Typically, you might serialise to a ByteArrayOutputStream then write the byte array to the BLOB. To read, get the byte array from the BLOB then deserialise from a ByteArrayInputStream based on that array.
If you don't know how to serialise/deserialise to/from streams, read up on Java Serialisation, independent of databases.
As a possible optimisation, note that Blob objects have built-in InputStream and OutputStream functionality, from Java 1.4 onwards.
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.