RE: [picocontainer-dev] Constructor Injection and Serialization Patterns

Hi Michael,


  _____  

	From: Michael Rimov [mailto:[email protected]] 
	Sent: Tuesday, February 26, 2008 8:15 PM
	To: dev-qxt/[email protected]
	Subject: RE: [picocontainer-dev] Constructor Injection and Serialization Patterns
	
	

	Sorry for not getting it, but I don't think I understand how Objenesis would help with this problem?

	 

	What I want is to be able to:

	 

	ObjectInputStream ois = new ObjectInputStream( /* some input stream */ );

	Sample s = (Sample)ois.readObject();

	 

	/* And then a miracle occurs! */

	 

	assert s.getClassLoader() != null;

	 

	And somehow have Sample useful, even if the classloader specified in the constructor would have to be transient. (Or just not saved via custom serialization/externalization).  

	 

	So far, the only things I can think of are atatic containers and have class Sample read its own dependencies during readObject()... which of course, breaks everything in the Pico book in only one function. :-) 

Not really, since serialization is also not covered by DI. :)

Since it is the DI container that is normally repsonsible for creating a new object, you're in conflict with the serialization anyway.

 

Therefore I'd make the ClassLoader transient.

	Does this clarify my problem?  I suspect this isn't really anything Pico can solve per-se, rather a standard pattern for dealing with this problem would be a good thing to document. 

The readResolve method will not realy solve your problem, since you'll have to get the correct ClassLoader form somewhere also. For the Pico way I can only think of a SerializingTransiendFieldInjector i.e. a factory that creates an object from an object stream and does a field injection for all transient fields (handle them as if they are the dependencies). However, where does now the object stream come from ?

 

- Jörg