Question

public class GenericDao <T, PK extends Serializable> {

    private final Class<T> type;

    @Resource(name = "sessionFactory")
    private SessionFactory sessionFactory;

    public GenericDao(final Class<T> type) {
    this.type = type;
    }

    public PK save(final T o) {
    return (PK) sessionFactory.getCurrentSession().save(o);
    }
// ... get,delete, etc

App context bean:

<bean id="fooDao" class="com.mycompany.dao.GenericDao">
        <constructor-arg>
            <value>com.mycompany.Foo</value>
        </constructor-arg>
    </bean>

And in service layer invoke like so :

@Autowired
private GenericDao<Foo, Integer> fooDao;
...
public doStuffIncludingSave(Foo foo)
fooDao.save(foo);

Answer 1

I think your solution is fine but you do not need the class parameter T. It just limits you and does not allow to re-use the same DAO for Integers and Strings (for example).

Save method does not need this type at all.

Methods like get() or find() should receive generic type themselves:

public <T> T findById(Class<T> clazz, Serializable id);

public <T> List<T> listAll( Class<T> clazz );