catalogdao.java

网上购物系统struts+spring+hibernate实现

package com.sdi0708.bdifn.bookstore.dao.impl;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;

import com.sdi0708.bdifn.bookstore.dao.ICatalogDao;
import com.sdi0708.bdifn.bookstore.domain.Catalog;

public class CatalogDao extends BaseDao implements ICatalogDao {
	/**
	 * 因为类别不常改变,把它放到内存中,以空间换时间
	 */
	private List<Catalog> catalogs = null;  
	
	/**
	 * 增加一个类别,如果进行了此操作,清空缓存的集合信息
	 */
	public void addCatalog(Catalog catalog,Long parentId) {
		
		Session session = openSession();
		Catalog temp = catalog;
		//获取下一个主键值.自定义算法实现
		temp.setId(getPK(parentId));
		session.save(catalog);
		//可以考虑用spring的aop实现,看时间允许与否
		clearCatalog();
	}

	public void deleteById(Long id) {
		Session session = openSession();
		String hql = "";
		Query query = null;
		if(id % 100 == 0) {
			//如果是顶层的类别,根结点的话的,要把子结点也要删除
			Long hid = id / 100; //取得高位,
			Long cid = hid * 100 + 99; //xx00 到 xx99都删除
			
			hql = "delete from Catalog c  where c.id between ? and ? ";
			query = session.createQuery(hql);
			query.setLong(0, id);
			query.setLong(1, cid);
		} else {
			//如果是叶子节点,可以直接删除.
			hql = "delete from Catalog c where c.id = ?";
			query = session.createQuery(hql);
			query.setLong(0, id);
		}

		query.executeUpdate();
		clearCatalog();
	}

	@SuppressWarnings("unchecked")
	public List<Catalog> findAllCatalogs() {
		if(catalogs == null) {
			synchronized(this) {
				Session session = openSession();
				String hql = "from Catalog c order by c.id";
				Query query = session.createQuery(hql);
				catalogs = query.list();
			}
		}
		return catalogs;
	}

	public Catalog findById(Long id) {
		Catalog catalog = null;
		if(catalogs != null) {
			//先从列表中找
			for(int i = 0 ; i < catalogs.size() ; i ++) {
				Catalog c = catalogs.get(i);
				if(c.getId().equals(id)) {
					catalog = c;
				}
			}
		} else {
			Session session = openSession();
			catalog = (Catalog) session.get(Catalog.class, id);
		}
		return catalog;
	}

	public void modifyCatalod(Catalog catalog) {
		Session session = openSession();
		session.update(catalog);
		clearCatalog();
	}

	public void clearCatalog() {
		//如果发生了任何的改变,则把catalogs置空
		if(catalogs != null && !catalogs.isEmpty())
		catalogs.clear();
		catalogs = null;
	}
	//为四位数
	@SuppressWarnings("unchecked")
	public Long getPK(Long parent) {
		Session session = openSession();
		Long key = null;
		Long h = parent;
		
		String hql = "select max(id) from Catalog";
		Query q = session.createQuery(hql);
		List result = q.list();
		
		//表示增加顶层类别
		if(h == null){
			if(result != null && result.size() == 1) {
				h = (Long) result.get(0)/ 100 + 1;
			}
			//如果是没有记录,从10起.下一个是11下下一个是12
			else h = 10L;
			//它是需层类别,则后两个为零
			key = h * 100 ;
		} else {
			//把后两位数去掉
			key = (h /100) * 100 + (Long) result.get(0) % 100 + 1;
		}
		return key;
	}
	/**
	 * 取得所有的顶层类别
	 */
	public List<Catalog> findParentCatalogs() {
		List<Catalog> catas = new ArrayList<Catalog>();
		List<Catalog> cs =  findAllCatalogs();
		for(int i = 0 ; i < cs.size() ; i ++) {
			Catalog c = cs.get(i);
			if(c.getId() % 100 == 0) {
				//如果第二位ID位是00的话表明是顶层父类别
				catas.add(c);
			}
		}
		return catas;
	}

	public List<Catalog> findLeafCatalogs(Long parentId) {
		List<Catalog> catas = new ArrayList<Catalog>();
		List<Catalog> cs =  findAllCatalogs();
		for(int i = 0 ; i < cs.size() ; i ++) {
			Catalog c = cs.get(i);
			Long tempId = (c.getId() / 100) * 100 ;
			//不把根结点包含进来
			if(tempId.equals(parentId) && !c.getId().equals(parentId) ) {
				catas.add(c);
			}
		}
		return catas;
	}
	

}