Parametrized DAO problem

[blipsman]

Hi,

I am trying to use parameterized DAO which is everyone knows from Hibernate website :
This is the interface:

public interface DaoGeneric<T extends MyBaseEntity, ID extends Serializable>{

public T findById(ID id);

public List<T> findAll();

public void makeObjectPersistent(T entity);

public void makeObjectTransient(T entity);

public void flushSession();

public void clear();

}

public abstract class DaoGenericHibernate<T extends MyBaseEntity,
ID extends Serializable> extends
HibernateDaoSupport implements DaoGeneric<T, ID> {


private Class<T> persistentType;

public DaoGenericHibernate() {

this.persistentType = (Class<T>)
((ParameterizedType) getClass().getGenericSuperclass())
.getActualTypeArguments()[0];
}

public List<T> findAll() {
final List<T> loadedEntities = getHibernateTemplate().loadAll(getPersistentType() );
return loadedEntities;
}

public T findById(Serializable id) {
T loadedEntity = (T) getHibernateTemplate().get(getPersistentType(), id);
return loadedEntity;
}

public void makeObjectPersistent(T entity) {
getHibernateTemplate().saveOrUpdate(entity);
}

public void makeObjectTransient(T entity) {
getHibernateTemplate().delete(entity);
}

public void flushSession() {
getHibernateTemplate().flush();
}

public void clear() {
getHibernateTemplate().clear();
}

public Class<T> getPersistentType() {
return this.persistentType;
}

public List<T> findEntityByNamedQuery (String queryName, Object[] values) {
List<T> result = getHibernateTemplate().findByNamedQuery(queryName, values);

return result;
}

The DAO that is inheriting the Generic DAO is com.HibernateDaoImpl


When I am trying to invoke
the

findById(Serializable id)

I am getting error:

[com.HibernateDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType .......

This error occurs when

this.persistentType = (Class<T>)
((ParameterizedType) getClass().getGenericSuperclass())
.getActualTypeArguments()[0];

is being executed.

Any idea how to deal with this issue

I am using Hibernate 3.2
Spring 2.5
And a lot of patience and persistence.

Thanks

[krancour]

I'm not a Hibernate expert by any means, but could I suggest that if you post the code for your HibernateDaoImpl class?

[blipsman]

hey Kent,

In the com.HibernateDaoImpl I have method loadSomeEntity which is delegates
load processing to the

findById

here is the method:

public SomeEntity loadSomeEntity (Long id) {

SomeEntity someEntity = (SomeEntity ) super.findById(id);
}

The solution I've found is to provide as the second parameter to the loadSomeEntity () the actual class of the entity I am attempting to load.

It works, but I am still puzzled.

I did find some blog from Rob Harrop that migt help me, but at this point
I have not found solution on how to find actual entity type at the moment of execution.
thx