hibernate - 何时在 hibernate 中使用 property-ref 属性

Question

我已经完成了示例程序。我使用了 property-ref 属性。即使我不使用它仍然可以工作。请让我知道property-ref属性在这个程序中的实际用法是什么。

 <hibernate-mapping package="com.hibernate.onetone">
 <class name="Book" table="BOOK">
    <id name="id" column="BOOK_ID">
        <generator class="native" />
    </id>
    <property name="title" type="string" column="TITLE" />
    <property name="description" type="string" column="DESCRIPTION" />
    <property name="publishedDate" type="date" column="PUBLISHED" />

    <many-to-one name="author" class="com.hibernate.onetone.Author"
        column="author_id" unique="true" not-null="true"
        cascade="all" />             
   </class>
  </hibernate-mapping>

  <hibernate-mapping package="com.hibernate.onetone">
  <class name="Author" table="AUTHOR">
    <id name="id" column="AUTHOR_ID">
        <generator class="native"/>
    </id>
    <property name="name" column="NAME" />
    <property name="email" column="EMAIL" />  

   <!--  <property name="serialNumber" column="SerialNumber" /> -->
    <one-to-one name="book" class="Book" property-ref="author"
   constrained="true" cascade="all"/>    
   </class> 
  </hibernate-mapping>

   public class Book {
   private long id;
   private String title;
   private String description;
   private Date publishedDate;
   private Author author;       
   }
  public class Author {
  private long id;
  private String name;
  private String email;
  private Book book;     {
  }

Answer 1

property-ref 属性用于建立双向关联并指定关联的哪一方是关系的所有者。在生成的查询中，仅当关系的所有者更新而不是另一方更新时，才会导致外键更新。

如文档中所示

property-ref (optional): the name of a property of the associated class that is joined to this foreign key. If not specified, the primary key of the associated class is used.

另请查看下面的链接以获取更多信息

http://www.allappforum.com/hibernate/hibernate_o_r_mapping_one_to_one_element.htm

http://www.allappforum.com/hibernate/hibernate_o_r_mapping_many_to_one_element.htm

如果您还可以为您提供映射和执行代码，以便我可以使解释更清楚，那就太好了:)