I would like to generate POJO classes and the mapping file on the fly (in the runtime). Would you please give me sample source code to do this with

Hibernate version: 3.2

Hibernate Tools version: 3.2

Databaseversion: MySQL 5.x

I don't understand what you are asking for ?

How are you going to write code for thse classes and mappings if you don't have them at compile time ? ;)

I got the DataModel in the Database Schema already. Following is my approach (at runtime):
Schema -> Mapping Files (.hbm.xml) -> Pojo classes (.java)

Because the Pojo classes simply contain get/set method, I can invoke those methods at the runtime using Reflection API.

The purpose of following this approach is that at compile time I dont have to care about the entity, how it saved and loaded, because the entity is created at the runtime.

The entities and its relation are created at the run time and we design the database schema for it, then update DB. Then we start the program without changing any code because of the automated approach above. That's the whole idea about this.

so invoke reverse engineering, call hbm2java and compile the classes......

Nothing special, but also nothing that I would ever recommend doing if you want a performant system.

You can look into dynamic mapping of hibernate. But you can't do everything on the fly. You have to restart to got new fields/classes into the system.