无法从Java NamedQuery获取resultList

Question

@Override
public com.iranatelier.sistema.dominio.Probandoblob pruebaBajarImagen() throws Exception{
com.iranatelier.sistema.dominio.Probandoblob a = new com.iranatelier.sistema.dominio.Probandoblob();
        Probandoblob b = new Probandoblob();
        try {
        Query query = en.createNamedQuery("Probandoblob.findAll");


            List lista = query.getResultList();

            if (lista.size() > 0) {
                for(Object c : lista){
                    b = (Probandoblob) c;
                    a.setId(b.getId());
                    a.setImagen(b.getImagen());
                }
            }
        } catch (Exception e) {
            throw new Exception("Error en editarEntrega:", e);
        }
        return a;
    }

我有一个sql oracle table whit blob数据类型，当我尝试从数据库中获取select的结果时，sendme会出现此错误。

Exception Description: Could not deserialize object from byte array.
Internal Exception: java.io.StreamCorruptedException: invalid stream header: FFD8FFE0
Mapping: org.eclipse.persistence.mappings.DirectToFieldMapping[imagen-->JAAN.PROBANDOBLOB.IMAGEN]
Descriptor: RelationalDescriptor(com.iranatelier.sistema.entities.Probandoblob --> [DatabaseTable(JAAN.PROBANDOBLOB)])> 

实体是：

@Entity
@Table(name = "PROBANDOBLOB", catalog = "", schema = "JAAN")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Probandoblob.findAll", query = "SELECT p FROM Probandoblob p")
    , @NamedQuery(name = "Probandoblob.findById", query = "SELECT p FROM Probandoblob p WHERE p.id = :id")})
public class Probandoblob implements Serializable {

    private static final long serialVersionUID = 1L;
    // @Max(value=?)  @Min(value=?)//if you know range of your decimal fields consider using these annotations to enforce field validation
    @Id
    @Basic(optional = false)
    @NotNull
    @Column(name = "ID")
    private BigDecimal id;
    @Basic(optional = false)
    @NotNull
    @Lob
    @Column(name = "IMAGEN")
    private byte[] imagen;

我如何从数据库下载blob类型？