I am using Hibernat 3.3.1, and Hibernate JPA implementation to implemet EJB 3 application. I have a table (APPLICATION), which has a BLOB field (named ART) corresponding to an image file. My entity class is the follwoing

@Entity
@Table(name="APPLICATION", schema="TEST_OWNER")
public class Application implements Serializable{
.....
@Lob
@Basic(fetch=FetchType.LAZY)
@Column(name="ART")
private byte[] art;

}

and my sessionbean is the following

@Stateless
public class ApplicationManagerBean
{
@PersistenceContext(unitName="MyPU")
private EntityManager em;
.......
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void createApplication(Application app, RequestContext rc)
{
byte[] b = convertFileToByteArray(app.getImage());
app.setArt(b);
em.persist(app);
}
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void updateApplication (Application app, RequestContext rc)
{
byte[] b = convertFileToByteArray(app.getImage());
app.setArt(b);
em.merge(app);
}

private byte[] convertFileToByteArray(File file)
{
FileInputStream fis = null;
byte[] b = null;
try{
fis = new FileInputStream(file);
b = new byte[(int) file.length()];
fis.read(b);
}catch(IOException e){
log.error("Error in reading the art file, make sure the file exists.",e);
}finally{
try{
if(fis !=null) fis.close();
}catch(IOException e){}
}
return b;
}
}
I could successfully and save or update an APPLICATION record with image uploaded (i.e ART field). The only problem is I cannot lazily load this field. However After I instrumented my Application.class as instructed from hibernate documention

<taskdef name="instrument" classname="org.hibernate.tool.instrument.cglib.InstrumentTask">
<classpath refid="classpath"/>
</taskdef>
<instrument verbose="false">
<fileset dir="somepath/">
<include name="Application.class"/>
</fileset>
</instrument>

Now, I can lazily load the art field with existing records. But, when I tried to upload a new image to update or create a new record, it gave the follwoing the exception:

I am wondering why instrumentation can impact data saving. Your help is greatly appreciated.

[4/26/10 11:49:45:746 EDT] 00000020 ExceptionUtil E CNTR0020E: EJB threw an unexpected (non-declared) exception during invocation of method "updateApplication" on bean "BeanId(BessyEAR#BessyEJB.jar#ApplicationManagerBean, null)". Exception data: java.lang.ClassCastException: org.hibernate.intercept.LazyPropertyInitializer$1 incompatible with [B
at org.hibernate.type.ByteArrayBlobType.isEqual(ByteArrayBlobType.java:45)
at org.hibernate.type.AbstractLobType.isEqual(AbstractLobType.java:26)
at org.hibernate.type.ByteArrayBlobType.replace(ByteArrayBlobType.java:188)
at org.hibernate.type.TypeFactory.replace(TypeFactory.java:505)
at org.hibernate.event.def.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:392)
at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:319)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:167)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:81)
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:704)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:688)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:692)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:235)
at com.ibm.ws.jpa.management.JPAExEmInvocation.merge(JPAExEmInvocation.java:335)
at com.ibm.ws.jpa.management.JPAEntityManager.merge(JPAEntityManager.java:123)
at com.boeing.he.bessy.bean.admin.ApplicationManagerBean.updateApplication(ApplicationManagerBean.java:174)