java – hibernate很多关系级联

我有映射

a.hbm.xml有

<set name="bSet" table="AB" inverse="true" lazy="false" fetch="select" cascade="all">
    <key>
        <column name="A_ID" not-null="true" />
    </key>
    <many-to-many class="objectB" >
        <column name="B_ID" not-null="true" />
    </many-to-many>
</set>

b.hbm.xml有

<set name="aSet" table="AB" inverse="false" lazy="false" fetch="select" cascade="all">
    <key>
        <column name="B_ID" not-null="true" />
    </key>
    <many-to-many class="objectA">
        <column name="A_ID" not-null="true" />
    </many-to-many>
</set>

//ObjectA.java has
private Set<ObjectB> bSet = new HashSet<objectB>(0);

//ObjectB.java has
private Set<ObjectA> aSet = new HashSet<objectA>(0);

从前端发送A对象作为带有B的集合的json,表A在AB未被触及时正确地更新.

有人能指出我哪里错了吗？
这是JSON

{
    "a_field1": "value1","a_field2": "value2","aId": 1,"bSet": [
        {
            "bId": 100
        },{
            "bId": 200
        }
   ],"a_field3": "value3"
}

最初,db在AB表中设置了3条记录

(1,100) 
(1,200) 
(1,300)

数据库中的最终结果应该是

(1,200)

应该删除最后一行(1,300).

任何帮助是极大的赞赏.

>沙阿