Instantiate default class loader more than once

Question

I have two versions of a dependence java library in a small part of a really big java spring project that I really have to use in combination for some time, however:

-the new version is not backward compatible with the older one

-both versions use the same class uris

Thus, I ended up trying to instatiate both library versions separately somehow because the default class loader keeps keeping the first instance and things are going crazy. I searched a little for some hours, many people recommend OSGi but I don't want to integrate all that framework just for this little. Also, I tried jarjar via maven but I didn's seem to work for the target dependency jars (I think they are obfuscated anyway). So, I am trying to simply instatiate a separate ClassLoader that can do the trick. Any of you know any trivial way to do that?

Answer 1

Can you encapsulate usage of the framework to small set of functions, that could be described by an interface?

If so, and if you are in an Application-Server Environment, you could do something like this:

Define your Interface and put it to the lib-Folder of your app-server with two factory-methods. Your app goes to WebArchive1 Framework in Version 1 goes to WebArchive2 and populates factory-method1 from your lib-Folder Framework in Version 2 goes to WebArchive3 and populates factory-method2 from your lib-Folder

--> lib
public interface MyInterface {
   // do Stuff
}

public class MyFactory {
  private static MyInterface v1;
  private static MyInterface v2;

  public MyInterface getV1() {...}
  public MyInterface getV1() {...}
}

--> WebArchive2
MyFactory.setV1(new Lib());

--> WebArchive3
MyFactory.setV2(new Lib());

Answer 2

Nevermind, problem fixed the easy way. I contacted the library authors and they refactored their old version package for me . So no class loader hacks needed anymore :)