使用ANT在一个非常大的项目中生成.jar

I have a large project I'm working on (using Eclipse) that uses the 1.5 update 18 JDK, various external JARs, and the like. It's all been setup properly in Eclipse. Is it possible to create an Ant file that generates a JAR from a particular source file in my project? (A number of the source files are compilable into Java Applications. All of those share a lot of the same resources, thus the huge project workspace).I have a large project I'm working on (using Ec