[转载]使用hibernate实现树形结构无限级分类
时间: 2023-09-22 15:07:49 浏览: 44
好的,我明白了。关于你的问题,使用 Hibernate 实现树形结构无限级分类,可以采用以下步骤:
1. 定义实体类,包括父子关系、名称等属性,例如:
```
@Entity
@Table(name = "category")
public class Category {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "name")
private String name;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "parent_id")
private Category parent;
@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
private List<Category> children = new ArrayList<>();
// getter and setter methods
}
```
2. 定义 DAO 层接口,包括增删改查、查询某个节点的所有子节点等方法,例如:
```
public interface CategoryDao {
Category save(Category category);
void delete(Category category);
Category findById(Long id);
List<Category> findAll();
List<Category> findByParentId(Long parentId);
List<Category> findAllChildren(Long parentId);
}
```
3. 实现 DAO 层接口,其中 findAllChildren 方法需要使用递归算法查询某个节点的所有子节点,例如:
```
@Repository
public class CategoryDaoImpl implements CategoryDao {
@Autowired
private SessionFactory sessionFactory;
@Override
public Category save(Category category) {
sessionFactory.getCurrentSession().saveOrUpdate(category);
return category;
}
@Override
public void delete(Category category) {
sessionFactory.getCurrentSession().delete(category);
}
@Override
public Category findById(Long id) {
return sessionFactory.getCurrentSession().get(Category.class, id);
}
@Override
public List<Category> findAll() {
return sessionFactory.getCurrentSession().createQuery("from Category", Category.class).getResultList();
}
@Override
public List<Category> findByParentId(Long parentId) {
return sessionFactory.getCurrentSession().createQuery("from Category where parent.id = :parentId", Category.class)
.setParameter("parentId", parentId)
.getResultList();
}
@Override
public List<Category> findAllChildren(Long parentId) {
List<Category> children = findByParentId(parentId);
for (Category child : children) {
List<Category> grandchildren = findAllChildren(child.getId());
child.setChildren(grandchildren);
}
return children;
}
}
```
4. 在业务层或控制层中调用 DAO 层方法,例如:
```
@Service
@Transactional
public class CategoryService {
@Autowired
private CategoryDao categoryDao;
public Category save(Category category) {
return categoryDao.save(category);
}
public void delete(Category category) {
categoryDao.delete(category);
}
public Category findById(Long id) {
return categoryDao.findById(id);
}
public List<Category> findAll() {
return categoryDao.findAll();
}
public List<Category> findAllChildren(Long parentId) {
return categoryDao.findAllChildren(parentId);
}
}
```
以上就是使用 Hibernate 实现树形结构无限级分类的步骤,希望能对你有所帮助。