DAO Pattern Question

[Varun Chopra]

Friends,

I wanted to ask,

why do we need java interfaces for DAOs? I mean instead of coming through CustomerDAOInterface, if I access CustomerDAO directly from sessionbean/service-layer, what's wrong with it? If I need to add a new method in future, I can still add it to CustomerDAO, if I need to change a method in CustomerDAO I can do that. If I need to use a different persistence package I still will be working with CustomerDAO class only in both the cases.

So why should I use interface for DAO classes?


regards
VC

[Mark Spritzler]

Interfaces for all classes is just good OO for separation of concerns and High Cohesion, Low Coupling. It also allows something like Spring to inject these objects into your services instead of having to couple the DAO to you service.

Mark