Log4j property file from java app

Hello Friends
I am trying to run an ant task for running java applicaiton. Now in the java application i am using property configurator. In order for the property
configurator to work i have to pass to it a log.properties file reference
This file is inside /logging/log.properties location relative to the
any build.xml. Please can you tell me how to refer to this file from inside the java application in java way relatively,?

The below code did not work..
PropertyConfigurator.configure(ClassLoader.getSystemResource("log.properties"));

Thanks
Farouk