如何将参数传递给Ant的Junit测试？

I'm using Junit under Ant to perform Selenium Test.My test cases need to read files which contain test data(in order to accomplish data driven test). I don't mind embedding the file names in the test cases, but I'd like to have the name of the directory where the data files are stored parameterized in the build.xml file.I'm using Junit under Ant to perform Selenium T