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Ant属性任务

Ant构建文件是用XML编写的，它不迎合声明变量，你在最喜欢的编程语言做的。然而，正如你可能已经想到，它会如果允许Ant声明变量，如项目名称，项目源代码目录等有用

Ant使用属性元素，它允许你指定的属性。这允许属性从一个版本改变为另一个。或者从一个环境到另一个。

默认情况下，Ant提供了可以在构建文件中使用下列预定义的属性

属性	描述
ant.file	The full location of the build file.
ant.version	The version of the Apache Ant installation.
basedir	The basedir of the build, as specified in the basedir attribute of theproject element.
ant.java.version	The version of the JDK that is used by Ant.
ant.project.name	The name of the project, as specified in the name atrribute of theproject element
ant.project.default-target	The default target of the current project
ant.project.invoked-targets	Comma separated list of the targets that were invoked in the current project
ant.core.lib	The full location of the ant jar file
ant.home	The home directory of Ant installation
ant.library.dir	The home directory for Ant library files - typically ANT_HOME/lib folder.

Ant也使得系统性能（例如：文件分割符），可用于构建文件。

除了以上所述，用户可以使用属性元素定义附加属性。一个例子介绍如下展示了如何定义一个名为站点名称（sitename）属性：

 <?xml version="1.0"?> <project name="Hello World Project" default="info">   <property name="sitename" value="www.yiibai.com"/>    <target name="info">    <echo>Apache Ant version is ${ant.version} - You are     at ${sitename} </echo>    </target> </project>

上述构建文件运行ant应该产生下面的输出：

 C:/>ant Buildfile: C:/build.xml  info:      [echo] Apache Ant version is Apache Ant(TM) version 1.8.2       compiled on December 20 2010 - You are at www.yiibai.com  BUILD SUCCESSFUL Total time: 0 seconds C:/>