hibernate学习1之基础工具

//根据映射文件生成数据库表

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class ExportDB {

	public static void main(String[] args) {
		
		//读取hibernate.cfg.xml文件
		Configuration cfg = new Configuration().configure();
		
		SchemaExport export = new SchemaExport(cfg);
		
		export.create(true, true);
	}
}

//session工具类

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtils {

	private static SessionFactory factory;
	
	static {
		try {
			Configuration cfg = new Configuration().configure();
			factory = cfg.buildSessionFactory();
		}catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	public static SessionFactory getSessionFactory() {
		return factory;
	}
	
	public static Session getSession() {
		return factory.openSession();
	}
	
	public static void closeSession(Session session) {
		if (session != null) {
			if (session.isOpen()) {
				session.close();
			}
		}
	}
}

hibernate配置文件

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
		<property name="hibernate.connection.url">jdbc:mysql://localhost/hibernate_session</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">bjsxt</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="hibernate.show_sql">true</property>
		
		<mapping resource="com/bjsxt/hibernate/User.hbm.xml"/>
	</session-factory>
</hibernate-configuration>

//实体类

public class User {
	private String id;
	private String name;
	private String password;
	private Date createTime;
	private Date expireTime;
	//setter&getter略
}

//映射文件User.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.bjsxt.hibernate.User">
		<id name="id">
			<generator class="uuid"/>
		</id>
		<property name="name"/>
		<property name="password"/>
		<property name="createTime"/>
		<property name="expireTime"/>
	</class>
</hibernate-mapping>

//测试一下

import java.util.Iterator;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import junit.framework.TestCase;

public class QueryTest extends TestCase {

	public void testQuery() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			Query query = session.createQuery("from User");
			query.setFirstResult(2);//分页
			query.setMaxResults(2);
			List userList = query.list();
			for (Iterator iter=userList.iterator(); iter.hasNext();) {
				User user = (User)iter.next();
				System.out.println(user.getId());
				System.out.println(user.getName());
			}
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}

        public void testSave() {
		Session session = null;
		Transaction tx = null;
		User user = null;
		try {
			session = HibernateUtils.getSession();
			tx = session.beginTransaction();
			
			//Transient（不稳定）状态
			user = new User();
			user.setName("李四");
			user.setPassword("123");
			user.setCreateTime(new Date());
			user.setExpireTime(new Date());
			
			//persistent（持久）状态,当属性发生改变的时候，hibernate会自动和数据库同步
			session.save(user);
			
			user.setName("王五");//数据库里存的是“李四”还是“王五”呢？：）
			
			tx.commit();
		}catch(Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
		
		
	}
}