thecrumb.com

Tinking around with Ant I found out you can reference system environment properties within your build file.

So in Windows for example you can run SET at the command line and get a long list of properties:

U:\>set
ALLUSERSPROFILE=C:\Documents and Settings\All Users
ANT_HOME=D:\ant
APPDATA=C:\Documents and Settings\priestj\Application Data
CLIENTNAME=zappa

You can easily reference these in your build file – first set property environment to “env”:

<target name="echo">
<property environment="env"/>

</target>

Now we’ll add some of our Windows system properties (note these are case sensitive!):

<target name="echo">
<property environment="env"/>
<echo message="env.ALLUSERSPROFILE:   ${env.ALLUSERSPROFILE}" />
<echo message="env.ANT_HOME:   ${env.ANT_HOME}" />
<echo message="env.APPDATA:   ${env.APPDATA}" />
<echo message="env.CLIENTNAME:   ${env.CLIENTNAME}" /> </target>

Running this we can see these properties are picked up by Ant!

Buildfile: D:\build.xml
echo:
[echo] env.ALLUSERSPROFILE:   C:\Documents and Settings\All Users
[echo] env.ANT_HOME:   C:\eclipse\plugins\org.apache.ant_1.7.0.v200803061910
[echo] env.APPDATA:   C:\Documents and Settings\priestj\Application Data
[echo] env.CLIENTNAME:   zappa

I’m working on a build file for the Model-Glue project and want to make it as user friendly as possible.  Turns out this is very easy in Ant!

First always include a description in your build file – you can be a bit more verbose, I kept this short for the example:

<description>
Ant script to create new Model-Glue 3.0 application.
</description>

Of course if anyone edits your build file they will see the description, but we can also display this when the build file is first run. First I make my default target ‘help’:

<project name="Model-Glue" default="help" basedir=".">

Then create a ‘help’ target:

<target name="HELP" description="Displays a list of help to the user.">
<java fork="no" classname="org.apache.tools.ant.Main">
<classpath>
<fileset dir="${ant.home}\lib">
<include name="**/*.jar" />
</fileset>
</classpath>
<arg line="-projecthelp" />
</java>
</target>

This is simply running the exec task and running Ant with the ‘-p’ switch (which is short for ‘-projecthelp’ which simply prints a list of the build files targets as well as the description.  In all our other targets we’ll make sure to include a ‘description’:

<target name="build"  description="Copy Model-Glue files to new
project directory.">
<echo message="Copy Model-Glue!"/>
</target>

Now if we run our build file we’ll see something like the following output (either at the command line or in the Eclipse console:

D:\>ant
Buildfile: build.xml

help:
 [exec] Buildfile: build.xml
 [exec]
 [exec] Ant script to create new Model-Glue 3.0 application
 [exec]
 [exec] Main targets:
 [exec]
 [exec]  build  Copy Model-Glue files to new project directory.
 [exec]  help   Displays a list of help to the user.
 [exec] Default target: help

Now the user can easily determine the purpose of the build file and see a list of possible targets to run.