java之hibernate之基于主键的单向一对一关联映射

这篇讲 基于主键的单向一对一关联映射

1.依然考察人和身份证的一对一关系，如果采用主键关联，那么其表结构应该为：

2.类结构

Person.java

public class Person implements Serializable{
    private String id;
    private String name;
    private IdCard idCard;
    public Person() {
    }
    public Person(String name) {
        super();
        this.name = name;
    }

    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public IdCard getIdCard() {
        return idCard;
    }
    public void setIdCard(IdCard idCard) {
        this.idCard = idCard;
    }
}

IdCard.java

public class IdCard implements Serializable{
    private String id;
    private String address;
    public IdCard() {
    }
    
    public IdCard(String id, String address) {
        super();
        this.id = id;
        this.address = address;
    }

    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    
}

3. 映射文件

Person.hbm.xml

<hibernate-mapping package="cn.sxt.pojo">
    <class name="Person" table="t_person">
        <id name="id">
            <!-- 表示主键是引用的主表的外键来充当 -->
            <generator class="foreign">
                 <param name="property">idCard</param>
            </generator>
        </id>
        <property name="name"/>
        <!-- 基于主键的单向关联  constrained表示外键约束 -->
        <one-to-one name="idCard" constrained="true"/>
    </class>
</hibernate-mapping>

IdCard.hbm.xml

<hibernate-mapping package="cn.sxt.pojo">
    <class name="IdCard" table="t_idCard">
        <id name="id">
            <generator class="assigned"></generator>
        </id>
        <property name="address"/>
    </class>
</hibernate-mapping>

4.测试

public class HibernateTest {
    /**
     * 生成数据库表的工具方法
     * */
    @Test
    public void testCreateDB(){
        Configuration cfg = new Configuration().configure();
        SchemaExport se = new SchemaExport(cfg);
        //第一个参数  是否打印sql脚本
        //第二个参数 是否将脚本导出到数据库中执行
        se.create(true, true);
    }
    /**
     * 初始化表数据
     */
    @Test
    public void testInit(){
        Session session = null;
        Transaction tx = null;
        try {
            session = HibernateUtil.getSession();
            tx = session.beginTransaction();
            IdCard card1 = new IdCard("110086", "湖北武当");
            IdCard card2 = new IdCard("110087", "光明顶");
            Person p1 = new Person("张三疯");
            p1.setIdCard(card1);
            Person p2 = new Person("殷素素");
            p2.setIdCard(card2);
            session.save(card1);
            session.save(card2);
            session.save(p1);
            session.save(p2);
            tx.commit();
            
        } catch (Exception e) {
            if(tx!=null)
                tx.rollback();
        }finally {
            HibernateUtil.close();
        }
    }
    /**
     */
    @Test
    public void testGetData(){
        Session session = HibernateUtil.getSession();
        Person p1 = (Person)session.get(Person.class, "110086");
        System.out.println(p1.getName()+"----"+p1.getIdCard().getId()+"----"+p1.getIdCard().getAddress());
        HibernateUtil.close();
    }
}