Question

I’m using Eclipse Juno IDE and phpMyAdmin.

I have java application, for this application I created a DB in phpMyAdmin.
Now, I have an interface for the DB methods..
Lets say the interface is like that:

public interface DBInterface{
  public Vector<Employees> getAllEmplyess();
  public void addNewEmployee(int ID, String name,String department);
}

Now I need to implements this interface in two ways:

1) JPA

2) JDBC

Lets say that I implemented the interface in the two ways mentioned above.

How can I choose between the with the spring mechanism in the applicationContext.xml file?
How does it work?

Answer 1

Why do you need both JPA and JDBC implementations (JPA is based on JDBC)?

The way to distinguish between the two is to create 2 separate DAO classes (both implement your interface)

public class JDBCDao implements DBInterface {...}
public class JPADao implements DBInterface {...}

and inject an appropriate DAO bean in spring xml (application-context file) when needed.

For example the application context xml will look something like:
(dao member of the EmployeeService class is of type DBInterface)

<bean id="JPADAO" class="com.yourpackage.JPADao".../>
<bean id="JDBCDAO" class="com.yourpackage.JDBCDao".../>

<bean id="EmployeeService" class ....>
    <property name="dao" ref="JDBCDAO" />
    ...
</bean>

or alternatively you can inject the DAO in code.

ApplicationContext ctx = AppContext.getApplicationContext();  
EmployeeService svc = (EmployeeService) ctx.getBean("EmployeeService");  
DBInterface dao = (DBInterface) ctx.getBean("JPADAO");
svc.setDao(dao);