package anni.core.web.json;

import java.util.List;

import anni.core.dao.HibernateEntityDao;


/**
 * 對(duì)tree進(jìn)行dao操作的基類.
 *
 * @author Lingo
 * @since 2007-09-15
 * @param <T> TreeNode
 */
public class LongTreeHibernateDao<T extends TreeNode<T>>
    extends HibernateEntityDao<T> {
    /**
     * 如果數(shù)據(jù)庫(kù)中不存在指定name的記錄，就將此條記錄插入數(shù)據(jù)庫(kù)，并返回對(duì)應(yīng)的實(shí)體類.
     * 如果數(shù)據(jù)庫(kù)中已經(jīng)存在指定name的記錄，就返回對(duì)應(yīng)的實(shí)體類
     *
     * @param name 數(shù)據(jù)字典的name
     * @return T 返回對(duì)應(yīng)的實(shí)體類
     */
    public T createOrGet(String name) {
        // 輸入的名稱不應(yīng)該為空.
        if ((name == null) || "".equals(name.trim())) {
            return null;
        }

        String beanName = name.trim();

        List<T> list = findBy("name", beanName);

        // 如果找到記錄，應(yīng)該是只有一項(xiàng)目，就返回這條記錄的實(shí)體類
        if (list.size() > 0) {
            return list.get(0);
        } else {
            try {
                // 如果沒(méi)找到記錄，需要把這個(gè)數(shù)據(jù)字典保存進(jìn)數(shù)據(jù)庫(kù)
                T namedEntityBean = (T) getEntityClass().newInstance();
                namedEntityBean.setName(beanName);
                save(namedEntityBean);

                return namedEntityBean;
            } catch (InstantiationException ex) {
                // 如果T是抽象類，調(diào)用getEntityClass().newInstance()就會(huì)拋這個(gè)異常
                System.err.println(ex);
            } catch (IllegalAccessException ex) {
                // 沒(méi)有訪問(wèn)權(quán)限的異常，現(xiàn)在還沒(méi)想到達(dá)成的方法
                System.err.println(ex);
            }

            return null;
        }
    }

    /**
     * 讀取頂端的隊(duì)列.
     *
     * @return List.
     */
    public List<T> loadTops() {
        return find("from " + getEntityClass().getName()
            + " where parent is null");
    }

    /**
     * 讀取頂級(jí)樹(shù)節(jié)點(diǎn).
     *
     * @param columnName 列名
     * @param sort asc/desc
     * @return List
     */
    public List<T> loadTops(String columnName, String sort) {
        return find("from " + getEntityClass().getName()
            + " where parent is null order by " + columnName + " " + sort);
    }
}