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| 3 | <head>
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| 4 | <meta http-equiv="Content-Language" content="en-us">
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| 5 | <title>Property Task</title>
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| 6 | <link rel="stylesheet" type="text/css" href="../stylesheets/antmanual.css">
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| 7 | </head>
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| 8 |
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| 9 | <body>
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| 10 |
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| 11 | <h2><a name="property">Property</a></h2>
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| 12 | <h3>Description</h3>
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| 13 | <p>Sets a property (by name and value), or set of properties (from file or
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| 14 | resource) in the project. Properties are case sensitive.</p>
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| 15 | Properties are immutable: whoever sets a property first freezes it for the
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| 16 | rest of the build; they are most definately not variable.
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| 17 | <p>There are six ways to set properties:</p>
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| 18 | <ul>
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| 19 | <li>By supplying both the <i>name</i> and <i>value</i> attribute.</li>
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| 20 | <li>By supplying both the <i>name</i> and <i>refid</i> attribute.</li>
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| 21 | <li>By setting the <i>file</i> attribute with the filename of the property
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| 22 | file to load. This property file has the format as defined by the file used
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| 23 | in the class java.util.Properties, with the same rules about how
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| 24 | non-ISO8859-1 characters must be escaped.</li>
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| 25 | <li>By setting the <i>url</i> attribute with the url from which to load the
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| 26 | properties. This url must be directed to a file that has the format as defined
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| 27 | by the file used in the class java.util.Properties.</li>
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| 28 | <li>By setting the <i>resource</i> attribute with the resource name of the
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| 29 | property file to load. A resource is a property file on the current
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| 30 | classpath, or on the specified classpath.</li>
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| 31 | <li>By setting the <i>environment</i> attribute with a prefix to use.
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| 32 | Properties will be defined for every environment variable by
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| 33 | prefixing the supplied name and a period to the name of the variable.</li>
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| 34 | </ul>
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| 35 | <p>Although combinations of these ways are possible, only one should be used
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| 36 | at a time. Problems might occur with the order in which properties are set, for
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| 37 | instance.</p>
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| 38 | <p>The value part of the properties being set, might contain references to other
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| 39 | properties. These references are resolved at the time these properties are set.
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| 40 | This also holds for properties loaded from a property file.</p>
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| 41 | <p>A list of predefined properties can be found <a
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| 42 | href="../using.html#built-in-props">here</a>.</p>
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| 43 |
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| 44 | <h4>OpenVMS Users</h4>
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| 45 | <p>With the <code>environment</code> attribute this task will load all defined
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| 46 | logicals on an OpenVMS system. Logicals with multiple equivalence names get
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| 47 | mapped to a property whose value is a comma separated list of all equivalence
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| 48 | names. If a logical is defined in multiple tables, only the most local
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| 49 | definition is available (the table priority order being PROCESS, JOB, GROUP,
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| 50 | SYSTEM).
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| 51 | </p>
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| 52 |
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| 53 | <h3>Parameters</h3>
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| 54 | <table border="1" cellpadding="2" cellspacing="0">
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| 55 | <tr>
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| 56 | <td valign="top"><b>Attribute</b></td>
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| 57 | <td valign="top"><b>Description</b></td>
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| 58 | <td align="center" valign="top"><b>Required</b></td>
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| 59 | </tr>
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| 60 | <tr>
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| 61 | <td valign="top">name</td>
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| 62 | <td valign="top">the name of the property to set.</td>
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| 63 | <td valign="top" align="center">No</td>
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| 64 | </tr>
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| 65 | <tr>
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| 66 | <td valign="top">value</td>
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| 67 | <td valign="top">the value of the property.</td>
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| 68 | <td valign="middle" align="center" rowspan="3">One of these, when using the
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| 69 | name attribute</td>
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| 70 | </tr>
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| 71 | <tr>
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| 72 | <td valign="top">location</td>
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| 73 | <td valign="top">Sets the property to the absolute filename of the
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| 74 | given file. If the value of this attribute is an absolute path, it
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| 75 | is left unchanged (with / and \ characters converted to the
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| 76 | current platforms conventions). Otherwise it is taken as a path
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| 77 | relative to the project's basedir and expanded.</td>
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| 78 | </tr>
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| 79 | <tr>
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| 80 | <td valign="top">refid</td>
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| 81 | <td valign="top"><a href="../using.html#references">Reference</a> to an object
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| 82 | defined elsewhere. Only yields reasonable results for references
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| 83 | to <a href="../using.html#path">PATH like structures</a> or properties.</td>
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| 84 | </tr>
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| 85 | <tr>
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| 86 | <td valign="top">resource</td>
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| 87 | <td valign="top">the resource name of the property file.</td>
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| 88 | <td valign="middle" align="center" rowspan="4">One of these, when
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| 89 | <b>not</b> using the name attribute</td>
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| 90 | </tr>
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| 91 | <tr>
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| 92 | <td valign="top">file</td>
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| 93 | <td valign="top">the filename of the property file .</td>
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| 94 | </tr>
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| 95 | <tr>
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| 96 | <td valign="top">url</td>
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| 97 | <td valign="top">the url from which to read properties.</td>
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| 98 | </tr>
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| 99 | <tr>
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| 100 | <td valign="top">environment</td>
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| 101 | <td valign="top">the prefix to use when retrieving environment variables. Thus
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| 102 | if you specify environment="myenv" you will be able to access OS-specific
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| 103 | environment variables via property names "myenv.PATH" or
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| 104 | "myenv.TERM". Note that if you supply a property name with a final
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| 105 | "." it will not be doubled. ie environment="myenv." will still
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| 106 | allow access of environment variables through "myenv.PATH" and
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| 107 | "myenv.TERM". This functionality is currently only implemented
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| 108 | on select platforms. Feel free to send patches to increase the number of platforms
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| 109 | this functionality is supported on ;).<br>
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| 110 | Note also that properties are case sensitive, even if the
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| 111 | environment variables on your operating system are not, e.g. it
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| 112 | will be ${env.Path} not ${env.PATH} on Windows 2000.</td>
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| 113 |
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| 114 | </tr>
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| 115 | <tr>
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| 116 | <td valign="top">classpath</td>
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| 117 | <td valign="top">the classpath to use when looking up a resource.</td>
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| 118 | <td align="center" valign="top">No</td>
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| 119 | </tr>
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| 120 | <tr>
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| 121 | <td valign="top">classpathref</td>
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| 122 | <td valign="top">the classpath to use when looking up a resource,
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| 123 | given as <a href="../using.html#references">reference</a> to a <path> defined
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| 124 | elsewhere..</td>
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| 125 | <td align="center" valign="top">No</td>
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| 126 | </tr>
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| 127 | <tr>
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| 128 | <td valign="top">prefix</td>
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| 129 | <td valign="top">Prefix to apply to properties loaded using <code>file</code>
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| 130 | or <code>resource</code>. A "." is appended to the prefix if not specified.</td>
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| 131 | <td align="center" valign="top">No</td>
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| 132 | </tr>
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| 133 | </table>
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| 134 | <h3>Parameters specified as nested elements</h3>
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| 135 | <h4>classpath</h4>
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| 136 | <p><code>Property</code>'s <i>classpath</i> attribute is a <a
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| 137 | href="../using.html#path">PATH like structure</a> and can also be set via a nested
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| 138 | <i>classpath</i> element.</p>
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| 139 | <h3>Examples</h3>
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| 140 | <pre> <property name="foo.dist" value="dist"/></pre>
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| 141 | <p>sets the property <code>foo.dist</code> to the value "dist".</p>
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| 142 | <pre> <property file="foo.properties"/></pre>
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| 143 | <p>reads a set of properties from a file called "foo.properties".</p>
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| 144 | <pre> <property url="http://www.mysite.com/bla/props/foo.properties"/></pre>
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| 145 | <p>reads a set of properties from the address "http://www.mysite.com/bla/props/foo.properties".</p>
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| 146 | <pre> <property resource="foo.properties"/></pre>
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| 147 | <p>reads a set of properties from a resource called "foo.properties".</p>
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| 148 | <p>Note that you can reference a global properties file for all of your Ant
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| 149 | builds using the following:</p>
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| 150 | <pre> <property file="${user.home}/.ant-global.properties"/></pre>
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| 151 | <p>since the "user.home" property is defined by the Java virtual machine
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| 152 | to be your home directory. Where the "user.home" property resolves to in
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| 153 | the file system depends on the operating system version and the JVM implementation.
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| 154 | On Unix based systems, this will map to the user's home directory. On modern Windows
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| 155 | variants, this will most likely resolve to the user's directory in the "Documents
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| 156 | and Settings" folder. Older windows variants such as Windows 98/ME are less
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| 157 | predictable, as are other operating system/JVM combinations.</p>
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| 158 |
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| 159 | <pre>
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| 160 | <property environment="env"/>
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| 161 | <echo message="Number of Processors = ${env.NUMBER_OF_PROCESSORS}"/>
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| 162 | <echo message="ANT_HOME is set to = ${env.ANT_HOME}"/>
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| 163 | </pre>
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| 164 | <p>reads the system environment variables and stores them in properties, prefixed with "env".
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| 165 | Note that this only works on <em>select</em> operating systems.
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| 166 | Two of the values are shown being echoed.
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| 167 | </p>
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| 168 |
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| 169 | <h3>Property Files</h3>
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| 170 |
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| 171 | As stated, this task will load in a properties file stored in the file
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| 172 | system, or as a resource on a classpath. Here are some interesting facts
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| 173 | about this feature
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| 174 | <ol>
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| 175 | <li>If the file is not there, nothing is printed except at -verbose log
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| 176 | level. This lets you have optional configuration files for every
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| 177 | project, that team members can customize.
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| 178 | <li>The rules for this format are laid down
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| 179 | <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/Properties.html#load(java.io.InputStream)">by Sun</a>.
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| 180 | This makes it hard for Team Ant to field bug reports about it.
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| 181 | <li>Trailing spaces are not stripped. It may have been what you wanted.
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| 182 | <li>Want unusual characters? Escape them \u0456 or \" style.
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| 183 | <li>Ant Properties are expanded in the file.
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| 184 | </ol>
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| 185 | In-file property expansion is very cool. Learn to use it.
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| 186 | <p>
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| 187 | Example:
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| 188 | <pre>
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| 189 | build.compiler=jikes
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| 190 | deploy.server=lucky
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| 191 | deploy.port=8080
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| 192 | deploy.url=http://${deploy.server}:${deploy.port}/
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| 193 | </pre>
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| 194 |
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| 195 |
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| 196 | <hr>
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| 197 | <p align="center">Copyright © 2000-2004 The Apache Software Foundation. All rights
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| 198 | Reserved.</p>
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| 199 | </body>
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| 200 | </html>
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| 201 |
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