br.com.arsmachina.dao.hibernate.BaseHibernateDAO.java Source code

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Here is the source code for br.com.arsmachina.dao.hibernate.BaseHibernateDAO.java

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// Copyright 2008 Thiago H. de Paula Figueiredo
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package br.com.arsmachina.dao.hibernate;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import org.hibernate.SessionFactory;
import org.hibernate.classic.Session;
import org.hibernate.metadata.ClassMetadata;

/**
 * Superclass of both {@link ReadableDAOImpl} and {@link WriteableDAOImpl}.
 * 
 * @author Thiago H. de Paula Figueiredo
 * @param <T> the entity class related to this DAO.
 * @param <K> the type of the field that represents the entity class' primary key.
 */
public class BaseHibernateDAO<T, K extends Serializable> {

    private final SessionFactory sessionFactory;

    private final Class<T> entityClass;

    private final ClassMetadata classMetadata;

    private final String primaryKeyPropertyName;

    /**
     * Constructor that takes a {@link Class} and a {@link SessionFactory}.
     * 
     * @param clasz a {@link Class}.
     * @param sessionFactory a {@link SessionFactory}. It cannot be null.
     */
    @SuppressWarnings("unchecked")
    public BaseHibernateDAO(SessionFactory sessionFactory) {
        this(null, sessionFactory);
    }

    /**
     * Constructor that takes a {@link Class} and a {@link SessionFactory}.
     * 
     * @param clasz a {@link Class}.
     * @param sessionFactory a {@link SessionFactory}. It cannot be null.
     */
    @SuppressWarnings("unchecked")
    public BaseHibernateDAO(Class<T> clasz, SessionFactory sessionFactory) {

        if (sessionFactory == null) {
            throw new IllegalArgumentException("Parameter sessionFactory cannot be null");
        }

        this.sessionFactory = sessionFactory;

        entityClass = clasz != null ? clasz : extractEntityClassFromHierarchy();
        classMetadata = sessionFactory.getClassMetadata(getEntityClass());

        if (getClassMetadata() == null) {
            throw new RuntimeException("Class " + getEntityClass().getName() + " is not mapped");
        }

        primaryKeyPropertyName = getClassMetadata().getIdentifierPropertyName();

        assert getEntityClass() != null;
        assert getClassMetadata() != null;
        assert getPrimaryKeyPropertyName() != null;

    }

    /**
     * @return
     */
    @SuppressWarnings("unchecked")
    private Class<T> extractEntityClassFromHierarchy() {

        final Type genericSuperclass = getClass().getGenericSuperclass();
        final ParameterizedType parameterizedType = ((ParameterizedType) genericSuperclass);
        return (Class<T>) parameterizedType.getActualTypeArguments()[0];

    }

    /**
     * Returns the entity class handled by this DAO.
     * 
     * @return a {@link Class<T>}.
     */
    protected final Class<T> getEntityClass() {
        return entityClass;
    }

    /**
     * Returns a {@link Session}. This implementation returns
     * {@link SessionFactory#getCurrentSession()} and can be overriden if needed.
     * 
     * @return a {@link Session}.
     */
    protected Session getSession() {
        return getSessionFactory().getCurrentSession();
    }

    /**
     * Returns this DAO's {@link SessionFactory}.
     * 
     * @return a {@link SessionFactory}.
     */
    protected final SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    /**
     * Returns the {@link ClassMetadata} for the corresponding entity class.
     * 
     * @return a {@link ClassMetadata}.
     */
    protected final ClassMetadata getClassMetadata() {
        return classMetadata;
    }

    /**
     * Returns the name of the id property.
     * 
     * @return a {@link String}.
     */
    protected String getPrimaryKeyPropertyName() {
        return primaryKeyPropertyName;
    }

}