Poor man's O/R mapping

Question

I am curious to know how others have mapped their database tables to java beans used to represent them. I have created an XML file that ties them both together and just read that XML file to assist in generating SQL Statements. I am still in the process of creating this "framework" if it even warrants the name. How have other solved this all too common problem?
ps. I really don't want to use a large Object Relational Framework like Hibernate mostly because I don't want to take the time to learn it and add complexity to my first database centric web application.
Thanks,
-Brian

Answer 1

Its a pretty small system, only about 15 database
tables with the same number of java beans to store
the data. That's not many. Especially since this is your first web app, I'd recommend just going straight JDBC. If the tables and objects map 1:1 they'll be easy to persist.
Start with a clearly defined persistence layer. Use what's known as the Data Access Object, which begins with an interface. If you have a model object Foo, you'll write a DAO for it like this:
package persistence;
public interface FooDao
   Foo find(long id);
   List findAll();
   void saveOrUpdate(Foo foo);
   void delete(Foo foo);
}The id is the primary key for your Foo object. If you have other search criteria (e.g., last name for a Person object), add additional find methods.
The beauty of this approach is that you can implement your FooDao interface as straight JDBC now, but later on when you become more sophisticated (e.g., Hibernate/Spring, etc.) you can change the implementation without affecting clients, because they'll continue to make calls to the interface.
Write a mapper class that takes a ResultSet and returns a Foo, one for every model object.
You can also see how easy it would be to use code generation here. Write a Velocity template or even a home-grown one that would interrogate your model package and spit out all the persistence interfaces and skeleton implementations for you.
Good luck. Come back if you think this is helpful and you have any other questions.
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