Change default ant target by command line argument

Question

I'm recently assigned a task to make ant be able to build war packages for different environments.

And I'm almost done. Except one feature.

The ant accepts an env parameter by like -Denv=DEV, and use different configuration files to make the war package. But the default target is start which will build, deploy and start the tomcat. I don't want ant to deploy the war neither start the server when I pass in the -Denv=PROD arg. I only want ant to build the ROOT.war. It's enough.

I know I can just type one more word to achieve this goal, but you know we are all lazy. :D

Does anyone know how to change the default target according to the command line argument? My requirements are:

1. ant -Denv=DEV will build, deploy, and start the server
2. ant -Denv=PROD will only build the ROOT.war

Answer 1

You could also load different property files based on the env property:

<property file="${env}.properties"/>

and in there configure which target to call:

in DEV.properties:

default.target=dev.build

in PROD.properties:

default.target=prod.build

and then call the target based on the property:

<target name="default">
    <antcall target="${default.target}"/>
</target>

<target name="dev.build">
    ....
</target>

<target name="prod.build">
    ....
</target>

by specifying separate property files for each build type you will make it easy to configure other aspects of the build.

Answer 2

I suggest that you define targets in your build.xml file called "DEV" and "PROD" and then invoke Ant as:

ant DEV

or

ant PROD

If you want to stick with your current approach of using a system property to select the target, then @krock's answer seems to be the way to go. (But I don't see any advantage in that approach though.)

Answer 3

there is an "if"-Task in the ant-contrib collection. Using this you can define a default task, that tests for your parameter and calls the required tasks. You could also define a default behaviour if the dev param is not set.