Your question is two big. I don't think I can give a satisfactory answer.

Of course, you need use JDBC.

It is difficult to save an object into a database. Database can only save numbers, chars (String in Java), Blobs ... If you have an object, you need to express it in numbers, Strings, Iamges...before you store it into database.

Can you save(serialize) your objects into files?

Good luck.