Hibernate工具类模版

import java.io.Serializable;import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import org.hibernate.service.ServiceRegistry;import org.hibernate.service.ServiceRegistryBuilder;public final class HibernateUtil {private HibernateUtil(){}private static SessionFactory sessionFactory;//利用静态代码块来获得数据库的连接static{Configuration cfg = new Configuration();cfg.configure();ServiceRegistry  sr = new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();  sessionFactory = cfg.buildSessionFactory(sr);}//返回创建的SessionFactory对象public static SessionFactory getSessionFactory() {return sessionFactory;}//返回Session对象public static Session getSession(){return sessionFactory.openSession();}//向数据库增加一条记录public static void addUser(Object entity){Session s = null;Transaction tx = null;try{s = HibernateUtil.getSession();tx=s.beginTransaction();s.save(entity);tx.commit();}catch(HibernateException e){if(tx != null){tx.rollback();}throw e;}finally{if(s!=null){s.close();}}}//更新数据库中的一条记录public static void update(Object entity){Session s = null;Transaction tx = null;try{s = HibernateUtil.getSession();tx=s.beginTransaction();s.update(entity);tx.commit();}catch(HibernateException e){if(tx != null){tx.rollback();}throw e;}finally{if(s!=null){s.close();}}}//删除数据库中的一条记录public static void delete(Object entity){Session s = null;Transaction tx = null;try{s = HibernateUtil.getSession();tx=s.beginTransaction();s.delete(entity);tx.commit();}catch(HibernateException e){if(tx != null){tx.rollback();}throw e;}finally{if(s!=null){s.close();}}}//根据记录ID在数据库中查询一条记录public static Object getById(Class<?> clazz, Serializable id){Session s = null;Transaction tx = null;try{s = HibernateUtil.getSession();tx=s.beginTransaction();Object obj = s.get(clazz, id);tx.commit();return obj;}catch(HibernateException e){if(tx != null){tx.rollback();}throw e;}finally{if(s!=null){s.close();}}}}