问题描述
我有一个DAO，我曾经使用JPA加载和保存我的域对象。我终于设法让事务处理工作了，现在我又遇到了另一个问题。
I've got a DAO that I used to load and save my domain objects using JPA. I finally managed to get the transaction stuff working, now I've got another issue.
在我的测试用例中，我调用我的DAO来加载一个给定的域对象id，检查它是否已加载，然后调用相同的DAO删除刚刚加载的对象。当我这样做时，我得到以下内容：
In my test case, I call my DAO to load a domain object with a given id, check that it got loaded and then call the same DAO to delete the object I just loaded. When I do that I get the following:
java.lang.IllegalArgumentException: Removing a detached instance mil.navy.ndms.conops.common.model.impl.jpa.Group#10
at org.hibernate.ejb.event.EJB3DeleteEventListener.performDetachedEntityDeletionCheck(EJB3DeleteEventListener.java:45)
at org.hibernate.event.def.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:108)
at org.hibernate.event.def.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:74)
at org.hibernate.impl.SessionImpl.fireDelete(SessionImpl.java:794)
at org.hibernate.impl.SessionImpl.delete(SessionImpl.java:772)
at org.hibernate.ejb.AbstractEntityManagerImpl.remove(AbstractEntityManagerImpl.java:253)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:600)
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:180)
at $Proxy27.remove(Unknown Source)
at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao.delete(GroupDao.java:499)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:600)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at $Proxy28.delete(Unknown Source)
at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDaoTest.testGroupDaoSave(GroupDaoTest.java:89)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:600)
at junit.framework.TestCase.runTest(TestCase.java:164)
at junit.framework.TestCase.runBare(TestCase.java:130)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:120)
at junit.framework.TestSuite.runTest(TestSuite.java:230)
at junit.framework.TestSuite.run(TestSuite.java:225)
at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
现在假设我使用相同的DAO实例，并且我没有更改EntityManagers（除非Spring没有让我知道），这怎么可能是一个独立的对象？
Now given that I'm using the same DAO instance, and I've not changed EntityManagers (unless Spring does so without letting me know), how can this be a detached object?
我的DAO代码如下所示：
My DAO code looks like this:
public class GenericJPADao<INTFC extends IAddressable, VO extends BaseAddressable> implements IWebDao, IDao<INTFC>, IDaoUtil<INTFC>
{
private static Logger logger = Logger.getLogger (GenericJPADao.class);
protected Class<?> voClass;
@PersistenceContext(unitName = "CONOPS_PU")
protected EntityManagerFactory emf;
@PersistenceContext(unitName = "CONOPS_PU")
protected EntityManager em;
public GenericJPADao()
{
super ( );
ParameterizedType genericSuperclass =
(ParameterizedType) getClass ( ).getGenericSuperclass ( );
this.voClass = (Class<?>) genericSuperclass.getActualTypeArguments ( )[1];
}
...
public void delete (INTFC modelObj, EntityManager em)
{
em.remove (modelObj);
}
@SuppressWarnings("unchecked")
public INTFC findById (Long id)
{
return ((INTFC) em.find (voClass, id));
}
}
测试用例代码如下：
IGroup loadedGroup = dao.findById (group.getId ( ));
assertNotNull (loadedGroup);
assertEquals (group.getId ( ), loadedGroup.getId ( ));
dao.delete (loadedGroup); // - This generates the above exception
loadedGroup = dao.findById (group.getId ( ));
assertNull(loadedGroup);
谁能告诉我这里我做错了什么？
Can anyone tell me what I'm doing wrong here?
推荐答案
我怀疑你在交易之外运行你的代码，所以你的找到和删除操作发生在单独的持久化上下文中， find 实际上返回分离的实例（因此JPA是对的，你 ARE 删除分离的对象）。
I suspect that you are running your code outside a transaction so your find and delete operations occur in a separate persistence context and the find actually returns a detached instance (so JPA is right and you ARE deleting a detached object).
在交易中包装你的查找/删除序列。
Wrap your find / delete sequence inside a transaction.
更新：以下：
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