I have code that looks like follows:
public interface BaseDAO{
// marker interface
}
public interface CustomerDAO extends BaseDAO{
public void createCustomer();
public void deleteCustomer();
public Customer getCustomer(int id);
// etc
}
public abstract class DAOFactory {
public BaseDAO getCustomerDAO();
public static DAOFactory getInstance(){
if(system.getProperty("allowtest").equals("yes")) {
return new TestDAOFactory();
}
else return new ProdDAOFactory();
}
public class TestDAOFactory extends DAOFactory{
public BaseDAO getCustomerDAO() {
return new TestCustomerDAO(); // this is a concrete implementation
//that extends CustomerDAO
//and this implementation has dummy code on methods
}
public class ProdDAOFactory extends DAOFactory {
public BaseDAO getCustomerDAO() {
return new ProdCustomerDAO(); // this implementation would have
// code that would connect to the database and do some stuff..
}
}
Now, I do know that this code smells.. for many reasons. However, this code is here too: http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html, refer 9.8
What I intend to do is this: 1) Switch my DAOs implementations at runtime based on environment (system properties). 2) Make use of java generics so that I can avoid type casting... for instance does something like this:
CustomerDAO dao = factory.getCustomerDAO();
dao.getCustomer();
As opposed to:
CustomerDAO dao = (CustomerDAO) factory.getCustomerDAO();
dao.getCustomer();
Your thoughts and suggestions, please.