Hibernate教程之二：实例讲解

妖狐艹你老母 2022-05-29 05:05 224阅读 0赞

## 一、创建Hibernate 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>
            
            <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
            <property name="hibernate.connection.password">gcki_test</property>
            <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.4.9:1521:orcl</property>
            <property name="hibernate.connection.username">gcki_test</property>
    
    
            
            <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
            
            <property name="show_sql">true</property>
            
            <property name="format_sql">true</property>
    
            
            <property name="hbm2ddl.auto">update</property>
    
            
            <property name="connection.isolation">2</property>
    
    
            
            <mapping resource="com/yang/model/User.hbm.xml"/>
    
    
        </session-factory>
    </hibernate-configuration>

## 二、创建持久化类：将数据库表映射成的一个对象 ##

package com.yang.model;
    
    public class User { 
    
        private Integer id;
        private String name;
        private String telPhone;
        public Integer getId() {
            return id;
        }
        public void setId(Integer id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getTelPhone() {
            return telPhone;
        }
        public void setTelPhone(String telPhone) {
            this.telPhone = telPhone;
        }
        @Override
        public String toString() {
            return "User [id=" + id + ", name=" + name + ", telPhone=" + telPhone + "]";
        }
    }

## 三、创建对象-关系映射文件：声明数据库表和持久化类之间的关系 ##

<?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.yang.model.User" table="RE_HIBERNATE_USER">
            <id name="id" type="java.lang.Integer">
                <column name="ID" />
                
                <generator class="native" />
            </id>
    
    
            <property name="name" type="java.lang.String">
                <column name="NAME" />
            </property>
            <property name="telPhone" type="java.lang.String">
                <column name="TELPHONE" />
            </property>
        </class>
    </hibernate-mapping>

## 四、通过 Hibernate API 编写访问数据库的代码 ##

package Test;
    
    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;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.yang.model.User;
    
    public class StanderTest { 
    
        private SessionFactory  sessionFactory;
        private Configuration configuration;
        private Session session;
        private Transaction transaction;
    
        @Before
        public void init(){
            //自动加载classPath路径下，名为“hibernate.cfg.xml”文件，封装连接数据库的基本信息
            configuration=new Configuration().configure();
            //将连接数据库的信息向ServiceRegistry对象注册
            ServiceRegistry serviceRegistry=new ServiceRegistryBuilder()
                                                .applySettings(configuration.getProperties())
                                                .buildServiceRegistry();
            //sessionFactory的创建相当耗费资源，在生产中将这个变量设置为静态
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);    
            //创建session对象
            session = sessionFactory.openSession();
            //开启事务：不开启事务将没办法执行操作
            transaction = session.beginTransaction();
        }
    
        @After
        public void destory(){
            /* * 1、transaction在调用commit时会先调用session的flush方法，将session对象的状态（就是这个对象的各种属性值） * 与数据库对应的记录保持一致 * 2、本质上就是执行了一条sql语句（session.flush） * 3、最后提交事务，才是数据库记录的最终改变 * */
            transaction.commit();
            session.close();
            sessionFactory.close();
        }
    
    
        @Test
        public void testSave(){     
            User user=new User();
            user.setName("miemie");
            user.setTelPhone("258369");
            session.save(user);     
    
        }
    
    }