1 多對一
第一步 ：建立對象模型
User
-----------------------------
id：int
name：String
group：Group
Group
------------------------------
id:int
name:String
第二步：映射文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="User" table="t_user">
<id name="id" column="id">
<generator class="identity"/>
</id>
<property name="name" column="User_name" unique="true"/>
<many-to-one name="group" column="groupid"/>
</class>
</hibernate-mapping>
2 一對一映射
2.1 主鍵映射
1. 建立對象模型
Person[id-int,name-String]
IdCard[id-int,cardNo-int]
2. 映射文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Person" table="t_person">
<id name="id">
<generator class="foreign">
<param name="property">idCard</param>
</generator>
</id>
<property name="name" column="Person_name" />
<one-to-one name="idCard" constrained="true"/>
</class>
</hibernate-mapping>
2.2 主鍵映射雙向
只需要在IdCard 的XML中添加<one-to-one>標簽指向person，就可以 告訴Hibernate如何加載person，默認按照主鍵加載
2.3 外鍵關聯映射
1. 對象模型
Person[id-int，name-String，idcard-IdCard]
IdCard[id-int，cardNo-int]
2 mapping文件
Xml代碼
Person.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Person" table="t_person">
<id name="id">
<generator class="identity">
</generator>
</id>
<property name="name" column="Person_name" />
<many-to-one name="idCard" unique="true"></many-to- one>
</class>
</hibernate-mapping>
2.4 one-to-one 外鍵雙向mapping
只需要在另一端（IdCard）加入<one-to-one>標簽，但是hibernate默 認按照主鍵加載，所以要告訴hibernate按照指定列來加載
示意：
Xml代碼
Id-card
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="IdCard" table="t_idcard">
<id name="id" column="id">
<generator class="identity"/>
</id>
<property name="cardNo" column="cardno" />
<one-to-one name="person" property-ref="idCard"></one-to- one>
</class>
</hibernate-mapping>
3 一對多映射
1 建立對象模型
Classes[id-int,name-String,student-Set]
Student[id-int,name-String]
2 映射文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Class" table="t_class">
<id name="id">
<generator class="native"/>
</id>
<property name="name" />
<set name="student" >
<key column="classid" />
<one-to-many class="Student"/>
</set>
</class>
</hibernate-mapping>
缺點：若將Student的classid設置為非空，將無法保存。應為不是student這 一端維護關系，所以student不知道是哪個班級，所以需要發出多余的update語 句來更新關系。
（一對多）： 先要session.sava（學生），再sessio.save（班級）
（多對一）： 先要session.sava（班級），再sessio.save（學生）
改進 采用 一對多雙向關聯
Xml代碼
<set name="student" inverse="true">
<set name="student" inverse="true">
這樣的好處是 存入數據讓多的一端進行維護，不需要發出多余的 update.
4 多對多mapping
單向（采用第三方表）
1 對象模型
Role[id-int,name-String]
User[id-int,name-String,role-Set]
2映射文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="User" table="t_user">
<id name="id">
<generator class="native"/>
</id>
<property name="name" />
<set name="role" table="t_user_role">
<key column="userid"></key>
<many-to-many class="Role" column="roleid" />
</set>
</class>
</hibernate-mapping>
雙向：
1 對象模型：
Role[id-int,name-String,user-Set]
User[id-int,name-String,role-Set]
2 mapping文件：
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Role" table="t_role">
<id name="id">
<generator class="native"/>
</id>
<property name="name" />
<set name="user" table="t_user_role">
<key column="userid"></key>
<many-to-many class="User" column="userid" />
</set>
</class>
</hibernate-mapping>
5 繼承mapping
第一類繼承映射
1 對象模型
Animal
private int id
private String name
private Boolean sex
--------------------------------------------------
public class Bird extends Animal
private int height
--------------------------------------------------
public class Pig extends Animal
private int weight
2 mapping 文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Animal" table="t_animal" >
<id name="id" >
<generator class="native"/>
</id>
<discriminator column="type" type="string"></discriminator>
<property name="name"/>
<property name="sex"/>
<subclass name="Pig" discriminator-value="P">
<property name="weight"/>
</subclass>
<subclass name="Bird" discriminator-value="B">
<property name="height"/>
</subclass>
</class>
</hibernate-mapping>
第二類mapping
1 對象模型
2 mapping 文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Animal" table="t_animal" >
<id name="id" >
<generator class="native"/>
</id>
<property name="name"/>
<property name="sex"/>
<joined-subclass name="Pig" table="t_pig">
<key column="pid"/>
<property name="weight"/>
</joined-subclass>
<joined-subclass name="Bird" table="t_bird">
<key column="bid"/>
<property name="height"/>
</joined-subclass>
</class>
</hibernate-mapping>
3 第三類mapping
1對象模型
2 mapping 文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="Animal" table="t_animal" >
<id name="id" >
<generator class="native"/>
</id>
<property name="name"/>
<property name="sex"/>
<union-subclass name="Pig" table="t_pig">
<property name="weight"/>
</union-subclass>
<union-subclass name="Bird" table="t_bird">
<property name="height"/>
</union-subclass>
</class>
</hibernate-mapping>
6 Component 映射
component不是實體，沒有OID。
1 對象模型
public class Employee
private int id
private String name
private Contact contact
-------------------------------------
public class Contact
private String email
private String address
private String zipcode
private String contactTel
-------------------------------------
public class User
private int id
private String name
private Contact contact
2 mapping文件
Xml代碼
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="User" table="t_user" >
<id name="id" >
<generator class="native"/>
</id>
<property name="name"/>
<component name="contact">
<property name="email"></property>
<property name="address"></property>
<property name="zipcode"></property>
<property name="contactTel"></property>
</component>
</class>
</hibernate-mapping>
7 復合主鍵mapping
通常將復合主鍵相關屬性，單獨放到一個類中
這個類必須實現 Serializable接口
這個類必須重寫hashCode（）和equals（）方法
XML
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.nintenyun.hibernate">
<class name="SC" table="t_sc" >
<composite-id name="scpk">
<key-property name="sno"/>
<key-property name="cno"/>
</composite-id>
<property name="sname"></property>
<property name="cname"></property>
</class>
</hibernate-mapping>
