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我有 3 个实体，分别命名为Discipline、DisciplineMembership、DisciplineManagement：

一个Discipline有很多DisciplineMemberships
一个Discipline有很多DisciplineManagements
一个DisciplineManagement 与 DisciplineMembership有一对一的关系

Discipline 的相关 hbm 文件的相关部分如下所示：

纪律.hbm： 

<class name="Discipline" table="DISCIPLINES">
    <id name="id" type="java.lang.Long">
        <generator class="increment" />
    </id>  

    <set name="memberships" inverse="false" cascade="all-delete-orphan" >
        <key column="disciplineId" not-null="true" />
        <one-to-many class="DisciplineMembership" />
    </set>  

    <set name="managements" inverse="false" cascade="all-delete-orphan">
        <key column="disciplineId" not-null="true" />
        <one-to-many class="DisciplineManagement" />
    </set>  

</class>

在一个名为A的函数中，我想遍历一个 Discipline 的 DisciplineMemberships 和 DiscipilineManagements：

public void A(){
    Discipline discipline = this.getObject();
    for(DisciplineMembership mem: discipline.getMembers()){
        System.out.print(mem);
    }
    for(DisciplineManagement man: discipline.getManagements()){
        System.out.print(man);
    }
}

第一个for语句运行正确，但在第二个中，我捕获 LazyInitializationException 如下：

13-04-27 13:54:26,115 [hibernate.LazyInitializationException (<init>:42)] ERROR: failed to lazily initialize a collection of role: Discipline.managements, no session or session was closed 
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: Discipline.managements, no session or session was closed
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
    at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368)
    at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
    at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:186)
    at ObjectManagementPart_Edit.A(ObjectManagementPart_Edit.java:6)

我很困惑这怎么可能？Discipline Session 是打开的，我可以遍历它的成员，但是当我想遍历它的管理时，hibernate 不能lazyInitialize 它们。

我应该怎么办？

更新： 我尝试使用 Hibernate.initialize() 函数，所以函数 A 现在是这样的：

public void A(){
    Discipline discipline = this.getObject();
    Hibernate.initialize(discipline.getMembeships());
    for(DisciplineMembership mem: discipline.getMemberships()){
        System.out.print(mem);
    }
    Hibernate.initialize(discipline.getManagements());
    for(DisciplineManagement man: discipline.getManagements()){
        System.out.print(man);
    }
}

第一次将 Hibernate.initialize() 用于Membeships没有问题，但在第二次用于管理时，我得到了这个异常：

org.hibernate.HibernateException: collection is not associated with any session
    at org.hibernate.collection.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:474)
    at org.hibernate.Hibernate.initialize(Hibernate.java:431)
    at discipline.ObjectManagementPart_Edit.A(ObjectManagementPart_Edit.java:6)

现在我更困惑了：/

4

1 回答 1

1

仅仅因为您可以迭代成员资格并不能告诉您它实际上只是让他们变得懒惰。如果之前加载的成员资格（会话打开的地方），它们将被保留。如果列表已经初始化，Hibernate.initialize(...) 将不会做任何事情。

要获得更准确的答案，您需要描述您的会话管理策略。hibernate 的大多数问题都源于会话管理不好这一事实。

于 2013-04-27T15:07:51.243 回答