
or getting its reference from the task itself.<br>
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>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 execute() method, because the perform() method (implemented in Task itself) does the
appropriate logging before and after invoking execute().
</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>
<blockquote><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></blockquote>
<p>
An example of using this task to create a path
from a list of directories (using antcontrib's
<a href="http://ant-contrib.sourceforge.net/tasks/tasks/for.html">
<for></a> task) follows:
</p>
<blockquote><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></blockquote>
</body>
</html>
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