Question

I have DAO’s for each table, that all implement an interface.

Now I want to be able to (potentially) swap database layer implementations.

So my strategy is to create a DaoFactory, and this DaoFactory will be specific to a particular implemenation of my DAO’s.

So I will have DAO’s for hibernate.
Then a DaoHibernateFactory that will look like:

public class DaoHibernateFactory implements DaoFactory
{


     public UserDao GetUserDao() {

          return new UserHibernateDao();
     }


}

Then in all my manager/service classes, I will use whichever Dao___Factory is currently wired via spring ioc.

Does this make sense? Suggestions?

Answer 1

I would have separate configuration files for each implementation, rather than using factories. That way spring can inject your DAOs for you, and you don’t have to call or maintain an extra factory class.

For example:

hibernate-data.xml:

<bean id="userDAO" class="com.foo.dao.hibernate.HibernateUserDao">
    ...
</bean>

ibatis-data.xml:

<bean id="userDAO" class="com.foo.dao.ibatis.IBatisUserDao">
    ...
</bean>

etc.

Then you can swap out the implementation by changing which -data file is included in your web.xml.