Question

How can I get an already existing object spring managed? I would like to hook it up to Springs AoP capabilities using aspectj. I know this to be a challenge since Spring AoP uses dynamic proxies which probably are created along with the object.

Why do I need this?

I have a third-party class which takes a constructor argument which is only known in runtime,
hence it seems I cannot add it to my applicationContext or use springs FactoryBean interface for construction. Is there any other way?

I’ve already tried the following without great success:

Obj obj = new ThirdPartyObj("runtime constructor arg");
appContext.getAutowireCapableBeanFactory().initializeBean(obj, "Obj");

It might be spring-managed, but I still cannot use it to trigger aspects.

---

[EDIT] axtavt pointed out the problem is that I don’t use the object returned from initializeBean(..). Both mentioned approaches work, but only if:

• Using interface ObjInterface obj = (ObjInterface) ac.getBean("obj", args); or we will get a:

  java.lang.ClassCastException: $Proxy28 cannot be cast to com.company.Obj

• Not using interface but enable CGLIB. This requires a non-private default constructor, or we will get a:

  java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given

Answer 1

You should be able to trigger aspects using this (note that you need to use returned object which can be a proxy):

Obj obj = new ThirdPartyObj("runtime constructor arg");     
obj = appContext.getAutowireCapableBeanFactory().initializeBean(obj, "Obj"); 

Another option is to declare it as a regular bean and pass the constructor argument via getBean():

Obj obj = appContext.getBean("Obj", "runtime constructor arg");