How to set Ant properties based on variables in Eclipse?

Question

I have a common problem and there are probably countless ways to solve it. I'm looking for an elegant, simple solution to this typical scenario:

I have a project in Eclipse with an Ant build file (build.xml) the build file uses a property file (build.properties). In that property file, I want to set a property that points to the root directory of the eclipse project such as:

project.root = /path/to/eclipse/workspace/projectName

or preferably:

project.root = ${path.to.eclipse.workspace}/projectName

How do I do this in such a way that:

1. Works on different machines with different paths to the project root (i.e. in a team environment)
2. Allows the ant build.xml file to be executed inside eclipse
3. Allows the ant build.xml file to be executed outside of eclipse (i.e. from command line)
4. Allows the build.properties file to exist in a directory other than the project root

Answer 1

You can set eclipse relative properties for your ANT Build from eclipse

Go to your ANT Builder properties and in arguments section you can set properties using -D as below

-Dworkspace="${workspace_loc}" -Dproject_dir="${project_loc}"

(here workspace_loc and project_loc are eclipse variables). These properties can be accessed in your ANT build script like regular properties, for example:

<echo message="${workspace}" />
<echo message="${project_dir}" />

Answer 2

See Window -> Preferences -> Ant -> Runtime -> Properties to define custom ant properties that should be available to any ant script invoked from Eclipse. The simply set the same property manually when invoking script from command-line.

Your build.properties file can exist wherever you like. Use normal Ant facilities to import it into your script.