Hibernate- 表联系

hibernate.cfg.xml 配置文件：连接数据库

<!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="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_many2one</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">bjpowernode</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.show_sql">true</property>
        
       <!-- 数据库表-->
         <mapping resource="com/bjpowernode/hibernate/User.hbm.xml"/>
         <mapping resource="com/bjpowernode/hibernate/Group.hbm.xml"/>

    </session-factory>
</hibernate-configuration>

many-t-one

Group.hbm.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>
    <class name="com.bjpowernode.hibernate.Group" table="t_group">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="name"/>
    </class>
</hibernate-mapping>

User.hbm.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>
    <class name="com.bjpowernode.hibernate.User" table="t_user">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="name"/>
        <many-to-one name="group" column="groupid" cascade="save-update"/>
    </class>
</hibernate-mapping>

one-to-one

IdCard.hbm.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>
    <class name="com.bjpowernode.hibernate.IdCard" table="t_idCard">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="cardNo"/>
    </class>
</hibernate-mapping>

Person.hbm.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>
    <class name="com.bjpowernode.hibernate.Person" table="t_person">
        <id name="id">
            <!-- 采用foreign生成策略，foreign会取得关联对象的标示 -->
            <generator class="foreign">
                <!-- property 指关联对象 -->
                <param name="property">idCard</param>
            </generator>
        </id>
        <property name="name"/>
        <!--
         one-to-one 指示hibernate如何加载其关联对象，默认根据主键加载，
         也就是拿到关联字段值，根据对端的主键来加载关联对象
         
         constrained="true"表示，当前主键（person的主键）还是一个外键
        参照了对端的主键（IdCard的主键），也就是会生成外键约束语句
         -->
        <one-to-one name="idCard" constrained="true"/>
        
    </class>
</hibernate-mapping>