使用Hibernate和Spring的通用DAO是他们比这更好的方法吗？

Question

public class GenericDao <T, PK extends Serializable> {

    private final Class<T> type;

    @Resource(name = "sessionFactory")
    private SessionFactory sessionFactory;

    public GenericDao(final Class<T> type) {
    this.type = type;
    }

    public PK save(final T o) {
    return (PK) sessionFactory.getCurrentSession().save(o);
    }
// ... get,delete, etc

App上下文bean:

<bean id="fooDao" class="com.mycompany.dao.GenericDao">
        <constructor-arg>
            <value>com.mycompany.Foo</value>
        </constructor-arg>
    </bean>

并在服务层调用如下:

@Autowired
private GenericDao<Foo, Integer> fooDao;
...
public doStuffIncludingSave(Foo foo)
fooDao.save(foo);

Answer 1

一个好的起点是这篇Generic DAO文章,它来自2006年,但它有一些很好的信息.要更新Spring的常规DAO,hibernate和注释,这就是我所做的.这篇新文章也很有用.

所有标识符都是一个通用的接口,以确保该类具有I getId()和setId(I id)

创建通用DAO接口

public interface GenericDao<T extends Identifier<I>, I extends Serializable> {
    public T find(I id);
    public void delete(T obj);
    public void saveOrUpdate(T obj);
}

创建GenericDAO实施

public abstract class GenericDaoImpl<T extends Identifier<I>, I extends Serializable> implements GenericDao<T, I>{

    private Class<T> type;

    @Autowired
    private SessionFactory sessionFactory;
    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }
    protected SessionFactory getSessionFactory() {
        if (sessionFactory == null)
            throw new IllegalStateException("SessionFactory has not been set on DAO before usage");
        return sessionFactory;
    }

    public Class<T> getType() {
        return type;
    }

    public GenericDaoImpl() {
        this.type = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
    }

    @Transactional(readOnly = true)
    @Override
    public T find(I id) {
        return (T) getSessionFactory().getCurrentSession().get(getType(), id);
    }

    @Transactional
    @Override
    public void delete(T obj) {
        getSessionFactory().getCurrentSession().delete(obj);
    }

    @Transactional
    @Override
    public void saveOrUpdate(T obj) {
        getSessionFactory().getCurrentSession().saveOrUpdate(obj);
    }
}

对象DAO接口:

public interface SomeObjectDao extends GenericDao<SomeObject, Long>{
}

对象DAO实现

@Repository
public class SomeObjectDaoImpl extends GenericDaoImpl<SomeObject, Long> implements SomeObjectDao {

}

现在在需要它的任何类中,就像服务类一样,你可以通过添加你需要的对象类dao来获得自动装配

@Autowired
private SomeObjectDao someObjectDao;