一个复杂hibernate映射文件

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >

<hibernate-mapping>

<class
    name="example.Element"
    table="T_ELEMENT"
    dynamic-update="true"
    dynamic-insert="true"
    lazy="false">

    <id
        name="listId"
        type="java.lang.Long"
        column="LIST_ID">
        <generator class="sequence">
            <param name="sequence">S_ELEMENT_ID</param>
        </generator>
    </id>

    <property
        name="name"
        type="java.lang.String"
        column="NAME"
        length="50"/>
    <!--
      Node类是Element类的子类,这是遵循table per subclass的继承映射方法
    -->
    <joined-subclass name="example.Node"
        table="T_NODE" lazy="false">

        <key column="LIST_ID" />
       
      <!--
        Node类的父节点是自身类型
      -->
        <many-to-one
            name="parentNode"<!--映射类中的父节点字段-->
            cascade="none"
            outer-join="false">
           
            <column
                name="PARENT_ID"<!--指向父节点的外键-->
                not-null="false"/>
               
        </many-to-one>

        <!--
          Node类的子节点也是自身类型,
        -->
        <set
            name="childNodes"<!--映射类中的所有子节点字段-->
            cascade="all-delete-orphan"
            inverse="true"
            lazy="true"
            batch-size="10"<!--这个属性可以提高性能,若没有设置,则hibernate一次只会取一条-->
            >
           
            <key column="PARENT_ID"/>
            <one-to-many class="example.Node"/>
           
        </set>
       
    </joined-subclass>

</class>
</hibernate-mapping>