hibernate主键

<hibernate-mapping>
    <class name="com.ActionLog" table="ACTION_LOG">
        <id name="id" type="java.lang.Long">
            <column name="ID" length="32" />
            <generator class="identity">
   </generator>
        </id>
        <property name="adate" type="timestamp">
            <column name="ADATE" length="7" />
        </property>

    </class>
</hibernate-mapping>