Injection of autowired dependencies failed - spring

Question

I'm trying to realize the same as in Spring error when trying to manage several classes that share a common base class?
But I'm still getting this Exception:
Error creating bean with name 'com.example.model.CategoryTest': Injection of
autowired dependencies failed; nested exception is
org.springframework.beans.factory.BeanCreationException: Could not autowire
field: private com.example.model.CategoryService
com.example.model.CategoryTest.service; nested exception is
org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean
of type [com.example.model.CategoryService] 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)}
Here are my classes in hope someone can help me understanding this autowiring stuff...
public abstract class BaseDAO<E>
{
public abstract void delete( int id );
public abstract void save( E entity );
public abstract List<E> list();
}
public abstract class BaseService<E, D extends BaseDAO<E>>
{
private final D dao;
protected BaseService( D dao )
{
this.dao = dao;
}
#Transactional
public void delete( int id )
{
dao.delete( id );
}
#Transactional
public void save( E entity )
{
dao.save( entity );
}
#Transactional
public List<E> list()
{
return dao.list();
}
}
#Repository
public class CategoryDAO extends BaseDAO<Category>
{
#Autowired
private SessionFactory sessionFactory;
#Override
public void delete( int id )
{
Category category = ( Category ) sessionFactory.getCurrentSession().load( Category.class, id );
if ( category != null )
{
sessionFactory.getCurrentSession().delete( category );
}
}
#Override
public void save( Category category )
{
sessionFactory.getCurrentSession().save( category );
}
#Override
public List<Category> list()
{
return sessionFactory.getCurrentSession().createQuery( "from Category" ).list();
}
}
#Service
public class CategoryService extends BaseService<Category, CategoryDAO>
{
#Autowired
public CategoryService( CategoryDAO dao )
{
super( dao );
}
}
UPDATE
Servlet context does contain this line: <context:component-scan base-package="com.example" />
Test context (I'm using maven) does contain this line: <context:annotation-config />
Replacing <context:annotation-config /> with <context:component-scan base-package="com.example" /> results in this Exception:
org.springframework.beans.factory.BeanCreationException: Could not autowire field:
private com.example.model.CategoryService
com.example.controller.ExampleController.categoryService;
nested exception is
org.springframework.beans.factory.BeanCreationException: Error creating bean
with name 'categoryService' defined in file
[/home/danny/example/target/classes/com/example/model/CategoryService.class]:
Initialization of bean failed; nested exception is
org.springframework.aop.framework.AopConfigException: Could not generate CGLIB
subclass of class [class com.example.model.CategoryService]: Common causes of
this problem include using a final class or a non-visible class; nested exception
is java.lang.IllegalArgumentException: Superclass has no null constructors but no
arguments were given
UPDATE2
I'm still getting this exception, here's my new code (only changed classes):
public abstract class BaseService<E, D extends BaseDAO<E>>
{
private D dao;
/*protected BaseService( D dao )
{
this.dao = dao;
}*/
protected BaseService(){}
protected void setDAO( D dao )
{
this.dao = dao;
}
#Transactional
public void delete( int id )
{
dao.delete( id );
}
#Transactional
public void save( E entity )
{
dao.save( entity );
}
#Transactional
public List<E> list()
{
return dao.list();
}
}
#Service
public class CategoryService extends BaseService<Category, CategoryDAO>
{
#Autowired
public CategoryService( CategoryDAO dao )
{
setDAO( dao );
}
}
UPDATE3
The solution:
public abstract class BaseService<E, D extends BaseDAO<E>>
{
protected D dao;
public BaseService()
{
}
protected D getDao()
{
return dao;
}
#Autowired
protected void setDAO( D dao )
{
this.dao = dao;
}
// ...
}
#Service
public class CategoryService extends BaseService<Category, CategoryDAO>
{
public CategoryService()
{
setDAO( dao );
}
}

Answer 1

It doesn't look like an instance of CategoryService is available for Spring to inject in the dependency into the test. You may be missing the component-scan in your services package - <context:component-scan base-package="..">
Update:
Based on your update, and this post - Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0' defined in ServletContext resource , it looks like you will have to change your BaseService, to have a setter for dao rather than set using a constructor. CGLIB with Spring AOP may not work well with a non default constructor

Answer 2

You should annotate your classes with #Component at least, for them to be eligible for autowired injection.