I have posted this several times, but couldn't get an answer. Could any one please throw some light on this?

If I pass an object to Session and save it, internally, the Hibernate API gets

1) class name of the object
2) then insert the data to DB

Instead of having a class defined for the above purpose, can I have an interface, create an object at runtime with the interface and save that particular object?

What do I need to subclass in Hibernate API so that I can achieve the above?

In other words, I use proxy objects / dynamic proxy objects / maps. I will pass these to the Session and save. To make this work, what are the classes I need to subclass / and methods I need to override?

Don't get you. You can map interfaces with hibernate just as you would map classes.

The objects that I create and populate will be a dynamic proxy objects / map proxy. This proxy object will implement my interface.

Class names for dynamic proxies (java.lang.reflect.Proxy) are generated and as I understand there is no way to map class with unknown name.
I am not sure, but looks like there is no way to use custom factory, hibernate uses "Class.newInstance()"
But looks like it is possible to use Map as entity in hibernate too, you can implement decorator for session interface and create adapters for map->proxy and proxy->map.
BTW Why do you need interfaces, proxies, maps for trivial data structure like entity ?

First I would answer to your question. I use Maps and proxy objects in my UI layer. I pass the same to the business layer. I wanted to use the same in my DAO layer as well.

If I dont use a separate DAO object, I can

Improve performance as I avoid copy of data from Map / proxy object to DAO object.
I would avoid creating lot of objects and lot of java files.

If Hibernate can give it as a map (while retrieving) and accept it as a map (while saving), its more than enough. With the variable name as the key

Eg: For a user having 2 fields namely id and name, the map would contain

{userId=1232, userName=