Java library for code analysis

Is there any Java library, that can help in building AST from the specified java source file and vice versa (generate code from the ASTree o开发者_如何转开发bject)? I need something like this, but with an API, allowing to access the generated tree programmatically.

Everything's already available within the Eclipse core. Here's a page with a small example of how to use org.eclipse.jdt.core.dom.ASTParser to create your desired AST datastructure.