@Entity
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Lob
    private String contentStr;

    @Lob
    private byte[] imageByte;

    @Lob
    @Basic(fetch = FetchType.LAZY)
    private Blob imageBlob;

    @Lob
    private Clob contentClob;
   
    //getters setters
}

Alternatively, you can switch the type of property in your Java class. JDBC supports locator objects (LOBs) directly.
 If your Java property is java.sql.Clob or 
java.sql.Blob, you get lazy loading without bytecode instrumentation

java.sql.Blob and java.sql.Clob are the most efficient way to handle large objects in Java. Unfortunately, an instance of Blob or Clob
 is only useable until the JDBC transaction completes. So if your persistent class defines a property of java.sql.Clob or
 java.sql.Blob (not a good idea anyway), 
you’ll be restricted in how instances of the class may be used. In particular,
 you won’t be able to use instances of that class as detached objects. 
Furthermore, many JDBC drivers don’t feature working support for java.sql.Blob and java.sql.Clob.

 @Lob
    private String contentStr;

    @Lob
    private byte[] imageByte;

       EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        em.persist(createBook(em));
        em.getTransaction().commit();
        em.close();


        em = emf.createEntityManager();
        Book book = em.find(Book.class,1L);
        em.close();

select
        book0_.id as id1_0_0_,
        book0_.contentClob as contentClob2_0_0_,
        book0_.contentStr as contentStr3_0_0_,
        book0_.imageBlob as imageBlob4_0_0_,
        book0_.imageByte as imageByte5_0_0_ 
    from
        Book book0_ 
    where
        book0_.id=?

javax.persistence.jdbc.driver=oracle.jdbc.driver.OracleDriver
hibernate.dialect=org.hibernate.dialect.Oracle10gDialect