<bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.use_identifier_rollback">true</prop>
                <prop key="hibernate.format_sql">true</prop>
            </props>
        </property>

            try {
                obj = service.save(obj);
            }
            catch (ObjAlreadyExists e) {
                bindingResult.rejectValue("obj", "NotUnique.obj.name");
                return InitObjEditModel(obj, "edit");
            }
            catch (ObjNotFound e) {
                bindingResult.rejectValue("obj", "NotFound.obj.id");
                return InitObjEditModel(obj, "edit");
            }

public final class Exceptions {

    private Exceptions() {}

    public static class UserAlreadyExists extends DuplicateKeyException {
        public UserAlreadyExists(User user, Throwable cause) {
            super("User id [" + user.getUsername() + "] already exists", cause);
        }
    }

    public static class UserNotFound extends DataRetrievalFailureException {
        public UserNotFound(User user, Throwable cause) {
            super("User id [" + user.getId() + "] not found", cause);
        }
    }
}

            ...
            try {
                user = userService.save(user);
            }
            // уже существует
            catch (Exceptions.UserAlreadyExists e) {
                bindingResult.rejectValue("username", "NotUnique.user.username");
                return InitUserEditModel(user, error_cmd);
            }
            // не найден (возможно был удален)
            catch (Exceptions.UserNotFound e) {
                bindingResult.rejectValue("username", "NotFound.user.username");
                return InitUserEditModel(user, error_cmd);
            }
            ...

    @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public User save(User user) {

        User copyUser = new User(user);
        userDAO.save(copyUser);
        return copyUser;
    }

    @Override
    public void save(User user) {

        try {
            if (user.getId() == null)
                insert(user);
            else
                update(user);
        }
        catch (DuplicateKeyException e) {
            throw new Exceptions.UserAlreadyExists(user, e);
        }
    }

    private void update(User user) {
        ...
        if (jdbcTemplate.update(SQL, params) == 0)
            throw new Exceptions.UserNotFound(user, null);
    }

    @Override
    public void save(User user) {

        try {
            getCurrentSession().saveOrUpdate(user);
            getCurrentSession().flush();
        }
        catch(ConstraintViolationException e) {
            throw new Exceptions.UserAlreadyExists(user, e);
        }
        catch(StaleStateException e) {
            throw new Exceptions.UserNotFound(user, e);
        }
    }

<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>