CODEWITHSUNDEEP
classloaderaspectj
b9xcc
b9xcc

Reputation: 41

Does AspectJ support modifying the JDK bytecode?

I want to intercept ClassLoader's loadClass method. In order to show the process of loading class by ClassLoader. But I don't know the working principle of aspectj. It can modify the source code of the JDK?

Upvotes: 0

Views: 229

Answers (1)

kriegaex
kriegaex

Reputation: 67297

You could just use a debugger and step through the process in order to understand it.

AspectJ can weave aspects into existing class files during compilation (CTW, compile-time weaving) or during class-loading (LTW, load-time weaving).

LTW does not work for JDK classes because those classes are always loaded before the weaving agent. So you have a bootstrapping problem there.

What you can do, however, is to apply CTW to the class files in e.g. rt.jar from your JRE/JDK distribution, zip the woven class files into another JAR and replace the original one with it. Then if you start the JVM with aspectjrt.jar on the boot classpath, you see the aspects in action. I have done that before and it works. But really, this is not what AspectJ was designed for. But you asked, so I told you. It is a very advanced topic though, and I doubt that it is the road you should take as a complete AspectJ greenhorn - no offense meant.

Update: Because I have been asked this question so often, I created a little demo project showing how to weave aspects into the JRE/JDK. I still do not think it makes sense to use it under normal circumstances, but what the heck: Why do people climb the Mount Everest? Because it exists. ;-)

Upvotes: 1

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