hibernate 之 关联映射的基于外键的单向一对一映射

Posted 2020-09-12 forever_2h

1. 人和身份证是一个一对一的关系，他们的表结构为：

2. 类结构：IdCard.java :

public class IdCard {
    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;
    }
}

person.java :

public class Person {
    private int id;
    private String name;
    private int age;
    private IdCard idCard;
    public Person() {
    }
    public Person(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }

    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;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public IdCard getIdCard() {
        return idCard;
    }
    public void setIdCard(IdCard idCard) {
        this.idCard = idCard;
    }
    
}

3. 映射文件：IdCard.hbm.xml :

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

Person.hbm.xml :

<hibernate-mapping>
    <class name="cn.wh.vo.Person" table="t_person">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"/>
        <property name="age"/>
        <!-- 配置基于外键的一对一的关联映射
            和多对一映射几乎一致，需要设置unique=true
         -->
        <many-to-one name="idCard" column="idCardId" unique="true"/>
    </class>
</hibernate-mapping>

4. 测试：

public class HibernateTest {
    private Session session=null;
    @Before
    public void setUp(){
        session = HibernateUtil.getSession();
    }
    @After
    public void tearDown(){
        HibernateUtil.close();
    }
    @Test
    public void testCreateDB(){
        Configuration cfg = new Configuration().configure();
        SchemaExport export = new SchemaExport(cfg);
        //第一个参数  是否打印  数据库脚本
        //第二个参数 是否将脚本导入数据库执行
        export.create(true, true);
    }
    @Test
    public void testInit(){
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            IdCard card1 = new IdCard("1101","北京昌平");
            IdCard card2 = new IdCard("1102", "北京海淀");
            Person p1 = new Person("张三",22);
            p1.setIdCard(card1);
            Person p2 = new Person("李四",23);
            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();
        }
    }
    @Test
    public void testGet(){
        Person p1 = (Person)session.get(Person.class, 1);
        System.out.println(p1.getName()+"---"+p1.getAge()+"----"+p1.getIdCard().getAddress());
    }
    
}