Hibernate是一个开源的ORM框架,顾名思义,它的核心思想即ORM(Object Relational Mapping,对象关系映射),可以通过对象来操作数据库中的信息,据说开发者一开始是不太熟悉数据库SQL语句的,这也造就了hibernate的强大之处,它不强求开发者熟悉SQL语句也可以操作数据库,hibernate可以自动生成SQL语句,自动执行。用hibernate可以让开发者完全使用面想对象思维来操作数据库,本文使用hibernate实现了简单的对一个person数据表的基本增删改查操作。
核心配置文件hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 以下四行分别为:数据库驱动类、Drivermanager获取连接的参数URL、用户名、密码 -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://127.0.0.1/web?characterEcoding=utf-8</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<!-- 设置方言,hibernate会根据数据库的类型相应生成SQL语句 -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property> <!-- 控制台显示生成的sql语句,默认为false -->
<property name="show_sql">true</property>
<!-- 映射配置源文件的位置 -->
<mapping resource="demo/pojo/Person.hbm.xml"/>
</session-factory> </hibernate-configuration>
映射文件Person.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<!-- name是实体类全名,table为数据表名 -->
<class name="demo.pojo.Person" table="Person">
<id name="id" column="id">
<!-- 主键生成方式,native是让hibernate自动识别 -->
<generator class="native"></generator>
</id>
<!--
注意点:
0.name值为实体类中属性名,column为数据表中字段名;
1.当实体类中属性名与对应数据表字段名相同时,后面的column可以省略,hibernate会自动匹配,例如下面age ;
2.反之当实体类中属性名与对应数据表字段名不相同时,两项都要写上,例如下面gender和sex
-->
<property name="name" column="name"></property>
<property name="gender" column="sex"></property>
<property name="age"></property>
</class>
</hibernate-mapping>
Session工厂类
package demo.util; import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder; public class HibernateSessionFactory {
private static SessionFactory factory;
private static ThreadLocal<Session> thread = new ThreadLocal<Session>();
private static String path = "hibernate.cfg.xml";
private static Configuration config = new Configuration();
static {
config.configure(path);
ServiceRegistry service = new ServiceRegistryBuilder()//定义一个服务注册机
.applySettings(config.getProperties()).buildServiceRegistry();
factory = config.buildSessionFactory(service);//创建Session工厂类
} public static Session getSession() {
Session session = thread.get();
if(session == null || !session.isOpen()) {
session = factory.openSession();
thread.set(session);
}
return session;
} public static void closeSession() {
Session session = thread.get();
if(session != null && session.isOpen()) {
session.close();
thread.set(null);
}
} }
DAO层封装数据各项操作的方法
package demo.dao; import java.io.Serializable;
import org.hibernate.Session;
import org.hibernate.Transaction;
import demo.pojo.Person;
import demo.util.HibernateSessionFactory; public class PersonDaoImpl {
//增删改查,此处以增为例
public boolean add(Person p) {
Session session = HibernateSessionFactory.getSession();//创建Session
Transaction trans = session.beginTransaction();//开启事务
try {
Serializable id = session.save(p);//添加记录并获取主键值
System.out.println(id+"为获取的主键值");//控制台查看主键值
trans.commit();//提交事务
return true;
} catch (Exception e) {
trans.rollback();//获取异常,则事务回滚
} finally {
HibernateSessionFactory.closeSession();//关闭Session
}
return false;
}
}
测试类TestPerson
package demo.test; import org.junit.Test;
import demo.dao.PersonDaoImpl;
import demo.pojo.Person; public class TestPerson {
@Test
public void testAdd() {
//创建一个人类对象
Person p = new Person();
p.setName("张三");
p.setGender("男");
p.setAge(18);
//创建dao层类对象并调用添加方法
PersonDaoImpl dao = new PersonDaoImpl();
dao.add(p);
}
}
转自:http://www.cnblogs.com/young-z/p/7163645.html