主键共享方式和外键方式一对一双向关系映射(参考张龙老师的例子)

1.学生类：Student.java

package org.yang.hibernate.model;

public class Student
{
    private String id;
    private String name;
    private IdCard idCard;
    
    public Student(){}

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public IdCard getIdCard() {
        return idCard;
    }

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

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

    public void setIdCard(IdCard idCard) {
        this.idCard = idCard;
    }
}
2.身份证类：IdCard.java

package org.yang.hibernate.model;

public class IdCard
{
    private String id;
    private int number;
    private Student student;
    
    public IdCard(){}

    public String getId() {
        return id;
    }

    public int getNumber() {
        return number;
    }

    public Student getStudent() {
        return student;
    }

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

    public void setNumber(int number) {
        this.number = number;
    }

    public void setStudent(Student student) {
        this.student = student;
    }
}

3.学生类的映射文件：Student.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
    <class name="org.yang.hibernate.model.Student" table="student">
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        <property name="name" column="name" type="string"></property>
        
        <one-to-one name="idCard" class="org.yang.hibernate.model.IdCard" cascade="all" fetch="join">
        </one-to-one>
        
    </class>
</hibernate-mapping>

4.身份证类的映射文件：IdCard.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
    <class name="org.yang.hibernate.model.IdCard" table="idcard">
        <id name="id" column="id">
            <generator class="foreign">
                <!--
                     根据当前类IdCard的哪一个属性的名字来生成.
                     在Student的hbm根据IdCard来生成也是可以的。
                     这根据个人喜好
                 -->
                <param name="property">student</param>
            </generator>
        </id>
        
        <property name="number" column="number" type="integer"></property>
        
        <one-to-one name="student" class="org.yang.hibernate.model.Student"></one-to-one>
        <!--

        外键关联，本质上就是一对多的蜕化形式。在many-to-one元素中增加unique="true"就成了一对一

        当修改成这个样子时，也不要忘记了将<id>元素的主键生成方式也改掉。改为：

　　<id name="id" column="id">

            <generator class="uuid" />

      </id>

        <many-to-one name="student" unique="true" class="org.yang.hibernate.model.Student" column="student_id"/>

        -->

    </class>
</hibernate-mapping>

5.总配置文件：hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >
<hibernate-configuration>
  <session-factory>
        <property name="connection.driver_class">org.postgresql.Driver</property>
        <property name="connection.url">jdbc:postgresql://localhost:5432/hibernate</property>
        <property name="hibernate.connection.username">postgres</property>
        <property name="hibernate.connection.password">yang</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="current_session_context_class">thread</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        
        <mapping resource="IdCard.hbm.xml"/>
        <mapping resource="Student.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

6.生成数据库表的代码文件：CreateTable.java

package org.yang.hibernate;

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class CreateTable
{
    public static void main(String[] args)
    {
        SchemaExport export = new SchemaExport(new Configuration().configure());
        export.create(true, true);
    }
}

7.测试文件：HibernateTest.java

package org.yang.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.yang.hibernate.model.IdCard;
import org.yang.hibernate.model.Student;

public class HibernateTest
{
    private static final SessionFactory sessionFactory;
    static {
        try
        {
            sessionFactory = new Configuration().configure().buildSessionFactory();
        }
        catch(Throwable ex)
        {
            System.err.println("Initial SessionFactory failed " + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    
    public static void main(String[] args)
    {
     
        Student student = new Student();
        student.setName("yangzhiyong");
        
        IdCard idCard = new IdCard();
        idCard.setNumber(987654);
        
        student.setIdCard(idCard);
        idCard.setStudent(student);
        
        Session session = sessionFactory.openSession();
        Transaction tx = null;
        try
        {
            tx = session.beginTransaction();
            session.save(student);
            tx.commit();
        }
        catch (Exception e)
        {
            if (null != tx)
            {
                tx.rollback();
            }
            e.printStackTrace();
        }
        finally
        {
            session.close();
        }
  }
}