Spring 3 DI using generic DAO interface
- by Peders
I'm trying to use @Autowired annotation with my generic Dao interface like this:
public interface DaoContainer<E extends DomainObject> {
public int numberOfItems();
// Other methods omitted for brevity
}
I use this interface in my Controller in following fashion:
@Configurable
public class HelloWorld {
@Autowired
private DaoContainer<Notification> notificationContainer;
@Autowired
private DaoContainer<User> userContainer;
// Implementation omitted for brevity
}
I've configured my application context with following configuration
<context:spring-configured />
<context:component-scan base-package="com.organization.sample">
<context:exclude-filter expression="org.springframework.stereotype.Controller"
type="annotation" />
</context:component-scan>
<tx:annotation-driven />
This works only partially, since Spring creates and injects only one instance of my DaoContainer, namely DaoContainer. In other words, if I ask userContainer.numberOfItems(); I get the number of notificationContainer.numberOfItems()
I've tried to use strongly typed interfaces to mark the correct implementation like this:
public interface NotificationContainer extends DaoContainer<Notification> { }
public interface UserContainer extends DaoContainer<User> { }
And then used these interfaces like this:
@Configurable
public class HelloWorld {
@Autowired
private NotificationContainer notificationContainer;
@Autowired
private UserContainer userContainer;
// Implementation omitted...
}
Sadly this fails to BeanCreationException:
org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.organization.sample.dao.NotificationContainer com.organization.sample.HelloWorld.notificationContainer; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.organization.sample.NotificationContainer] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
Now, I'm a little confused how should I proceed or is using multiple Dao's even possible. Any help would be greatly appreciated :)
