组成关系

在一个员工模型里面需要存入

员工公司所在地址的城市，街道

员工籍贯所在的城市，街道，

此时可以抽取城市，街道变成一个模型即是组成关系

Employee

public class Employee {

  private Long id;

  private String name;

  // 公司的地址

  private Address comAddress;

  // 籍贯所在地

  private Address homeAddress;

Employee.hbm.xml

<class name="Employee" table="t_employee">

        <id name="id">

            <generator class="native" />

        </id>

        <property name="name" />

        <!-- 组成关系:以对象的方式来解决重复的信息 -->

        <!-- 公司所在的地址 -->

        <!-- class必须配置为全类名 -->

        <component name="comAddress" class="Address">

            <!-- property:name必须配置成java的属性，column配置成数据库的字段，而且不能重复 -->

            <property name="city" column="com_city" />

            <property name="street" column="com_street" />

        </component>

        <!-- 籍贯所在的地址 -->

        <component name="homeAddress" class="Address">

            <property name="city" column="home_city" />

            <property name="street" column="home_street" />

        </component>

    </class>

MainTest

public class MainTest {

  Session session = null;

  @Before

  public void save() {

    session = HibernateUtils.INSTANCE.getSession();

    session.beginTransaction();

    Address comAddress = new Address("bj", "st1");

    Address homeAddress = new Address("sh", "st2");

    Employee employee = new Employee("user");

    employee.setComAddress(comAddress);

    employee.setHomeAddress(homeAddress);

    session.save(employee);

  }

  @Test

  public void get() throws Exception {

    Employee employee = (Employee) session.get(Employee.class, 1L);

    System.out.println(employee);

    System.out.println(employee.getComAddress());

    System.out.println(employee.getHomeAddress());

  }

  @After

  public void colse() {

    session.getTransaction().commit();

    session.close();

  }

}

源码地址

https://github.com/je-ge/hibernate

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