A brief analysis of Hibernate mapping (II.)--Relational mapping (3)

Bidirectional one-to-one correlation mapping

As with one-way mapping, bidirectional mappings can still be implemented in two ways: 1, primary Key Association, 2, unique foreign Key Association

1. Primary Key Association

The mapped relational model is the same as one-way:

The difference between a mapping file and a one-way is that you need to add a <one-to-one> tag to the card to indicate that hibernate will load the associated object user on the primary key. <one-to-one> does not affect storage, only affects loading

User.hbm.xml

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2. <? XML version="1.0"?>
4. <! DOCTYPE hibernate-mapping Public
6. "-//hibernate/hibernate Mapping DTD 3.0//en"
8. "Http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
10. <hibernate-mapping package="Com.jialin.hibernate">
14. <class name="User">
16. <ID name="id">
18. <!--use foreign policy to get the primary key of the associated object--
20. <generator class="foreign">
22. <!--property represents the object to associate--
24. <param name="property">card</param>
26. </Generator>
28. </ID>
30. <property name="name" />
34. <one-to-one name="card" />
36. </class>
40. </hibernate-mapping>

Card.hbm.xml

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2. <? XML version="1.0"?>
4. <! DOCTYPE hibernate-mapping Public
6. "-//hibernate/hibernate Mapping DTD 3.0//en"
8. "Http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
10. <hibernate-mapping package="Com.jialin.hibernate">
14. <class name="Card">
16. <ID name="id">
18. <generator class="native" />
20. </ID>
22. <property name="Cardno" />
24. <!--<one-to-one> does not affect storage, only affects load-
26. <one-to-one name="person" />
30. </class>
34. </hibernate-mapping>

2. Unique FOREIGN Key Association

The mapped relational model is the same as one-way:

Map file:

User.hbm.xml

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2. <? XML version="1.0"?>
4. <! DOCTYPE hibernate-mapping Public
6. "-//hibernate/hibernate Mapping DTD 3.0//en"
8. "Http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
10. <hibernate-mapping package="Com.jialin.hibernate">
14. <class name="person">
16. <ID name="id">
18. <generator class="native" />
20. </ID>
22. <property name="name" />
24. <many-to-one name="card" unique="true"></many-to-one>
26. </class>
30. </hibernate-mapping>

Card.hbm.xml

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2. <? XML version="1.0"?>
4. <! DOCTYPE hibernate-mapping Public
6. "-//hibernate/hibernate Mapping DTD 3.0//en"
8. "Http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
10. <hibernate-mapping package="Com.jialin.hibernate">
14. <class name="Card">
16. <ID name="id">
18. <generator class="native" />
20. </ID>
22. <property name="Cardno" />
24. <!--must specify <one-to-one>
26. The Property-ref attribute in the label is the name of the relationship field-->
28. <one-to-one name="person" property-ref="card"/>

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1. </class>
3. Lt;/hibernate-mapping>

A brief analysis of Hibernate mapping (II.)--Relational mapping (3)