hibernate ExportDB 编写及one2one笔记一（主键单项关联）

本人用的是hibernate5.2.10，所以跟视频学习hibernate中ExportDB类的编写出现一些问题：

public class ExportDB {
    public static void main(String[] args) {
        // 默认读取hibernate.cfg.xml文件    
        Configuration cfg = new Configuration().configure();    
        // 生成并输出sql到文件（当前目录）和数据库    
        SchemaExport export = new SchemaExport(cfg);    
        // 创建表结构，第一个true 表示在控制台打印sql语句，第二个true 表示导入sql语句到数据库  
        export.create(true, true);    
    }

}

　　经过查阅，现将该类改为：

public class ExportDB {

    public static void main(String[] args) {

        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
        Metadata metadata = new MetadataSources(serviceRegistry).buildMetadata();
        SchemaExport schemaExport = new SchemaExport();
        schemaExport.create(EnumSet.of(TargetType.DATABASE), metadata);

    }
}

两个实体类，Person和IdCard类，单向关联 Person -->IdCard

Person类

public class Person {
    private int id;
    private String name;
    private IdCard idCard;

    public IdCard getIdCard() {
        return idCard;
    }

    public void setIdCard(IdCard idCard) {
        this.idCard = idCard;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

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 package="com.cnblogs.hibernate_first">
    <class name="Person" table="t_person">
        <id name="id" column="t_id">
        <!-- 采用foreign生成测录，foreign可以取到关联对象的标识 -->
            <generator class="foreign">
            <!-- property 只关联对象 -->
                <param name="property">idCard</param>
            </generator>
        </id>
        <property name="name" column="t_name" length="30"/>
        <!--  constrained="true" 表示当前主键（Pserson的主键）还是一个外键（参照IDCard对端的主键） 也就是会生成外键约束语句
        one-to-one指示hibernate如何加载其关联对象，默认根据主键加载
        也就是拿到关系字段值，根据对端的主键来加载关联对象
        -->
        <one-to-one name="idCard" constrained="true"></one-to-one>
    </class>
</hibernate-mapping>

IdCard类:

public class IdCard {
    private int id;
    private String cardNo;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getCardNo() {
        return cardNo;
    }

    public void setCardNo(String cardNo) {
        this.cardNo = cardNo;
    }

}

IdCard.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 package="com.cnblogs.hibernate_first">
    <class name="IdCard" table="t_idcard">
        <id name="id" column="t_id">
            <generator class="native"></generator>
        </id>
        <property name="cardNo" column="t_cardNo" length="30"/>
    </class>
</hibernate-mapping>

 

测试类：

public class One2OneTest extends TestCase {

    public void testSave1() {
        Session session = null;
        try {
            session = HibernateUtils.getSession();
            session.beginTransaction();
            IdCard idCard = new IdCard();
            idCard.setCardNo("123123123");
            Person person = new Person();
            person.setName("张三");
            // 建立关联
            person.setIdCard(idCard);
            session.save(person);
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        } finally {
            HibernateUtils.closeSession(session);
        }
    }

    public void testLoad1() {
        Session session = null;
        try {
            session = HibernateUtils.getSession();
            session.beginTransaction();
            Person person = session.load(Person.class, 1);
            System.out.println("Person.name = " + person.getName());
            System.out.println("Pserson.cardNo = " + person.getIdCard().getCardNo());
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        } finally {
            HibernateUtils.closeSession(session);
        }
    }
}

testload1（）方法得到的结果就是：

Hibernate: alter table t_person add constraint FKt1wqtq1hcqkcmd4vk2cmhgd1c forei
gn key (t_id) references t_idcard (t_id)
Hibernate: select person0_.t_id as t_id1_1_0_, person0_.t_name as t_name2_1_0_ f
rom t_person person0_ where person0_.t_id=?
Person.name = 张三
Hibernate: select idcard0_.t_id as t_id1_0_0_, idcard0_.t_cardNo as t_cardNo2_0_
0_ from t_idcard idcard0_ where idcard0_.t_id=?
Pserson.cardNo = 123123123