JAX-WS + Hibernate + JAXB：如何在编组期间避免LazyInitializationException [英] JAX-WS + Hibernate + JAXB: How to avoid LazyInitializationException during marshalling
问题描述
我有一个JAX-WS应用程序，它返回从Hibernate数据库后端（Oracle 10g或Oracle 11g）中获取的数据对象。我为此使用了javax.persistence.criteria.CriteriaQuery。它工作正常，除非对象具有依赖性，不应该为某些特定查询返回，例如：
@Immutable
@Entity
@Table（schema =some_schema，name =USER_VW）
public class User实现Serializable {
...
@ManyToOne（fetch = FetchType.LAZY）
@JoinColumn（name =PRFL_ID）
public Profile getProfile（）{...}
$ b $ public void setProfile个人资料配置文件）{...}
@ManyToOne（fetch = FetchType.LAZY）
@JoinColumn（name =SM_OTH_TP_ID）
public SomeOtherType getSomeOtherType（）{.. 。}
public void setSomeOtherType（SomeOtherType otherType）{...}
@ManyToOne（fetch = FetchType.LAZY）
@JoinColumn（name =SM_DPND_ID ）
public SomeDependency getSomeDependency（）{...}
public void setSomeDependency（SomeDependency dependency）{...}
...
}
以下是我的标准查询：
CriteriaBuilder cb = entityManager.getCriteriaBuilder（）;
CriteriaQuery< User> criteria = cb.createQuery（User.class）;
criteria.distinct（true）;
Root< User> user = criteria.from（User.class）;
加入<用户，个人资料> profileJoin = user.join（profile，JoinType.INNER）;
user.fetch（someOtherType，JoinType.LEFT）;
criteria.select（user）;
Predicate inPredicate = profileJoin.get（profileType）。in（types）;
criteria.where（inPredicate）;
注意：我不提取SomeDependency属性。我不希望它被返回。
这里是UserServiceResponse类的定义：
<$ p
@XmlRootElement（name =UserServiceResponse，namespace =...）
@XmlAccessorType（XmlAccessType.FIELD）
@XmlType（name =UserServiceResponse， namespace =...）
public class UserServiceResponse {
@XmlElementWrapper（name =users）
@XmlElement（name =user）
私人最终集合<用户>用户;
...
然后JAXB发现Hibernate Session已关闭。当它试图编组响应时，我得到以下异常：
原因：org.hibernate.LazyInitializationException：无法初始化代理 - 没有会话
在org.hibernate.proxy.AbstractLazyInitializer.initialize（AbstractLazyInitializer.java:164）[hibernate-core-4.2.7.SP1-redhat-3.jar：4.2.7.SP1-redhat-3 ]
在org.hibernate.proxy.AbstractLazyInitializer.getImplementation（AbstractLazyInitializer.java:285）[hibernate-core-4.2.7.SP1-redhat-3.jar：4.2.7.SP1-redhat-3]
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke（JavassistLazyInitializer.java:185）[hibernate-core-4.2.7.SP1-redhat-3.jar：4.2.7.SP1-redhat-3 ]
at com.myproject.model.user.entity.SomeDependency _ $$ _ jvsteec_98.getCode（SomeDependency _ $$ _ jvsteec_98.java）
...
at com.sun。 xml.bind.v2.runtime.XMLSerializer.childAsRoot（XMLSerializer.java:494）
at com.sun.xml.bind.v2.runtime.MarshallerImpl.write（MarshallerImpl.java:323）
at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal（MarshallerImpl.java:251）
at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal（AbstractMarshallerImpl.java:74）[jboss -jaxb-api_2.2_spec-1.0.4.Final-redhat-2.jar：1.0.4.Final-redhat-2]
at org.apache.cxf.jaxb.JAXBEncoderDecoder.writeObject（JAXBEncoderDecoder.java：
at org.apache.cxf.jaxb.JAXBEncoderDecoder.marshall（JAXBEncoderDecoder.java：612）[cxf-rt-databinding-jaxb-2.7.7.redhat-1.jar：2.7.7.redhat-1] 240）[cxf-rt-databinding-jaxb-2.7.7.redhat-1.jar：2.7.7.redhat-1]
... 32 more
当marshaller尝试为SomeDependency类的code属性（它是HibernateProxy实例）获取值时，会发生这种情况。
现在我看到的解决方案是添加某种过滤器，它在编组期间检查是否该对象是HibernateProxy的实例。如果它是一个HibernateProxy实例，则过滤器处理它，如果不是，则保留其默认行为。
我该怎么做？使用XmlJavaTypeAdapter类？或者使用com.sun.xml.internal.bind.v2.runtime.reflect.Accessor？
如果有人能告诉我任何其他方式来解决我的问题，我会赞赏。注意：我在其他Web服务中的JAX-WS内部以及应用程序的其他模块中的JAX-WS之外重复使用相同的Hibernate代码和POJO，其中延迟加载是一个优势。
更新：
XmlJavaTypeAdapter，但它不适合我。我创建了一个新的适配器--HibernateProxyAdapter，它扩展了XmlJavaTypeAdapter。用户实体并不是我拥有的唯一POJO，事实上，它们有很多。为了确保适配器适用于所有这些适配器，我将它添加到了包级别。
@XmlJavaTypeAdapters（
@XmlJavaTypeAdapter（value = HibernateProxyAdapter.class，type = HibernateProxy.class）
）
package com.myproject.model.entity;
以下是适配器：
public class HibernateProxyAdapter extends XmlJavaTypeAdapter< Object，Object> {
public Object unmarshal（Object v）throws Exception {
return null; //不需要解组HibernateProxy实例
$ b $ public Object marshal（Object v）抛出Exception {
if（v！= null）{
if （v HibernateProxy的实例）{
LazyInitializer lazyInitializer =（（HibernateProxy）v）.getHibernateLazyInitializer（）;
if（lazyInitializer.isUninitialized（））{
return null;
} else {
//现在不做任何事
}
} else if（v instanceof PersistentCollection）{
if（（（PersistentCollection）v）.wasInitialized ））{
//获得了一个初始化集合
} else {
return null;
}
}
}
return v;
$ / code $ / pre
现在我又遇到了另一个异常： 导致：javax.xml.bind.JAXBException：类org.hibernate.collection.internal.PersistentSet或其任何超类是已知的在这方面。
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getBeanInfo（JAXBContextImpl.java:588）
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType（XMLSerializer。 java：648）
... 57 more
据我所知，尝试编组初始化的hibernate集合，例如：org.hibernate.collection.internal.PersistentSet。我没有理由...... PersistentSet实现Set接口。我认为JAXB应该知道如何处理它。任何想法？
更新2：
我也尝试了使用Accessor类的第二个解决方案。这是我的访问器：
public class JAXBHibernateAccessor extends Accessor {
private final Accessor accessor;
protected JAXBHibernateAccessor（Accessor accessor）{
super（accessor.getValueType（））;
this.accessor = accessor;
}
@Override
public Object get（Object bean）抛出AccessorException {
return Hibernate.isInitialized（bean）？ accessor.get（bean）：null;
}
@Override
public void set（Object bean，Object value）throws AccessorException {
accessor.set（bean，value）;
AccessorFactory ...
public class JAXBHibernateAccessorFactory implements AccessorFactory {
private final AccessorFactory accessorFactory = AccessorFactoryImpl.getInstance（）;
$ b $ @Override
public Accessor createFieldAccessor（Class bean，Field field，boolean readOnly）throws JAXBException {
return new JAXBHibernateAccessor（accessorFactory.createFieldAccessor（bean，field，readOnly））;
$ b @Override
public Accessor createPropertyAccessor（Class bean，Method getter，Method setter）throws JAXBException {
return new JAXBHibernateAccessor（accessorFactory.createPropertyAccessor（bean，getter ，setter））;
package-info.java ...
@XmlAccessorFactory（JAXBHibernateAccessorFactory.class）
package com.myproject.model.entity;
现在我需要在JAXB上下文中启用自定义的AccessorFactory / Accessor支持。我尝试将自定义的JAXBContextFactory添加到Web服务定义中，但它不起作用...
$ b $ pre $ $ $ c $ @WebService
@ UsesJAXBContext（JAXBHibernateContextFactory.class）
public interface UserService {
...
}
这里是我的contextFactory
public class JAXBHibernateContextFactory implements JAXBContextFactory {
@Override
public JAXBRIContext createJAXBContext（@NotNull SEIModel seiModel，@NotNull List< Class>类，
@NotNull List< TypeReference> typeReferences）throws JAXBException {
return ContextFactory.createContext（classes.toArray（new Class [classes.size（）]），typeReferences，
null，null，false，new RuntimeInlineAnnotationReader（），true，false，false）;
}
}
我不知道为什么，但是创建JAXBContext方法从不调用。看起来像@UsesJAXBContext注释什么都不做......
有谁知道如何使它工作？
或者如何在JAX-WS中将com.sun.xml.bind.XmlAccessorFactoryJAXBContext属性设置为true？
顺便说一句，我忘了提及它，我将它部署到JBoss EAP 6.2中。
我认为注释 @XmlTransient 是为了这个。将它添加到你的属性 someDependency 以使JAXB忽略这个字段。
@XmlTransient
@ManyToOne（fetch = FetchType.LAZY）
@JoinColumn（name =SM_DPND_ID）
Public SomeDependency getSomeDependency（）{...}
更新以下评论：如果您必须使用适配器选项，我的猜测是您必须：
- 为实体用户创建一个新适配器，用于扩展XmlAdapter
- 每个属性的编组，并使用方法
Hibernate.isInitialized（yourObject.getSomeDependency（））来测试关联是否在调用编组之前被加载过。 - 用适当的属性添加
@XmlJavaTypeAdapter来声明它实体用户
也许可以通过直接为属性 someDependency 创建一个适配器来完成，但您可能会希望在JAXB尝试将该属性传递给适配器时发生LazyInitializationException。
I have a JAX-WS application, which returns data objects, that were fetched from a Hibernate Database backend (Oracle 10g or Oracle 11g). I use javax.persistence.criteria.CriteriaQuery for that. It works fine, unless the object has dependencies, which should not be returned for some specific queries, e.g.:
@Immutable
@Entity
@Table(schema = "some_schema", name = "USER_VW")
public class User implements Serializable {
...
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "PRFL_ID")
public Profile getProfile() {...}
public void setProfile(Profile profile) {...}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "SM_OTH_TP_ID")
public SomeOtherType getSomeOtherType() {...}
public void setSomeOtherType(SomeOtherType otherType) {...}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "SM_DPND_ID)
public SomeDependency getSomeDependency() {...}
public void setSomeDependency(SomeDependency dependency) {...}
...
}
Here is my criteria query:
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<User> criteria = cb.createQuery(User.class);
criteria.distinct(true);
Root<User> user = criteria.from(User.class);
Join<User, Profile> profileJoin = user.join("profile", JoinType.INNER);
user.fetch("someOtherType", JoinType.LEFT);
criteria.select(user);
Predicate inPredicate = profileJoin.get("profileType").in(types);
criteria.where(inPredicate);
NOTE: I don't fetch SomeDependency property. I don't want it to be returned.
And here is the definition of the UserServiceResponse class:
@XmlRootElement(name = "UserServiceResponse", namespace = "...")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "UserServiceResponse", namespace = "...")
public class UserServiceResponse {
@XmlElementWrapper(name = "users")
@XmlElement(name = "user")
private final Collection<User> users;
...
Then JAXB finds that the Hibernate Session has been closed. When it tries to marshall the response I get the following exception:
Caused by: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:164) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:285) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185) [hibernate-core-4.2.7.SP1-redhat-3.jar:4.2.7.SP1-redhat-3]
at com.myproject.model.user.entity.SomeDependency_$$_jvsteec_98.getCode(SomeDependency_$$_jvsteec_98.java)
...
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:494)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:323)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:251)
at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:74) [jboss-jaxb-api_2.2_spec-1.0.4.Final-redhat-2.jar:1.0.4.Final-redhat-2]
at org.apache.cxf.jaxb.JAXBEncoderDecoder.writeObject(JAXBEncoderDecoder.java:612) [cxf-rt-databinding-jaxb-2.7.7.redhat-1.jar:2.7.7.redhat-1]
at org.apache.cxf.jaxb.JAXBEncoderDecoder.marshall(JAXBEncoderDecoder.java:240) [cxf-rt-databinding-jaxb-2.7.7.redhat-1.jar:2.7.7.redhat-1]
... 32 more
It happens when marshaller tries to get value for the "code" property of SomeDependency class which is a HibernateProxy instance.
The solution that I see for now is to add some kind of "filter" which checks during marshalling if the object is instance of HibernateProxy or not. If it is a HibernateProxy instance the filter handle it, if not, just leaves its default behavior.
How can I do that? Using a XmlJavaTypeAdapter class? Or using com.sun.xml.internal.bind.v2.runtime.reflect.Accessor?
If anyone can tell me any other way to solve my problem I would be appreciated.
NOTE: I'm reusing the same Hibernate code and POJOs, inside JAX-WS in other web-services and outside JAX-WS in other modules of the application, where lazy loading is an advantage.
UPDATE:
I've tried using XmlJavaTypeAdapter but it didn't work for me. I created a new adapter - HibernateProxyAdapter which extends XmlJavaTypeAdapter. User entity is not the only POJO that I have, in fact, there are a lot of them. To ensure that the adapter is applied to all of them I added it on the package level.
@XmlJavaTypeAdapters(
@XmlJavaTypeAdapter(value=HibernateProxyAdapter.class, type=HibernateProxy.class)
)
package com.myproject.model.entity;
Here is the adapter:
public class HibernateProxyAdapter extends XmlJavaTypeAdapter<Object, Object> {
public Object unmarshal(Object v) throws Exception {
return null; // there is no need to unmarshall HibernateProxy instances
}
public Object marshal(Object v) throws Exception {
if (v != null) {
if ( v instanceof HibernateProxy ) {
LazyInitializer lazyInitializer = ((HibernateProxy) v ).getHibernateLazyInitializer();
if (lazyInitializer.isUninitialized()) {
return null;
} else {
// do nothing for now
}
} else if ( v instanceof PersistentCollection ) {
if(((PersistentCollection) v).wasInitialized()) {
// got an initialized collection
} else {
return null;
}
}
}
return v;
}
}
Now i'm getting another exception:
Caused by: javax.xml.bind.JAXBException: class org.hibernate.collection.internal.PersistentSet nor any of its super class is known to this context.
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getBeanInfo(JAXBContextImpl.java:588)
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:648)
... 57 more
As I understand, this happens when it tries to marshal an initialized hibernate collection, e.g.: org.hibernate.collection.internal.PersistentSet. I don't get the reason... PersistentSet implements Set interface. I thought JAXB should know how to handle it. Any ideas?
UPDATE 2: I have also tried the second solution using Accessor class. Here is my accessor:
public class JAXBHibernateAccessor extends Accessor {
private final Accessor accessor;
protected JAXBHibernateAccessor(Accessor accessor) {
super(accessor.getValueType());
this.accessor = accessor;
}
@Override
public Object get(Object bean) throws AccessorException {
return Hibernate.isInitialized(bean) ? accessor.get(bean) : null;
}
@Override
public void set(Object bean, Object value) throws AccessorException {
accessor.set(bean, value);
}
}
AccessorFactory...
public class JAXBHibernateAccessorFactory implements AccessorFactory {
private final AccessorFactory accessorFactory = AccessorFactoryImpl.getInstance();
@Override
public Accessor createFieldAccessor(Class bean, Field field, boolean readOnly) throws JAXBException {
return new JAXBHibernateAccessor(accessorFactory.createFieldAccessor(bean, field, readOnly));
}
@Override
public Accessor createPropertyAccessor(Class bean, Method getter, Method setter) throws JAXBException {
return new JAXBHibernateAccessor(accessorFactory.createPropertyAccessor(bean, getter, setter));
}
}
package-info.java ...
@XmlAccessorFactory(JAXBHibernateAccessorFactory.class)
package com.myproject.model.entity;
Now I need to enable custom AccessorFactory/Accessor support on the JAXB context. I tried adding custom JAXBContextFactory to the web service definition but it didn't work...
@WebService
@UsesJAXBContext(JAXBHibernateContextFactory.class)
public interface UserService {
...
}
and here is my contextFactory
public class JAXBHibernateContextFactory implements JAXBContextFactory {
@Override
public JAXBRIContext createJAXBContext(@NotNull SEIModel seiModel, @NotNull List<Class> classes,
@NotNull List<TypeReference> typeReferences) throws JAXBException {
return ContextFactory.createContext(classes.toArray(new Class[classes.size()]), typeReferences,
null, null, false, new RuntimeInlineAnnotationReader(), true, false, false);
}
}
I don't know why but createJAXBContext method is never invoked. Looks like @UsesJAXBContext annotation does nothing...
Does anyone know how to make it work? Or how can I set the "com.sun.xml.bind.XmlAccessorFactory" JAXBContext property to true inside JAX-WS?
BTW, I forgot to mention, I deploy it to JBoss EAP 6.2.
I think annotation @XmlTransient is meant for this. Add it to your property someDependency to make JAXB ignore this field.
@XmlTransient
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "SM_DPND_ID)
public SomeDependency getSomeDependency() {...}
Update following comments: If you must go for the adapter option, my guess is you have to :
- Create a new adapter for entity User extending XmlAdapter
- In your adapter call the marshaller for each of your property and use method
Hibernate.isInitialized(yourObject.getSomeDependency())to test if the association has been loaded before calling the marshaller or not. - declare it by adding
@XmlJavaTypeAdapterwith the proper attribute to your entity User
Maybe it can be done by creating directly an adapter for the property someDependency but you might expect a LazyInitializationException when JAXB will try to pass the property to the adapter.
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