Hibernate的简单使用

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首先在eclips中下载hibernate插件http://download.jboss.org/jbosstools/neon/stable/updates/

建立hibernate.cfg.xml

hibernate步骤：

建立User类与数据库中的user表对应，形成持久化对象

User.hbm.xml如下

其中id标签对应表中的主键

UserDAO接口

public interface UserDAO {
void save(User user);
User findById(int id);
void delete(User user);
void update(User user);
}

UserDAOImpl实现类

public class UserDAOImpl implements UserDAO{
public void save(User user) {
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();
try {
session.save(user);
tx.commit();
} catch(Exception e) {
e.printStackTrace();
tx.rollback();
} finally {
HibernateUtil.closeSession();
}
}

public User findById(int id) {
User user = null;
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();

try {
user = (User)session.get(User.class, id);
tx.commit();
} catch (Exception e) {
e.printStackTrace();
tx.rollback();
} finally {
HibernateUtil.closeSession();
}
return user;
}

public void delete(User user) {
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();

try {
session.delete(user);
tx.commit();
} catch (Exception e) {
e.printStackTrace();
tx.rollback();
} finally {
HibernateUtil.closeSession();
}
}

public void update(User user) {
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();

try {
session.update(user);
tx.commit();
} catch (Exception e) {
e.printStackTrace();
tx.rollback();
} finally {
HibernateUtil.closeSession();
}
}
}

HibernateUtil辅助类

private static SessionFactory sessionFactory;

private static Configuration configuration = new Configuration();
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
static {
try {
Configuration cfg = new Configuration().configure();
sessionFactory = cfg.buildSessionFactory();
} catch(Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}

public static SessionFactory getSessionFactory() {
return sessionFactory;
}

public static Session getSession() throws HibernateException {
Session session = (Session)threadLocal.get();

if(session == null || !session.isOpen()) {
if(sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession() : null;
threadLocal.set(session);
}
return session;
}

public static void closeSession() throws HibernateException {
Session session = (Session)threadLocal.get();
threadLocal.set(null);
if(session != null) {
session.close();
}
}

public static void rebuildSessionFactory() {
try {
configuration.configure("/hibernate.cfg.xml");
sessionFactory = configuration.buildSessionFactory();
} catch(Exception e) {
System.out.println("Error Creating SessionFactory");
e.printStackTrace();
}
}

public static void shutdown() {
getSessionFactory().close();
}
}

Configuration--SessionFactory---Session---Transaction

测试类如下

@Test
public void testSave() {
UserDAO userdao = new UserDAOImpl();

try {
User u = new User();
u.setId(22);
u.setName("freshbin000");
u.setPassword("tyb");
u.setType("admin");

userdao.save(u);

} catch (Exception e) {
e.printStackTrace();
}
}

经过一天的努力，终于实现了hibernate的第一个例子

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