休眠 - 对象不声明

类

的实例，我有一个非常简单的实体：休眠 - 对象不声明

import javax.persistence.*; 

@Entity(name = "Message") 
public class MessageEntity { 

    private Long id; 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    public Long getId() { 
     return this.id; 
    } 

    public void setId(Long id) { 
     this.id = id; 
    } 
}

的的persistence.xml包含hibernate.hbm2ddl.auto=create-drop，所以表中创建的基础上正确的注释。不过，当我坚持的实体，我得到以下异常：

org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of org.acme.project.MessageEntity.id 
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:192) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:346) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4746) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4465) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:243) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:116) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:75) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:811) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:784) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:789) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1181) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final] 
... 154 more 
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.8.0_20] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) [rt.jar:1.8.0_20] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.8.0_20] 
at java.lang.reflect.Method.invoke(Method.java:483) [rt.jar:1.8.0_20] 
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:169) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
... 165 more

或者当字段注释，而不是吸气：

org.hibernate.PropertyAccessException: could not get a field value by reflection getter of org.acme.project.MessageEntity.id 
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:60) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:346) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4746) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4465) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:243) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:116) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:75) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:811) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:784) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:789) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1181) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final] 
... 154 more 
Caused by: java.lang.IllegalArgumentException: Can not set java.lang.Long field org.acme.project.MessageEntity.id to org.acme.project.MessageEntity 
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) [rt.jar:1.8.0_20] 
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) [rt.jar:1.8.0_20] 
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58) [rt.jar:1.8.0_20] 
at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36) [rt.jar:1.8.0_20] 
at java.lang.reflect.Field.get(Field.java:387) [rt.jar:1.8.0_20] 
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:57) [hibernate-core-4.3.7.Final.jar:4.3.7.Final] 
... 165 more

产生异常的代码是非常复杂的，所以采取了此刻真正得到它：

@PersistenceContext 
private EntityManager em; 

public void doMagic() { 
    this.em.persist(new MessageEntity()); 
}

这可能是一个小的，非常愚蠢的错误，使休眠认为它应该的ID设置为MessageEntity，但我看不到找到它在哪里。有什么问题？

来源

2016-02-19 Steffi S.

向我们展示实体的完整代码以及引发该异常的代码。 –

@JBNizet我添加了getter和setter。 –

您完全更改了代码，其中包含其他几个字段，关于构建器模式的注释以及SequenceGenerator。你是否仍然获得与上述实体相同的异常，包含单个id字段和身份生成器？ –

好的，这个例外根本无法解决问题的原因。我在EAR内部有一个WAR，并且WAR有EAR内库的重复。所以在内部可能有ClassCastException或其他东西，因为WAR中的对象不能被EAR内的bean使用。

来源

2016-02-19 13:04:07

休眠 - 对象不声明

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