From the comments, it looks like you are trying to do more than just parsing, you actually want to get some form of content assist.
I'm afraid that you're asking for too much. There is no simple way to get the power and flexibility of JDT outside of a running Eclipse instance (believe me, I've tried). There's no simple way, but if you are brave and strong willed, you can one of try following:
- Run a headless Eclipse on your server that works on top of an actual workspace. This would be the easiest to implement, but would be the most resource intensive and least flexible way of doing things.
- Use the jdt core jar, and create alternate implementations of the IResource hierarchy, and the parts of JFace that are used by the the parser and the CompletionEngine. This would likely be the most feature-rich way to go, but also the most brittle. I can't guarantee that this would work as you may need to create some very complex stubs for internal Eclipse non-API classes.
- Avoid the CompletionEngine and the ASTParser entirely and just use the batch compiler. You would then need to provide an alternate implementation of
org.eclipse.jdt.internal.compiler.env.INameEnvironment. This implementation would be able to find types, files, and compilation units in your actual project structure. You'd need to reimplement support for content assist, but this would most likely work reasonably well.
I am actually fairly interested in doing something like this (but I lack the time to do it). If you are seriously considering creating a headless JDT that can run on a server, feel free to ask for more information. I am quite familiar with JDT internals.