Ant conditional branch

Ant conditional branch

I was working on a auto-build file using ant when I wanted to add some conditional branches in the file.

For example, I want to first check whether the environment variables have been set, if yes, then go on build, if not, just break the current build.

The script is like this:

<project name="Test Project" default="build">

<property environment="env" />

<target name="build" depends="path.check">

<echo> continue build </echo>

</target>

<target name="path.check" depends="checkpath" unless="all.variable.set">

<echo>env.JAVA_HOME=${env.JAVA_HOME}</echo>

<echo>env.ECLIPSE_HOME=${env.ECLIPSE_HOME}</echo>

<fail message="not all variables have been set or not set correctly." />

</target>

<target name="checkpath">

<condition property="all.variable.set">

<and>

<available file="${env.JAVA_HOME}" />

<available file="${env.ECLIPSE_HOME}" />

</and>

</condition>

</target>

</project>

The main point of the conditional branch is the "condition" element and the "unless" attribute in the <target>. Please refer to the Apache Ant website for more information.

In this script, we check whether the environment variable "JAVA_HOME" and "ECLIPSE_HOME" have been set, and also check whether the directory exists.

If you only want to test whether this variables have been set, you can change the <condition> block to this:

<condition property="all.variable.set">

    <and>

        <isset property="env.PROMPT" />

<isset property="env.SONIC_HOME" />

    </and>

</condition>

For more details about what you can do in the <condition> element, you can check  here.