Ant Properties File

You can also group all the property values in a separate properties file and include it in the ant build file. Here the build.properties file contains all the property values. Remember the property value is immutable, so if you set a property value in the properties file you cannot change it in the build file. This give more control over the build process.

The build.properties file.

web.dir=WebContent
web.lib.dir=${web.dir}/WEB-INF/lib
build.classes.dir=build/classes
dist.dir=dist
project.name=AntExample3

Use the property task to include the properties file in the Ant build file.

<property file="build.properties" />

Here is the complete build file for your reference.

<?xml version="1.0" ?> 
<project name="AntExample3" default="war">
	
	<property file="build.properties" />

	<path id="compile.classpath">
		<fileset dir="${web.lib.dir}">
			<include name="*.jar"/>
		</fileset>
	</path>
	
	<target name="init" depends="clean">
		<mkdir dir="${build.classes.dir}"/>
		<mkdir dir="${dist.dir}" />
	</target>
	
	<target name="compile" depends="init" >
		<javac destdir="${build.classes.dir}" debug="true" srcdir="src">
			<classpath refid="compile.classpath"/>
		</javac>
	</target>
	
	<target name="war" depends="compile">
		<war destfile="${dist.dir}/${project.name}.war" webxml="${web.dir}/WEB-INF/web.xml">
			<fileset dir="${web.dir}"/>
			<lib dir="${web.lib.dir}"/>
			<classes dir="${build.classes.dir}"/>
		</war>
	</target>
	
	<target name="clean">
		<delete dir="${dist.dir}" />
		<delete dir="${build.classes.dir}" />
	</target>
	
</project>

You can download the build file here.