[转]一个泛型Hibernate DAO实现-优快云博客

本文介绍了一个通用的Hibernate DAO实现，支持基本的CRUD操作及分页查询等功能，简化了日常开发中对数据库的操作。

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java 代码

package sgf4web.dao;
import java.io.Serializable;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.hibernate.*;
import org.hibernate.criterion.*;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import sgf4web.dao.support.PaginationSupport;
import sgf4web.util.GenericsUtils;
/** *//**
* 泛型Hibernate DAO类
*
* @author DigitalSonic
*/
@SuppressWarnings("unchecked")
public class HibernateGenericDao<T, ID extends Serializable> extends HibernateDaoSupport ...{
private Class<T> pojoClass;
/** *//**
* 初始化DAO，获取POJO类型
*/
public HibernateGenericDao() ...{
// this.pojoClass = (Class<T>)((ParameterizedType)getClass().getGenericSuperclass()).getActualTypeArguments()[0];
this.pojoClass = GenericsUtils.getSuperClassGenricType(getClass());
}
/** *//**
* 获得该DAO对应的POJO类型
*/
public Class<T> getPojoClass() ...{
return this.pojoClass;
}
/** *//**
* 获得该DAO对应的POJO类型名
*/
public String getPojoClassName() ...{
return getPojoClass().getName();
}
//加载对象
/** *//**
* 加载所有的对象
*/
public List<T> loadAll() ...{
return (List<T>)getHibernateTemplate().loadAll(getPojoClass());
}
/** *//**
* 根据hql查询
*
* @param values 可变参数
*/
public List find(String hql, Object... values) ...{
return getHibernateTemplate().find(hql, values);
}
/** *//**
* 根据条件加载对象
*
* @param criteria Criteria实例
*/
public List<T> findByCriteria(final Criteria criteria) ...{
List list = criteria.list();
return transformResults(list);
}
/** *//**
* 根据条件加载对象
* @param detachedCriteria DetachedCriteria实例
*/
public List<T> findByCriteria(final DetachedCriteria detachedCriteria) ...{
return (List<T>) getHibernateTemplate().execute(new HibernateCallback() ...{
public Object doInHibernate(Session session) throws HibernateException ...{
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
List list = criteria.list();
return transformResults(list);
}
}, true);
}
/** *//**
* 根据给定的实例查找对象
*/
public List<T> findByExample(T instance) ...{
List<T> results = (List<T>)getHibernateTemplate().findByExample(instance);
return results;
}
/** *//**
* 根据ID查找对象
*/
public T findById(ID id) ...{
return (T) getHibernateTemplate().get(getPojoClassName(), id);
}
/** *//**
* 根据某个具体属性进行查找
*/
public List<T> findByProperty(String propertyName, Object value) ...{
String queryString = "from " + getPojoClassName() + " as model where model."
+ propertyName + "= ?";
return (List<T>)getHibernateTemplate().find(queryString, value);
}
//新建、修改、删除
/** *//**
* 新建对象实例化
*/
public ID save(T transientInstance) ...{
return (ID)getHibernateTemplate().save(transientInstance);
}
/** *//**
* 更新已存在的对象
*/
public void update(T transientInstance) ...{
getHibernateTemplate().update(transientInstance);
}
/** *//**
* 删除指定ID的对象
*/
public void delete(ID id) ...{
T instance = findById(id);
if (instance != null)
getHibernateTemplate().delete(instance);
}
/** *//**
* 删除指定对象
*/
public void delete(T persistentInstance) ...{
getHibernateTemplate().delete(persistentInstance);
}
//分页
/** *//**
* 根据Criteria加载分页，指定页大小和起始位置
*/
public PaginationSupport findPageByCriteria(final Criteria criteria, final int pageSize, final int startIndex) ...{
int totalCount = getCountByCriteria(criteria);
criteria.setProjection(null);
List items = criteria.setFirstResult(startIndex).setMaxResults(pageSize).list();
items = transformResults(items);
PaginationSupport ps = new PaginationSupport(items, totalCount, pageSize, startIndex);
return ps;
}
/** *//**
* 根据Criteria加载分页，默认页大小，从第0条开始
*/
public PaginationSupport findPageByCriteria(final Criteria criteria) ...{
return findPageByCriteria(criteria, PaginationSupport.PAGESIZE, 0);
}
/** *//**
* 根据Criteria加载分页，默认页大小，从第startIndex条开始
*/
public PaginationSupport findPageByCriteria(final Criteria criteria, final int startIndex) ...{
return findPageByCriteria(criteria, PaginationSupport.PAGESIZE, startIndex);
}
/** *//**
* 根据Criteria统计总数
*/
public int getCountByCriteria(final Criteria criteria) ...{
Integer count = (Integer) criteria.setProjection(Projections.rowCount()).uniqueResult();
return count.intValue();
}
/** *//**
* 根据DetachedCriteria加载分页，指定页大小和起始位置
*/
public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, final int pageSize, final int startIndex) ...{
return (PaginationSupport) getHibernateTemplate().execute(new HibernateCallback() ...{
public Object doInHibernate(Session session) throws HibernateException ...{
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
int totalCount = ((Integer) criteria.setProjection(Projections.rowCount()).uniqueResult()).intValue();
criteria.setProjection(null);
List items = criteria.setFirstResult(startIndex).setMaxResults(pageSize).list();
items = transformResults(items);
PaginationSupport ps = new PaginationSupport(items, totalCount, pageSize, startIndex);
return ps;
}
}, true);
}
/** *//**
* 根据DetachedCriteria加载分页，默认页大小，从第0条开始
*/
public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria) ...{
return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, 0);
}
/** *//**
* 根据DetachedCriteria加载分页，默认页大小，从第startIndex条开始
*/
public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, final int startIndex) ...{
return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, startIndex);
}
/** *//**
* 根据DetachedCriteria统计总数
*/
public int getCountByCriteria(final DetachedCriteria detachedCriteria) ...{
Integer count = (Integer) getHibernateTemplate().execute(new HibernateCallback() ...{
public Object doInHibernate(Session session) throws HibernateException ...{
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
return criteria.setProjection(Projections.rowCount()).uniqueResult();
}
}, true);
return count.intValue();
}
/** *//**
* 根据hql加载分页，指定页大小和起始位置
*/
public PaginationSupport findPageByQuery(final String hql, final int pageSize, final int startIndex, Object...values) ...{
int totalCount = getCountByQuery(hql, values);
if (totalCount < 1)
return new PaginationSupport(new ArrayList(0), 0);
Query query = createQuery(hql, values);
List items = query.setFirstResult(startIndex).setMaxResults(pageSize).list();
PaginationSupport ps = new PaginationSupport(items, totalCount, pageSize, startIndex);
return ps;
}
/** *//**
* 根据hql加载分页，默认页大小，从第0条开始
*/
public PaginationSupport findPageByQuery(final String hql, Object...values) ...{
return findPageByQuery(hql, PaginationSupport.PAGESIZE, 0, values);
}
/** *//**
* 根据hql加载分页，默认页大小，从第startIndex条开始
*/
public PaginationSupport findPageByQuery(final String hql, final int startIndex, Object...values) ...{
return findPageByQuery(hql, PaginationSupport.PAGESIZE, startIndex, values);
}
/** *//**
* 根据hql统计总数
*/
public int getCountByQuery(final String hql, Object...values) ...{
String countQueryString = " select count (*) " + removeSelect(removeOrders(hql));
List countlist = getHibernateTemplate().find(countQueryString, values);
return (Integer) countlist.get(0);
}
//创建Criteria和Query
/** *//**
* 创建Criteria对象
*
* @param criterions 可变的Restrictions条件列表
*/
public Criteria createCriteria(Criterion...criterions) ...{
Criteria criteria = getSession().createCriteria(getPojoClass());
for (Criterion c : criterions)
criteria.add(c);
return criteria;
}
/** *//**
* 创建Criteria对象，带排序字段与升降序字段
*/
public Criteria createCriteria(String orderBy, boolean isAsc, Criterion...criterions) ...{
Criteria criteria = createCriteria(criterions);
if (isAsc)
criteria.addOrder(Order.asc(orderBy));
else
criteria.addOrder(Order.desc(orderBy));
return criteria;
}
/** *//**
* 方法取自SpringSide.
* 创建Query对象. 对于需要first,max,fetchsize,cache,cacheRegion等诸多设置的函数,可以在返回Query后自行设置.
* 留意可以连续设置,如下：
* <pre>
* dao.getQuery(hql).setMaxResult(100).setCacheable(true).list();
* </pre>
* 调用方式如下：
* <pre>
* dao.createQuery(hql)
* dao.createQuery(hql,arg0);
* dao.createQuery(hql,arg0,arg1);
* dao.createQuery(hql,new Object[arg0,arg1,arg2])
* </pre>
*
* @param values 可变参数.
*/
public Query createQuery(String hql, Object... values) ...{
Query query = getSession().createQuery(hql);
for (int i = 0; i < values.length; i++) ...{
query.setParameter(i, values[i]);
}
return query;
}
/** *//**
* 方法取自SpringSide.
* 去除hql的select子句，未考虑union的情况
*/
private static String removeSelect(String hql) ...{
int beginPos = hql.toLowerCase().indexOf("from");
return hql.substring(beginPos);
}
/** *//**
* 方法取自SpringSide.
* 去除hql的orderby子句
*/
private static String removeOrders(String hql) ...{
Pattern p = Pattern.compile("order\s*by[\w|\W|\s|\S]*", Pattern.CASE_INSENSITIVE);
Matcher m = p.matcher(hql);
StringBuffer sb = new StringBuffer();
while (m.find()) ...{
m.appendReplacement(sb, "");
}
m.appendTail(sb);
return sb.toString();
}
/** *//**
* 将联合查询的结果内容从Map或者Object[]转换为实体类型，如果没有转换必要则直接返回
*/
private List transformResults(List items) ...{
if (items.size() > 0) ...{
if (items.get(0) instanceof Map) ...{
ArrayList list = new ArrayList(items.size());
for (int i = 0; i < items.size(); i++) ...{
Map map = (Map)items.get(i);
list.add(map.get(CriteriaSpecification.ROOT_ALIAS));
}
return list;
} else if (items.get(0) instanceof Object[]) ...{
ArrayList list = new ArrayList(items.size());
int pos = 0;
for (int i = 0; i < ((Object[])items.get(0)).length; i++) ...{
if (((Object[])items.get(0))[i].getClass() == getPojoClass()) ...{
pos = i;
break;
}
}
for (int i = 0; i < items.size(); i++) ...{
list.add(((Object[])items.get(i))[pos]);
}
return list;
} else
return items;
} else
return items;
}
}