package ru.javatalks.dao;

import java.util.List;

public interface Dao<T> {
    /**
     * Base method for object saving (controls object inserting and updating).
     *
     * @param entity object to save
     */
    public void saveObject(T entity);

    /**
     * Base method for deleting a specified object
     *
     * @param entity a object to delete
     */
    public void deleteObject(T entity);

    /**
     * Base method for object deleting that bases on object class and id.
     *
     * @param id - an id (primary key) of the object
     */
    public void deleteObject(Number id);

    /**
     * Base method for extracting object that bases on object class and id. If
     * no object found returns null
     *
     * @param id the identifier (primary key) of the class
     * @return filled object
     */
    public T getObject(Number id);

    /**
     * Base method that used to extract all objects of concrete type. Like
     * record search in a table
     *
     * @return list of filled objects
     */
    public List<T> getAllObjects();

    /**
     * Get count of all objects of given type.
     *
     * @return count of objects
     */
    public int getAllObjectsCount();

    /**
     * The HQL, SQL or other request in the form of the prepared statement.
     *
     * @param request the request to database
     * @param values  values to put instead of "?"
     * @return list of objects that setisfy the criteria
     */
    public List<T> getObjects(String request, Object[] values);
}

package ru.javatalks.dao.hibernate;

import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import ru.javatalks.dao.Dao;

import java.util.List;

/**
 * Base class for hibernate DAO.
 *
 * @author nazica
 * @author ctapobep
 * @author unknown
 */
@SuppressWarnings("unchecked")
public class HibernateDao<T> extends HibernateDaoSupport implements Dao<T> {

    private Class entityClass;

    /**
     * Creates a dao that works with specified entity class.
     *
     * @param entityClass class to collaborate with database
     */
    public HibernateDao(Class entityClass) {
        this.entityClass = entityClass;
    }

    public List<T> getAllObjects() {
        return getHibernateTemplate().loadAll(getEntityClass());
    }

    public T getObject(Number id) {
        return (T) getHibernateTemplate().get(getEntityClass(), id);
    }

    public int getAllObjectsCount() {
        DetachedCriteria criteria = DetachedCriteria.forClass(getEntityClass()).setProjection(
                Projections.rowCount());
        return (Integer) getHibernateTemplate().findByCriteria(criteria).get(0);
    }

    public void saveObject(T object) {
        getHibernateTemplate().saveOrUpdate(object);
    }

    public void deleteObject(Number id) {
        getHibernateTemplate().delete(getObject(id));
    }

    public void deleteObject(T object) {
        getHibernateTemplate().delete(object);
    }

    /**
     * Finds objects by HQL.
     *
     * @param hql        query to find objects by
     * @param parameters parameters if query is prepared statement and contains "?"
     * @return objects that are match specified criteria
     */
    protected List<T> findByHQL(String hql, Object[] parameters) {
        return getHibernateTemplate().find(hql, parameters);
    }

    public List<T> getObjects(String request, Object[] values) {
        return findByHQL(request, values);
    }

    /**
     * Gets the class of the entity the DAO works with.
     *
     * @return the class of the entity the DAO works with
     */
    public Class<T> getEntityClass() {
        return entityClass;
    }

}

    <bean id="hibernateDao" class="ru.javatalks.dao.hibernate.HibernateDao" abstract="true">
        <property name="sessionFactory" ref="hibernateSessionFactory"/>
     </bean>
    <bean id="userDao" class="ru.javatalks.dao.hibernate.impl.UserDaoImpl" parent="hibernateDao">
        <constructor-arg value="ru.javatalks.dao.sample.User"/>
    </bean>