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e967d77e02
PR: 5020 Reported By: jesse.glick@netbeans.com (Jesse Glick) git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271131 13f79535-47bb-0310-9956-ffa450edef68
123 lines
5.0 KiB
HTML
123 lines
5.0 KiB
HTML
<html>
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<head>
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<meta http-equiv="Content-Language" content="en-us">
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<title>Available Task</title>
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</head>
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<body>
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<h2><a name="available">Available</a></h2>
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<h3>Description</h3>
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<p>Sets a property if a resource is available at runtime. This resource can be a
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file, a directory, a class in the classpath, or a JVM system resource.</p>
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<p>If the resource is present, the property value is set to true by
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default; otherwise, the property is not set. You can set the value to
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something other than the default by specifying the <code>value</code> attribute.</p>
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<p>Normally, this task is used to set properties that are useful to avoid target
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execution depending on system parameters.</p>
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<h3>Parameters</h3>
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<table border="1" cellpadding="2" cellspacing="0">
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<tr>
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<td valign="top"><b>Attribute</b></td>
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<td valign="top"><b>Description</b></td>
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<td align="center" valign="top"><b>Required</b></td>
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</tr>
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<tr>
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<td valign="top">property</td>
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<td valign="top">The name of the property to set.</td>
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<td valign="top" align="center">Yes</td>
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</tr>
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<tr>
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<td valign="top">value</td>
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<td valign="top">The value to set the property to. Defaults to "true".</td>
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<td valign="top" align="center">No</td>
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</tr>
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<tr>
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<td valign="top">classname</td>
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<td valign="top">The class to look for in the classpath.</td>
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<td valign="middle" align="center" rowspan="3">Yes</td>
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</tr>
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<tr>
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<td valign="top">file</td>
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<td valign="top">The file to look for.</td>
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</tr>
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<tr>
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<td valign="top">resource</td>
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<td valign="top">The resource to look for in the JVM.</td>
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</tr>
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<tr>
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<td valign="top">classpath</td>
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<td valign="top">The classpath to use when looking up <code>classname</code> or <code>resource</code>.</td>
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<td align="center" valign="top">No</td>
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</tr>
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<tr>
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<td valign="top">filepath</td>
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<td valign="top">The path to use when looking up <code>file</code>.</td>
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<td align="center" valign="top">No</td>
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</tr>
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<tr>
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<td valign="top">classpathref</td>
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<td valign="top">The classpath to use, given as a <a href="../using.html#references">reference</a> to a path defined elsewhere.</td>
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<td align="center" valign="top">No</td>
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</tr>
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<tr>
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<td valign="top">type</td>
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<td valign="top">The type of <code>file</code> to look for, either a directory (<code>type="dir"</code>) or a file
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(<code>type="file"</code>). If not set, the property will be set if the name specified in the <code>file</code>
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attribute exists as either a file or a directory.</td>
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<td align="center" valign="top">No</td>
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</tr>
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</table>
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<h3>Parameters specified as nested elements</h3>
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<h4>classpath</h4>
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<p><code>Available</code>'s <code>classpath</code> attribute is a <a
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href="../using.html#path">path-like structure</a> and can also be set via a nested
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<code><classpath></code> element.</p>
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<h4>filepath</h4>
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<p><code>Available</code>'s <code>filepath</code> attribute is a <a
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href="../using.html#path">path-like structure</a> and can also be set via a nested
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<code><filepath></code> element.</p>
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<h3>Examples</h3>
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<pre> <available classname="org.whatever.Myclass" property="Myclass.present"/></pre>
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<p>sets the <code>Myclass.present</code> property to the value "true"
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if the class <code>org.whatever.Myclass</code> is found in Ant's classpath.</p>
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<pre>
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<property name="jaxp.jar" value="./lib/jaxp11/jaxp.jar"/>
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<available file="${jaxp.jar}" property="jaxp.jar.present"/>
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</pre>
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<p>sets the <code>jaxp.jar.present</code> property to the value "true"
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if the file <code>./lib/jaxp11/jaxp.jar</code> is found.</p>
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<pre>
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<available file="/usr/local/lib" type="dir" property="local.lib.present"/>
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</pre>
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<p>sets the <code>local.lib.present</code> property to the value "true"
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if the directory <code>/usr/local/lib</code> is found.</p>
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<pre>
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...in project ...
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<property name="jaxp.jar" value="./lib/jaxp11/jaxp.jar"/>
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<path id="jaxp" location="${jaxp.jar}"/>
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...in target ...
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<available classname="javax.xml.transform.Transformer" classpathref="jaxp" property="jaxp11.present"/>
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</pre>
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<p>sets the <code>jaxp11.present</code> property to the value "true"
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if the class <code>javax.xml.transform.Transformer</code> is found in the classpath referenced by <code>jaxp</code> (in this case, <code>./lib/jaxp11/jaxp.jar</code>).
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</p>
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<pre>
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<available property="have.extras" resource="extratasks.properties">
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<classpath>
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<pathelement location="/usr/local/ant/extra.jar/>
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</classpath>
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</available>
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</pre>
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<p>sets the <code>have.extras</code> property to the value "true"
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if the resource-file <code>extratasks.properties</code> is found.
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</p>
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<hr><p align="center">Copyright © 2001 Apache Software Foundation. All rights
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Reserved.</p>
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</body>
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</html>
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