Question

将项目从Hibernate 3升级到Hibernate 4时，抛出了NonUniqueObjectException。我创建了最小的Hibernate 4项目用于测试目的，并设法通过以下方式重现此异常：

拥有实体House，以及具有包含House实体

的复合ID的另一个实体Door

<class dynamic-insert="true" dynamic-update="true" name="entity.Door" select-before-update="true" table="DOOR">
<composite-id name="id" class="DoorHousePK">
    <key-many-to-one class="entity.House" column="HOUSEID" name="house"/>
    <key-property column="DOORID" name="doorId" type="string"/>
</composite-id>

然后在同一事务中获取一个House，然后通过复合ID获取Door：

（门）session.get（Door.class，doorHousePK）

以下是House的hbm文件：

<class dynamic-insert="true" dynamic-update="true" name="entity.House" select-before-update="true" table="HOUSE">
        <id column="ID" name="id" type="int"/>
        <property column="squarefeet" name="squareFeet" not-null="false" type="int"/>
        <property column="address" length="255" name="address" not-null="false" type="string"/>
        <property column="color" length="32" name="color" not-null="false" type="string"/>
        <property column="description" name="description" not-null="false" type="materialized_clob"/>
    </class>

，以及错误的堆栈跟踪：

INFO: HHH000327: Error performing load command : org.hibernate.NonUniqueObjectException: A different object with the same identifier value was already associated with the session : [entity.House#1]
Exception in thread "main" org.hibernate.NonUniqueObjectException: A different object with the same identifier value was already associated with the session : [entity.House#1]
    at org.hibernate.engine.internal.StatefulPersistenceContext.checkUniqueness(StatefulPersistenceContext.java:617)
    at org.hibernate.event.internal.AbstractReassociateEventListener.reassociate(AbstractReassociateEventListener.java:74)
    at org.hibernate.event.internal.DefaultLockEventListener.onLock(DefaultLockEventListener.java:95)
    at org.hibernate.internal.SessionImpl.fireLock(SessionImpl.java:774)
    at org.hibernate.internal.SessionImpl.fireLock(SessionImpl.java:767)
    at org.hibernate.internal.SessionImpl.access$1800(SessionImpl.java:176)
    at org.hibernate.internal.SessionImpl$LockRequestImpl.lock(SessionImpl.java:2491)
    at org.hibernate.loader.plan.exec.internal.EntityLoadQueryDetails$EntityLoaderRowReader.addKeyManyToOnesToSession(EntityLoadQueryDetails.java:263)
    at org.hibernate.loader.plan.exec.internal.EntityLoadQueryDetails$EntityLoaderRowReader.readRow(EntityLoadQueryDetails.java:247)
    at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:129)
    at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:138)
    at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:102)
    at org.hibernate.loader.entity.plan.AbstractLoadPlanBasedEntityLoader.load(AbstractLoadPlanBasedEntityLoader.java:186)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4126)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:503)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:468)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:213)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:275)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:151)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1070)
    at org.hibernate.internal.SessionImpl.access$2000(SessionImpl.java:176)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2551)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:955)

当将这个最小的项目还原回Hibernate 3时，异常消失了，一切正常。

Hibernate 3和Hibernate 4之间的复合id处理有什么区别？如何在Hibernate 4中完成这项工作？

Answer 1

我最近从hibernate 3迁移到了4个带有复合ID的表，并且通过复合外键相互关联。完全相同的配置在两个版本中都运行良好。因此，就复合id功能的基本概念而言，没有区别。

您应该为hibernate API启用调试，例如将org.hibernate。*的调试级别设置为日志属性文件中的DEBUG，以查看正在触发的SQL。这将帮助您查看hibernate是否正在触发任何其他/意外的SQL。

Answer 2

确保您的实体以及构成复合主键的对象具有hashCode（）和equals（）的适当实现。我似乎记得Hibernate 3和4之间的哈希码使用和/或对象相等性检查存在一些潜在的变化。

Hibernate 4 composite-id NonUniqueObjectException

2 个答案: