docs/manual/CoreTasks/property.html - ant - Git at Google

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 <head>
 <meta http-equiv="Content-Language" content="en-us">
 <title>Property Task</title>
 <link rel="stylesheet" type="text/css" href="../stylesheets/antmanual.css">
 </head>

 <body>

 <h2><a name="property">Property</a></h2>
 <h3>Description</h3>
 <p>Sets a property (by name and value), or set of properties (from file or
 resource) in the project.  Properties are case sensitive.</p>
  Properties are immutable: whoever sets a property first freezes it for the
  rest of the build; they are most definately not variable.
 <p>There are six ways to set properties:</p>
 <ul>
   <li>By supplying both the <i>name</i> and <i>value</i> attribute.</li>
   <li>By supplying both the <i>name</i> and <i>refid</i> attribute.</li>
   <li>By setting the <i>file</i> attribute with the filename of the property
     file to load. This property file has the format as defined by the file used
     in the class java.util.Properties, with the same rules about how
     non-ISO8859-1 characters must be escaped.</li>
   <li>By setting the <i>url</i> attribute with the url from which to load the
     properties. This url must be directed to a file that has the format as defined
     by the file used in the class java.util.Properties.</li>
   <li>By setting the <i>resource</i> attribute with the resource name of the
     property file to load. A resource is a property file on the current
     classpath, or on the specified classpath.</li>
   <li>By setting the <i>environment</i> attribute with a prefix to use.
     Properties will be defined for every environment variable by
     prefixing the supplied name and a period to the name of the variable.</li>
 </ul>
 <p>Although combinations of these ways are possible, only one should be used
 at a time. Problems might occur with the order in which properties are set, for
 instance.</p>
 <p>The value part of the properties being set, might contain references to other
 properties. These references are resolved at the time these properties are set.
 This also holds for properties loaded from a property file.</p>
 <p>A list of predefined properties can be found <a
 href="../using.html#built-in-props">here</a>.</p>

 <h4>OpenVMS Users</h4>
 <p>With the <code>environment</code> attribute this task will load all defined
 logicals on an OpenVMS system.  Logicals with multiple equivalence names get
 mapped to a property whose value is a comma separated list of all equivalence
 names.  If a logical is defined in multiple tables, only the most local
 definition is available (the table priority order being PROCESS, JOB, GROUP,
 SYSTEM).
 </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">name</td>
     <td valign="top">the name of the property to set.</td>
     <td valign="top" align="center">No</td>
   </tr>
   <tr>
     <td valign="top">value</td>
     <td valign="top">the value of the property.</td>
     <td valign="middle" align="center" rowspan="3">One of these, when using the
        name attribute</td>
   </tr>
   <tr>
     <td valign="top">location</td>
     <td valign="top">Sets the property to the absolute filename of the
       given file. If the value of this attribute is an absolute path, it
       is left unchanged (with / and \ characters converted to the
       current platforms conventions). Otherwise it is taken as a path
       relative to the project's basedir and expanded.</td>
   </tr>
   <tr>
     <td valign="top">refid</td>
     <td valign="top"><a href="../using.html#references">Reference</a> to an object
       defined elsewhere. Only yields reasonable results for references
       to <a href="../using.html#path">PATH like structures</a> or properties.</td>
   </tr>
   <tr>
     <td valign="top">resource</td>
     <td valign="top">the resource name of the property file.</td>
     <td valign="middle" align="center" rowspan="4">One of these, when
       <b>not</b> using the name attribute</td>
   </tr>
   <tr>
     <td valign="top">file</td>
     <td valign="top">the filename of the property file .</td>
   </tr>
   <tr>
     <td valign="top">url</td>
     <td valign="top">the url from which to read properties.</td>
   </tr>
   <tr>
     <td valign="top">environment</td>
     <td valign="top">the prefix to use when retrieving environment variables. Thus
     if you specify environment=&quot;myenv&quot; you will be able to access OS-specific
     environment variables via property names &quot;myenv.PATH&quot; or
     &quot;myenv.TERM&quot;. Note that if you supply a property name with a final
     &quot;.&quot; it will not be doubled. ie environment=&quot;myenv.&quot; will still
     allow access of environment variables through &quot;myenv.PATH&quot; and
     &quot;myenv.TERM&quot;. This functionality is currently only implemented
     on select platforms. Feel free to send patches to increase the number of platforms
     this functionality is supported on ;).<br>
     Note also that properties are case sensitive, even if the
     environment variables on your operating system are not, e.g. it
     will be ${env.Path} not ${env.PATH} on Windows 2000.</td>

   </tr>
   <tr>
     <td valign="top">classpath</td>
     <td valign="top">the classpath to use when looking up a resource.</td>
     <td align="center" valign="top">No</td>
   </tr>
   <tr>
     <td valign="top">classpathref</td>
     <td valign="top">the classpath to use when looking up a resource,
       given as <a href="../using.html#references">reference</a> to a &lt;path&gt; defined
       elsewhere..</td>
     <td align="center" valign="top">No</td>
   </tr>
   <tr>
     <td valign="top">prefix</td>
     <td valign="top">Prefix to apply to properties loaded using <code>file</code>
     or <code>resource</code>. A "." is appended to the prefix if not specified.</td>
     <td align="center" valign="top">No</td>
   </tr>
 </table>
 <h3>Parameters specified as nested elements</h3>
 <h4>classpath</h4>
 <p><code>Property</code>'s <i>classpath</i> attribute is a <a
 href="../using.html#path">PATH like structure</a> and can also be set via a nested
 <i>classpath</i> element.</p>
 <h3>Examples</h3>
 <pre>  &lt;property name=&quot;foo.dist&quot; value=&quot;dist&quot;/&gt;</pre>
 <p>sets the property <code>foo.dist</code> to the value &quot;dist&quot;.</p>
 <pre>  &lt;property file=&quot;foo.properties&quot;/&gt;</pre>
 <p>reads a set of properties from a file called &quot;foo.properties&quot;.</p>
 <pre>  &lt;property url=&quot;http://www.mysite.com/bla/props/foo.properties&quot;/&gt;</pre>
 <p>reads a set of properties from the address &quot;http://www.mysite.com/bla/props/foo.properties&quot;.</p>
 <pre>  &lt;property resource=&quot;foo.properties&quot;/&gt;</pre>
 <p>reads a set of properties from a resource called &quot;foo.properties&quot;.</p>
 <p>Note that you can reference a global properties file for all of your Ant
 builds using the following:</p>
 <pre>  &lt;property file=&quot;${user.home}/.ant-global.properties&quot;/&gt;</pre>
 <p>since the &quot;user.home&quot; property is defined by the Java virtual machine
 to be your home directory.  Where the &quot;user.home&quot; property resolves to in
 the file system depends on the operating system version and the JVM implementation.
 On Unix based systems, this will map to the user's home directory. On modern Windows
 variants, this will most likely resolve to the user's directory in the &quot;Documents
 and Settings&quot; folder. Older windows variants such as Windows 98/ME are less
 predictable, as are other operating system/JVM combinations.</p>

 <pre>
   &lt;property environment=&quot;env&quot;/&gt;
   &lt;echo message=&quot;Number of Processors = ${env.NUMBER_OF_PROCESSORS}&quot;/&gt;
   &lt;echo message=&quot;ANT_HOME is set to = ${env.ANT_HOME}&quot;/&gt;
 </pre>
 <p>reads the system environment variables and stores them in properties, prefixed with &quot;env&quot;.
 Note that this only works on <em>select</em> operating systems.
 Two of the values are shown being echoed.
 </p>

 <h3>Property Files</h3>

 As stated, this task will load in a properties file stored in the file
 system, or as a resource on a classpath. Here are some interesting facts
 about this feature
 <ol>
 <li>If the file is not there, nothing is printed except at -verbose log
 level. This lets you have optional configuration files for every
 project, that team members can customize.
 <li>The rules for this format are laid down
 <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/Properties.html#load(java.io.InputStream)">by Sun</a>.
 This makes it hard for Team Ant to field bug reports about it.
 <li>Trailing spaces are not stripped. It may have been what you wanted.
 <li>Want unusual characters? Escape them \u0456 or \" style.
 <li>Ant Properties are expanded in the file.
 </ol>
 In-file property expansion is very cool. Learn to use it.
 <p>
 Example:
 <pre>
 build.compiler=jikes
 deploy.server=lucky
 deploy.port=8080
 deploy.url=http://${deploy.server}:${deploy.port}/
 </pre>


 <hr>
 <p align="center">Copyright &copy; 2000-2003 Apache Software Foundation. All rights
 Reserved.</p>
 </body>
 </html>
	<html>

	<head>
	<meta http-equiv="Content-Language" content="en-us">
	<title>Property Task</title>
	<link rel="stylesheet" type="text/css" href="../stylesheets/antmanual.css">
	</head>

	<body>

	<h2><a name="property">Property</a></h2>
	<h3>Description</h3>
	<p>Sets a property (by name and value), or set of properties (from file or
	resource) in the project. Properties are case sensitive.</p>
	Properties are immutable: whoever sets a property first freezes it for the
	rest of the build; they are most definately not variable.
	<p>There are six ways to set properties:</p>
	<ul>
	<li>By supplying both the <i>name</i> and <i>value</i> attribute.</li>
	<li>By supplying both the <i>name</i> and <i>refid</i> attribute.</li>
	<li>By setting the <i>file</i> attribute with the filename of the property
	file to load. This property file has the format as defined by the file used
	in the class java.util.Properties, with the same rules about how
	non-ISO8859-1 characters must be escaped.</li>
	<li>By setting the <i>url</i> attribute with the url from which to load the
	properties. This url must be directed to a file that has the format as defined
	by the file used in the class java.util.Properties.</li>
	<li>By setting the <i>resource</i> attribute with the resource name of the
	property file to load. A resource is a property file on the current
	classpath, or on the specified classpath.</li>
	<li>By setting the <i>environment</i> attribute with a prefix to use.
	Properties will be defined for every environment variable by
	prefixing the supplied name and a period to the name of the variable.</li>
	</ul>
	<p>Although combinations of these ways are possible, only one should be used
	at a time. Problems might occur with the order in which properties are set, for
	instance.</p>
	<p>The value part of the properties being set, might contain references to other
	properties. These references are resolved at the time these properties are set.
	This also holds for properties loaded from a property file.</p>
	<p>A list of predefined properties can be found <a
	href="../using.html#built-in-props">here</a>.</p>

	<h4>OpenVMS Users</h4>
	<p>With the <code>environment</code> attribute this task will load all defined
	logicals on an OpenVMS system. Logicals with multiple equivalence names get
	mapped to a property whose value is a comma separated list of all equivalence
	names. If a logical is defined in multiple tables, only the most local
	definition is available (the table priority order being PROCESS, JOB, GROUP,
	SYSTEM).
	</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">name</td>
	<td valign="top">the name of the property to set.</td>
	<td valign="top" align="center">No</td>
	</tr>
	<tr>
	<td valign="top">value</td>
	<td valign="top">the value of the property.</td>
	<td valign="middle" align="center" rowspan="3">One of these, when using the
	name attribute</td>
	</tr>
	<tr>
	<td valign="top">location</td>
	<td valign="top">Sets the property to the absolute filename of the
	given file. If the value of this attribute is an absolute path, it
	is left unchanged (with / and \ characters converted to the
	current platforms conventions). Otherwise it is taken as a path
	relative to the project's basedir and expanded.</td>
	</tr>
	<tr>
	<td valign="top">refid</td>
	<td valign="top"><a href="../using.html#references">Reference</a> to an object
	defined elsewhere. Only yields reasonable results for references
	to <a href="../using.html#path">PATH like structures</a> or properties.</td>
	</tr>
	<tr>
	<td valign="top">resource</td>
	<td valign="top">the resource name of the property file.</td>
	<td valign="middle" align="center" rowspan="4">One of these, when
	<b>not</b> using the name attribute</td>
	</tr>
	<tr>
	<td valign="top">file</td>
	<td valign="top">the filename of the property file .</td>
	</tr>
	<tr>
	<td valign="top">url</td>
	<td valign="top">the url from which to read properties.</td>
	</tr>
	<tr>
	<td valign="top">environment</td>
	<td valign="top">the prefix to use when retrieving environment variables. Thus
	if you specify environment="myenv" you will be able to access OS-specific
	environment variables via property names "myenv.PATH" or
	"myenv.TERM". Note that if you supply a property name with a final
	"." it will not be doubled. ie environment="myenv." will still
	allow access of environment variables through "myenv.PATH" and
	"myenv.TERM". This functionality is currently only implemented
	on select platforms. Feel free to send patches to increase the number of platforms
	this functionality is supported on ;).<br>
	Note also that properties are case sensitive, even if the
	environment variables on your operating system are not, e.g. it
	will be ${env.Path} not ${env.PATH} on Windows 2000.</td>

	</tr>
	<tr>
	<td valign="top">classpath</td>
	<td valign="top">the classpath to use when looking up a resource.</td>
	<td align="center" valign="top">No</td>
	</tr>
	<tr>
	<td valign="top">classpathref</td>
	<td valign="top">the classpath to use when looking up a resource,
	given as <a href="../using.html#references">reference</a> to a <path> defined
	elsewhere..</td>
	<td align="center" valign="top">No</td>
	</tr>
	<tr>
	<td valign="top">prefix</td>
	<td valign="top">Prefix to apply to properties loaded using <code>file</code>
	or <code>resource</code>. A "." is appended to the prefix if not specified.</td>
	<td align="center" valign="top">No</td>
	</tr>
	</table>
	<h3>Parameters specified as nested elements</h3>
	<h4>classpath</h4>
	<p><code>Property</code>'s <i>classpath</i> attribute is a <a
	href="../using.html#path">PATH like structure</a> and can also be set via a nested
	<i>classpath</i> element.</p>
	<h3>Examples</h3>
	<pre> <property name="foo.dist" value="dist"/></pre>
	<p>sets the property <code>foo.dist</code> to the value "dist".</p>
	<pre> <property file="foo.properties"/></pre>
	<p>reads a set of properties from a file called "foo.properties".</p>
	<pre> <property url="http://www.mysite.com/bla/props/foo.properties"/></pre>
	<p>reads a set of properties from the address "http://www.mysite.com/bla/props/foo.properties".</p>
	<pre> <property resource="foo.properties"/></pre>
	<p>reads a set of properties from a resource called "foo.properties".</p>
	<p>Note that you can reference a global properties file for all of your Ant
	builds using the following:</p>
	<pre> <property file="${user.home}/.ant-global.properties"/></pre>
	<p>since the "user.home" property is defined by the Java virtual machine
	to be your home directory. Where the "user.home" property resolves to in
	the file system depends on the operating system version and the JVM implementation.
	On Unix based systems, this will map to the user's home directory. On modern Windows
	variants, this will most likely resolve to the user's directory in the "Documents
	and Settings" folder. Older windows variants such as Windows 98/ME are less
	predictable, as are other operating system/JVM combinations.</p>

	<pre>
	<property environment="env"/>
	<echo message="Number of Processors = ${env.NUMBER_OF_PROCESSORS}"/>
	<echo message="ANT_HOME is set to = ${env.ANT_HOME}"/>
	</pre>
	<p>reads the system environment variables and stores them in properties, prefixed with "env".
	Note that this only works on <em>select</em> operating systems.
	Two of the values are shown being echoed.
	</p>

	<h3>Property Files</h3>

	As stated, this task will load in a properties file stored in the file
	system, or as a resource on a classpath. Here are some interesting facts
	about this feature
	<ol>
	<li>If the file is not there, nothing is printed except at -verbose log
	level. This lets you have optional configuration files for every
	project, that team members can customize.
	<li>The rules for this format are laid down
	<a href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/Properties.html#load(java.io.InputStream)">by Sun</a>.
	This makes it hard for Team Ant to field bug reports about it.
	<li>Trailing spaces are not stripped. It may have been what you wanted.
	<li>Want unusual characters? Escape them \u0456 or \" style.
	<li>Ant Properties are expanded in the file.
	</ol>
	In-file property expansion is very cool. Learn to use it.
	<p>
	Example:
	<pre>
	build.compiler=jikes
	deploy.server=lucky
	deploy.port=8080
	deploy.url=http://${deploy.server}:${deploy.port}/
	</pre>


	<hr>
	<p align="center">Copyright © 2000-2003 Apache Software Foundation. All rights
	Reserved.</p>
	</body>
	</html>