Java tutorial
/*************************************************************************** * Copyright (c) 2012-2013 VMware, Inc. All Rights Reserved. * 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 com.vmware.bdd.dal.impl; import java.io.Serializable; import java.lang.reflect.ParameterizedType; import java.util.List; import org.apache.log4j.Logger; import org.hibernate.Criteria; import org.hibernate.HibernateException; import org.hibernate.SessionFactory; import org.hibernate.criterion.Criterion; import org.hibernate.criterion.Order; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.transaction.annotation.Transactional; import com.vmware.bdd.dal.IBaseDAO; import com.vmware.bdd.utils.AuAssert; /** * @author Jarred Li * @since 0.8 * @version 0.8 * */ public abstract class BaseDAO<T> implements IBaseDAO<T> { private static final Logger logger = Logger.getLogger(BaseDAO.class); protected SessionFactory sessionFactory; private final Class<T> type; @SuppressWarnings("unchecked") public BaseDAO() { this.type = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0]; } /** * @return the sessionFactory */ public SessionFactory getSessionFactory() { return sessionFactory; } /** * @param sessionFactory * the sessionFactory to set */ @Autowired public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } /* (non-Javadoc) * @see com.vmware.bdd.dal.IBaseDAO#insert(T) */ @Override @Transactional public void insert(T object) { this.getSessionFactory().getCurrentSession().save(object); } /* (non-Javadoc) * @see com.vmware.bdd.dal.IBaseDAO#delete(T) */ @Override @Transactional public void delete(T object) { this.sessionFactory.getCurrentSession().delete(object); } /* (non-Javadoc) * @see com.vmware.bdd.dal.IBaseDAO#update(T) */ @Override @Transactional public void update(T object) { this.sessionFactory.getCurrentSession().update(object); } /* (non-Javadoc) * @see com.vmware.bdd.dal.IBaseDAO#findAll() */ @Override @SuppressWarnings("unchecked") @Transactional(readOnly = true) public List<T> findAll() { logger.debug("findAll"); List<T> result = null; Criteria query = this.sessionFactory.getCurrentSession().createCriteria(type); result = query.list(); return result; } /* (non-Javadoc) * @see com.vmware.bdd.dal.IBaseDAO#findById(java.io.Serializable) */ @Override @SuppressWarnings("unchecked") @Transactional(readOnly = true) public T findById(Serializable id) { return (T) this.sessionFactory.getCurrentSession().get(type, id); } /** * Fetch and return a list of objects of the given class that satisfy the * given criteria. * * @param queryCriteria * -- the criteria to filter the results. * @return The list of matching objects. * @throws HibernateException * -- on Hibernate errors. **/ @Override @Transactional(readOnly = true) public List<T> findByCriteria(final Criterion... queryCriteria) { return findByCriteria(null, null, null, queryCriteria); } /** * Fetch and return an object that satisfies the given criteria. * * @param queryCriteria * -- the criteria to filter the results. * @return The matching object or null if the object is not found. If the * object is not unique, an assertion is thrown. **/ @Override @Transactional(readOnly = true) public T findUniqueByCriteria(Criterion... queryCriteria) { List<T> results = findByCriteria(queryCriteria); if (results.size() == 0) { return null; } else { AuAssert.check(results.size() == 1); return results.get(0); } } /** * Fetch and return a list of objects of the given class which is a subset of * the all the records that satisfy the given criteria. The subset is * specified by parameter firstResult and maxResults. * * @param order * -- the result set order. * @param firstResult * -- the offset in the query result where the returned list * starts. * @param maxResults * -- the maximum records returned. * @param queryCriteria * -- the criteria to filter the results. * @return The list of matching objects. * @throws HibernateException * -- on Hibernate errors. */ @SuppressWarnings("unchecked") protected List<T> findByCriteria(final Order[] order, final Integer firstResult, final Integer maxResults, final Criterion... queryCriteria) { Criteria criteria = sessionFactory.getCurrentSession().createCriteria(type); for (Criterion c : queryCriteria) { criteria.add(c); } if (order != null) { for (Order o : order) { criteria.addOrder(o); } } if (firstResult != null) { criteria.setFirstResult(firstResult); } if (maxResults != null) { criteria.setMaxResults(maxResults); criteria.setFetchSize(maxResults); // just a hint } return criteria.list(); } }