如何在Hibernate上实现GenericDAO类

Question

我希望UserDao类扩展GenericDAO，在那里我将拥有所有的CRUD方法。我读过IBM的文章：http://www.ibm.com/developerworks/java/library/j-genericdao/index.html，但我无法实现它。谁能给我展示一下基于我的自定义UserDao类的例子。

@Transactional(value="myTransactionManager")
public class UserDao {

    @Qualifier("mySessionFactory")
    public SessionFactoryImpl sessionFactory;

    public void setSessionFactory(SessionFactoryImpl sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    public List<UserEntity> getAll() {
        Query query = sessionFactory.getCurrentSession().createQuery(
                "from UserEntity ");
        List<UserEntity> userList = query.list();
        return userList;
    }

    public void updaet(UserEntity userEntity) {
        sessionFactory.getCurrentSession().update(userEntity);
    }

    public void delete(UserEntity userEntity) {
        sessionFactory.getCurrentSession().delete(userEntity);
    }

    public void save(UserEntity userEntity) {
        sessionFactory.getCurrentSession().save(userEntity);
    }

}

我试着像这样写类

public class GenericDao{

    @Qualifier("mySessionFactory")
    public SessionFactoryImpl sessionFactory;

    public void setSessionFactory(SessionFactoryImpl sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    public <T> List<T> getAll(Class<T> t) {
        Query query = sessionFactory.getCurrentSession().createQuery(
                "from " + t.getName());
        List<T> list = query.list();
        return list;
    }

    public <T> void save(T t) {
        sessionFactory.getCurrentSession().save(t);
    }

    public <T> void update(T t) {
        sessionFactory.getCurrentSession().update(t);
    }

    public <T> void delete(T t) {
        sessionFactory.getCurrentSession().delete(t);
    }
}

但是当我尝试像这样用UserDao拉取数据时：

public List<UserEntity> getAll() {
    List<UserEntity> list = UserDao.findAll();
}

Eclipse IDE for line List<UserEntity> list = UserDao.findAll();给出错误:对于类型UserDao，方法findAll()定义不足。

Answer 1

这是我的实现：

GenericDao：

@Repository
public class GenericDao<T extends DbObject> {

    @Autowired
    private SessionFactory sessionFactory;

    private Class<T> getParameterizedClass() {
        return (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
    }

    public T findById(final Serializable id) {
        return (T) getCurrentSession().get(getParameterizedClass(), id.toString());
    }

    public void persist(final T object) {
        getCurrentSession().persist(object);
    }

    public void saveOrUpdate(final T object) {
        getCurrentSession().saveOrUpdate(object);
    }

    public void delete(final T object) {
        getCurrentSession().delete(object);
    }

    public T merge(final T object) {
        return (T) getCurrentSession().merge(object);
    }

}

UserDao：

public class UserDao extends GenericDao<User> {

}

实体：

@Entity
@Table(name = "...")    
public class User extends DbObject {
}