Javax.sql.rowset.serial.SerialBlob cannot be cast to oracle.sql.BLOB

Question

Hi there,
I'm facing this exception.
My code:
final ReportTemplateAttachment rta = new ReportTemplateAttachment();
FileBlob fb = new FileBlob();
fb.setContentType(attachmentDto.getContentType().getValue());
fb.setCreationDate(sysDate);
fb.setCreationUser(userId);
final SerialBlob blob = new SerialBlob(attachmentDto.getFileVal());//it's a  byte[]
//SerialBlob is of type javax.sql.rowset.serial.SerialBlob
fb.setFileData(blob);
fb.setName(attachmentDto.getFileName());
fb.setLastUpdateDate(sysDate);
fb.setLastUpdateUser(userId);
fb.setLength(blob.length());
rta.setFileBlob(fb);and the object rta will be inserted into another object.
The variable of interest in FileBlob hbm is defined as follows:
<property name="fileData" type="blob">
            <column name="FILE_DATA" />
</property>where the type blob is oracle.sql.BLOB
If I change the oracle.sql.BLOB to javax.sql.rowset.serial.SerialBlob in the hbm, I can insert but when I try to get the blob back I get a deserialize exception so this change is not an option.
but when I save the main Object (a cascade operation) I get the following exception:
org.springframework.jdbc.UncategorizedSQLException:
Hibernate flushing: could not insert: [pt.sc.data.entities.FileBlob];
uncategorized SQLException for SQL
[insert into WP_ADMIN.file_blob (name, content_type, length, file_data, status, creation_user, creation_date, last_update_user, last_update_date, id)
values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)];
SQL state [null];
error code [0];
An SQLException was provoked by the following failure: java.lang.ClassCastException:
javax.sql.rowset.serial.SerialBlob cannot be cast to oracle.sql.BLOB;
nested exception is java.sql.SQLException: An SQLException was provoked by the following failure:
java.lang.ClassCastException: javax.sql.rowset.serial.SerialBlob cannot be cast to oracle.sql.BLOBAny light on the subject?
Thanks in advance,
mleiria

Answer 1

You don't seem to understand the difference between an object model and a database. Hibernate, being an ORM package, works on the object model and will, based on what you request it to do, generate proper SQL statements to get the database part going. But you shouldn't be thinking about databases when using Hibernate; your main focus is the object model. There is no blob, only binary data. Binary data in Java is generally handled through a byte array.
If you want to think in databases where blobs do exist, you should be using JDBC directly, not Hibernate.
(I'm far from being an expert in Hibernate)I would really suggest taking a few hours and reading through the manual. You don't need to be an expert but you should at least know what kind of tool you're working with.