Hibernate的单项关联和双项关联


Hiberante 如何建立一对多的双向关联，和单向关联，我用的是Myeclipse自动生成的，好像都是双向的！！ 
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
    <class name="com.yuan.hi.Son" table="son" catalog="joynet">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="increment" />
        </id>
        <many-to-one name="father" class="com.yuan.hi.Father" fetch="select">
            <column name="fatherId" />
        </many-to-one>
        <property name="sonname" type="java.lang.String">
            <column name="sonname" length="20" />
        </property>
        <property name="sonage" type="java.lang.Integer">
            <column name="sonage" />
        </property>
    </class>
</hibernate-mapping>
 ----------------------------------------<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
    <class name="com.yuan.hi.Father" table="father" catalog="joynet">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="increment" />
        </id>
        <property name="fathename" type="java.lang.String">
            <column name="fathename" length="20" />
        </property>
        <set name="sons" inverse="true">
            <key>
                <column name="fatherId" />
            </key>
            <one-to-many class="com.yuan.hi.Son" />
        < t>
    </class>
</hibernate-mapping> 这两个表本身是单向的关联