总结：对于web应用来说，查询是多的，更新和删除相对很少，采用code之后能够有效的方便查询，由于code是唯一索引，速度也不会很差，能满足大多数情况下的应用。

 

Hibernate 代码

/**
 *
 * 功能：模版的类别,树型结构
 *
 */
public class TemplateCategoryEntity extends HibernateEntity {

    public static final int CODE_LENGTH = 5;

    private String          name;              //名称，比如杯子，衣服

    private String          parentId;

    private String          code;

    private int             weight      = 100; //排序的权值

}

 

/**
 *
 * 功能：
 *
 */
public class TemplateCategoryEntityDAO extends HibernateDAO {
    public HibernateEntity getEntity() {
        return new TemplateCategoryEntity();
    }

   
public String getQueryString() {
        return "from TemplateCategoryEntity entity";
    }

   
    /**
     * 继承原有方法
     */
    public void insert(IEntity entity) throws DAOException {
        final TemplateCategoryEntity category = (TemplateCategoryEntity) entity;

        getHibernateTemplate().execute(new HibernateCallback() {

            public Object doInHibernate(Session session)
                    throws HibernateException, SQLException {
                //保存当前节点
                session.save(category);
                if ("0".equals(category.getParentId())) {
                    category.setCode(ConvertUtil.toFixString(category.getId(),
                            TemplateCategoryEntity.CODE_LENGTH));
                    session.update(category);// 更新对象
                } else {
                    // 重新计算code
                    TemplateCategoryEntity parent = (TemplateCategoryEntity) session.load(
                            TemplateCategoryEntity.class, category
                                    .getParentId()); // 加载父节点
                    category.setCode(parent.getCode()
                            + "|"
                            + ConvertUtil.toFixString(category.getId(),
                                    TemplateCategoryEntity.CODE_LENGTH));
                    session.update(category);// 更新对象
                }
                return category;
            }

        });
    }

    public void update(IEntity generic) throws DAOException {
        final TemplateCategoryEntity entity = (TemplateCategoryEntity) generic;
        getHibernateTemplate().execute(new HibernateCallback() {
            public Object doInHibernate(Session session)
                    throws HibernateException, SQLException {
                //-----------------------------------------------
                if (entity.getId() == entity.getParentId()) {
                    throw new DAOException("id 和 parentId 不能一样");
                }
                //检查是否存在圈

                if ("0".equals(entity.getParentId())) {
                    entity.setCode(ConvertUtil.toFixString(entity.getId(),
                            TemplateCategoryEntity.CODE_LENGTH));
                    session.update(entity);// 更新对象
                } else {
                    // 重新计算code
                    TemplateCategoryEntity parent = (TemplateCategoryEntity) session
                            .load(TemplateCategoryEntity.class, entity
                                    .getParentId()); // 加载父节点
                    entity.setCode(parent.getCode()
                            + "|"
                            + ConvertUtil.toFixString(entity.getId(),
                                    TemplateCategoryEntity.CODE_LENGTH));
                    session.update(entity);// 更新对象
                }
                // 更新子树里的所有节点
                // 如果是把某个节点置为无效，则需要将子树都设置为无效，反之依然
                log.debug("current code=" + entity.getCode());
                updateChildrenCode(session, entity.getId(), entity.getCode(),
                        entity.isValidTag());

                // ---------------------------------------------- 

                return entity;
            }

        });
    }

    /**
     * 递归更新子树
     *
     * @param session
     * @param id
     * @param code
     * @throws DAOException
     */
    private void updateChildrenCode(Session session, String id, String code,
            boolean validTag) throws DAOException {
        String CHILDREN_SQL = "from TemplateCategoryEntity entity where entity.parentId=:id";
        Query query = session.createQuery(CHILDREN_SQL);
        query.setString("id", id);
        List list = query.list();
        for (int i = 0; i < list.size(); i++) {
            TemplateCategoryEntity child = (TemplateCategoryEntity) list.get(i);

            child.setCode(code
                    + "|"
                    + ConvertUtil.toFixString(child.getId(),
                            TemplateCategoryEntity.CODE_LENGTH));
            child.setValidTag(validTag);
            session.update(child);
            updateChildrenCode(session, child.getId(), child.getCode(), child
                    .isValidTag());
        }
    }

    public void delete(IEntity generic) throws DAOException {
        final TemplateCategoryEntity entity = (TemplateCategoryEntity) generic;
        getHibernateTemplate().execute(new HibernateCallback() {
            public Object doInHibernate(Session session)
                    throws HibernateException, SQLException {
                //-----------------------------------------------
                TemplateCategoryEntity category = (TemplateCategoryEntity) entity;
                ArrayList ids = new ArrayList();
                ids.add(category.getId());
                listAllChildrenIds(session, ids, category.getId());
                log.debug("delete TemplateCategoryEntity ids=" + ids);
                String DELETE = "delete from TemplateCategoryEntity where id in (:ids)";
                Query query = session.createQuery(DELETE);
                query.setParameterList("ids", ids);
                query.executeUpdate();
                // ---------------------------------------------- 
                return entity;
            }

        });
    }

    /**
     * 递归查找孩子
     *
     * @param session
     * @param list
     * @param id
     */
    private void listAllChildrenIds(Session session, List list, String id) {
        String CHILDREN_SQL = "select entity.id from TemplateCategoryEntity entity where entity.parentId=:id";
        Query query = session.createQuery(CHILDREN_SQL);
        query.setString("id", id);
        List children = query.list();
        for (int i = 0; children != null && i < children.size(); i++) {
            String child = ((String) children.get(i));
            log.debug("found children:" + child);
            list.add(child);
            listAllChildrenIds(session, list, child);
        }
    }
}