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ant

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<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 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>&lt;script&gt;</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 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>


<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>&lt;classpath&gt;</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. This can be usefull if one wants
    to keep ${user.home}/.ant/lib free of lots of scripting language specific jar files.
  </p>
  <p>
    <b>NB:</b> This classpath cannot (currently) be used to specify the location of
    the BSF jar file.
  </p>
</p>
<h3>Examples</h3>
The following snippet shows use of five different languages:
  <blockquote><pre>
    &lt;property name="message" value="Hello world"/&gt;

    &lt;script language="groovy"&gt;
      println("message is " + message)
    &lt;/script&gt;

    &lt;script language="beanshell"&gt;
      System.out.println("message is " + message);
    &lt;/script&gt;

    &lt;script language="judoscript"&gt;
        println 'message is ', message
    &lt;/script&gt;

    &lt;script language="ruby"&gt;
        print 'message is ', $message, "\n"
    &lt;/script&gt;

    &lt;script language="jython"&gt;
print "message is %s" % message
    &lt;/script&gt;
</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 '$'.
  <p>
    The following script shows a little more complicated jruby example:
  </p>
  <blockquote><pre>
&lt;script language="ruby"&gt;
  xmlfiles = Dir.new(".").entries.delete_if { |i| ! (i =~ /\.xml$/) }
  xmlfiles.sort.each { |i| $self.log(i) }
&lt;/script&gt;
</pre>
  </blockquote>
  <p>
    The same example in groovy is:
  </p>
  <blockquote><pre>
&lt;script language="groovy"&gt;
  xmlfiles = new java.io.File(".").listFiles().findAll{ it =~ "\.xml$"}
  xmlfiles.sort().each { self.log(it.toString())}
&lt;/script&gt;
</pre>
  </blockquote>
  <p>
    The following example shows the use of classpath to specify the location
    of the beanshell jar file.
  </p>
  <blockquote><pre>
&lt;script language="beanshell" setbeans="true"&gt;
  &lt;classpath&gt;
    &lt;fileset dir="${user.home}/lang/beanshell" includes="*.jar" /&gt;
  &lt;/classpath&gt;
  System.out.println("Hello world");
&lt;/script&gt;
</pre>
  </blockquote>
  <p>
    The following script uses javascript to create a number of
    echo tasks and execute them.
  </p>
<blockquote><pre>
&lt;project name=&quot;squares&quot; default=&quot;main&quot; basedir=&quot;.&quot;&gt;

  &lt;target name=&quot;main&quot;&gt;

    &lt;script language=&quot;javascript&quot;&gt; &lt;![CDATA[

      for (i=1; i&lt;=10; i++) {
        echo = squares.createTask(&quot;echo&quot;);
        echo.setMessage(i*i);
        echo.perform();
      }

    ]]&gt; &lt;/script&gt;

  &lt;/target&gt;

&lt;/project&gt;
</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>&lt;fileset/&gt;</code> caught.</p>
<blockquote><pre>

&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
&lt;project name="<font color=blue>MyProject</font>" basedir="." default="main"&gt;

  &lt;property name="fs.dir" value="src"/&gt;
  &lt;property name="fs.includes" value="**/*.txt"/&gt;
  &lt;property name="fs.excludes" value="**/*.tmp"/&gt;

  &lt;target name="main"&gt;
    &lt;script language="javascript"&gt; &lt;![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 &lt;fileset dir="" includes=""/&gt;
      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&lt;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>;
      }
    ]]&gt;&lt;/script&gt;
  &lt;/target&gt;
&lt;/project&gt;
</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>&lt;script&gt;</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>&lt;copy&gt;</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>&lt;echo&gt;</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>
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