org.springframework.beans.factory.UnsatisfiedDependencyException，没有类型为[edu.sample.service.ItemService]的合格Bean。

它是Spring Boot应用程序。我低于exception.how解决它，请帮助我我的Controller类是

import edu.sample.model.Item;
import edu.sample.service.ItemService;

@ComponentScan(basePackages = "edu.*")
@RestController
public class ItemController {

    @Autowired
    @Qualifier(value="itemService")
    private ItemService itemService;

    @RequestMapping(value = "/getAllItems", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<List<Item>> getAllItems() {
        List<Item> items = itemService.getAllItems();
        return new ResponseEntity<List<Item>>(items, HttpStatus.OK);
    }
}

服务等级为

@Service
public class ItemServiceImpl implements ItemService {

    @Autowired
    ItemDAO itemDAO;

    @Override
    public String addItem(Item item) {
        return itemDAO.addItem(item);
    }

    @Override
    public String deleteItem(Integer id) {
        return itemDAO.deleteItem(id);
    } 

    @Override
    public void updateItem(Item item) {

    }

    @Override
    public List<Item> getAllItems() {
        return itemDAO.getAllItems();
    }

}

和DAO类

@Resource
public class ItemDAOImpl implements ItemDAO {

    @PersistenceContext
    EntityManager entityManager;

    @Override
    public String addItem(Item item) {
        entityManager.persist(item);
        return item.getName();
    }

    @Override
    public String deleteItem(Integer id) {
        String name=entityManager.find(Item.class, id).getName();
        entityManager.remove(id);
        return name;
    }

    @Override
    public void updateItem(Item item) {

    }

    @Override
    public List<Item> getAllItems() {
        return entityManager.createQuery("from Item").getResultList();
    }

}

我收到此异常消息：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'itemController': Unsatisfied dependency expressed through field 'itemService': No qualifying bean of type [edu.sample.service.ItemService] found for dependency [edu.sample.service.ItemService]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=itemService)}; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [edu.sample.service.ItemService] found for dependency [edu.sample.service.ItemService]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=itemService)}