Ant - Property Files

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Setting properties directly in the build file is okay if you are working with a handful of properties. However, for a large project, it makes sense to store the properties in a separate property file.

Storing the properties in a separate file allows you to reuse the same build file, with different property settings for different execution environment. For example, build properties file can be maintained separately for DEV, TEST and PROD environments.

Specifying properties in a separate file is useful when you do not know the values for a property (in a particular environment) up front. This allows you to perform the build in other environments where the property value is known.

There is no hard and fast rule, but typically the property file is named build.properties and is placed along side the build.xml file. You could create multiple build properties file based on the deployment environments - such as build.properties.dev and build.properties.test

The contents of the build property file are similar to the normal java property file. They contain one property per line. Each property is represented by a name and a value pair. The name and value pair are separated by an equals sign. It is highly recommended that the properties are annotated with proper comments. Comments are listed using the hash character.

The following shows a build.xml and an associated build.properties file

build.xml

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

build.properties

# The Site Name
sitename=www.tutorialspoint.com
buildversion=3.3.2

In the above example, sitename is a custom property which is mapped to the site's name, You could declare any number of custom properties in this fashion. Another custom property listed in the above example is the buildversion, which, in this instance refers to the version of the build.

In addition to the above, ant comes with a number of predefined build properties, which have been listed in the previous section, but is represented below once again.

PropertiesDescription
ant.fileThe full location of the build file
ant.versionThe version of the Apache Ant installation
basedirThe basedir of the build, as specified in the basedir attribute of the project element.
ant.java.versionThe version of the JDK that is used by Ant.
ant.project.nameThe name of the project, as specified in the name atrribute of the project element.
ant.project.default-targetThe default target of the current project
ant.project.invoked-targetsComma separated list of the targets that were invoked in the current project
ant.core.libThe full location of the ant jar file
ant.homeThe home directory of Ant installation
ant.library.dirThe home directory for Ant library files - typically ANT_HOME/lib folder.

In the example presented in this section, we have used the ant.version built in property.



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