hibernate 无法生成中间表，怎么办？

Question

现在有三个hibernate的xml文件：Role.hbm.xml,User.hbm.xml,SystemPrivilege.hbm.xml。
能够在数据库中创建4个表：itcast_role，itcast_user，itcast_systemprivilege，itcast_user_role。
但是无法创建itcast_role_systemPrivileges表，不知道什么原因？三个配置文件如下：Role.hbm.xml：<hibernate-mapping package="cn.itcast.bbs.domain">
    <class name="Role" table="itcast_role">
        <cache usage="read-write" />        <id name="id" column="id_">
            <generator class="uuid" />
        </id>
        <property name="name" column="name_" length="64" />
        <property name="description" column="description_" length="255" />
        <property name="defaultForNewUser" column="defaultForNewUser_" />        <!-- order-by="1"只是为了用 LinkedHashSet 存放结果，就可以有一定的顺序了 -->
        <set name="systemPrivileges" table="itcast_role_systemPrivileges" lazy="false" order-by="1">
            <cache usage="read-write"/>
            <key column="roleId_"></key>
            <many-to-many class="SystemPrivilege" column="systemPrivilegeId_" />
        </set>
    </class>
</hibernate-mapping>SystemPrivilege.hbm.xml:
<hibernate-mapping package="cn.itcast.bbs.domain">
    <class name="SystemPrivilege" table="itcast_systemprivilege">
        <cache usage="read-only"/>
        <id name="id" column="id_">
            <generator class="uuid" />
        </id>
        <property name="name" column="name_" />
        <property name="action" column="action_" length="64" />
        <property name="resource" column="resource_" length="64" />
    </class>
</hibernate-mapping>

Answer 1

User.hbm.xml：
<hibernate-mapping package="cn.itcast.bbs.domain">
<class name="User" table="itcast_user">
<cache usage="read-write"/> <id name="id" column="id_" length="45">
<generator class="uuid" />
</id>
<property name="loginName" column="loginName_" length="128" />
<property name="password" column="password_" length="128" />
<property name="email" column="email_" length="128" /> <property name="nickname" column="nickname_" length="128" />
<property name="gender" column="gender_" type="genderType" length="16" />
<property name="avatar" column="avatar_" length="204800" />
<property name="signature" column="signature_" length="255" /> <property name="registrationTime" column="registrationTime_" type="timestamp" />
<property name="lastVisitTime" column="lastVisitTime_" type="timestamp" />
<property name="lastVisitIpAddr" column="lastVisitIpAddr_" length="15" /> <property name="topicCount" column="topicCount_" />
<property name="articleCount" column="articleCount_" /> <property name="locked" column="locked_" />
<property name="autoLoginAuthKey" column="autoLoginAuthKey_" length="128" /> <!-- <property name="activationKey" column="activationKey_" length="45" /> -->
<set name="roles" table="itcast_user_role" lazy="false">
<cache usage="read-write"/>
<key column="userId_"></key>
<many-to-many class="Role" column="roleId_"/>
</set>
</class>
</hibernate-mapping>

Answer 2

在你的Ｈｉｂｅｒｎａｔｅ．ｃｆｇ．ｘｍｌ中加入
<property name="hbm2ddl.auto">update</property>

Answer 3

已经有，不用再加。这个表itcast_user_role是可以生成的，但是itcast_role_systemPrivileges为什么无法生成呢？

Answer 4

itcast_role_systemPrivileges没有生成，看看有没有对象的关联关系。
没有就不能生成

Answer 5

<set name="systemPrivileges" table="itcast_role_systemPrivileges" lazy="false" order-by="1">
            <cache usage="read-write"/>
            <key column="roleId_"></key>
            <many-to-many class="SystemPrivilege" column="systemPrivilegeId_" />
        </set>这不是吗？

Answer 6

在Role.hbm.xml：
中，
将<id name="id" column="id_">改为<id name="id" column="id_" length="45">
就生成了表itcast_role_systemPrivileges这是为什么呢？