/*
* Copyright 2006-2013 the original author or authors.
*
* 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 org.springframework.batch.item.database;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import org.hibernate.query.Query;
import org.hibernate.ScrollMode;
import org.hibernate.ScrollableResults;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.StatelessSession;
import org.springframework.batch.item.database.orm.HibernateQueryProvider;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;
/**
* Internal shared state helper for hibernate readers managing sessions and
* queries.
*
* @author Dave Syer
*
*/
@SuppressWarnings("rawtype")
public class HibernateItemReaderHelper<T> implements InitializingBean {
private SessionFactory sessionFactory;
private String queryString = "";
private String queryName = "";
private HibernateQueryProvider<? extends T> queryProvider;
private boolean useStatelessSession = true;
private StatelessSession statelessSession;
private Session statefulSession;
/**
* @param queryName name of a hibernate named query
*/
public void setQueryName(String queryName) {
this.queryName = queryName;
}
/**
* @param queryString HQL query string
*/
public void setQueryString(String queryString) {
this.queryString = queryString;
}
/**
* @param queryProvider Hibernate query provider
*/
public void setQueryProvider(HibernateQueryProvider<? extends T> queryProvider) {
this.queryProvider = queryProvider;
}
/**
* Can be set only in uninitialized state.
*
* @param useStatelessSession <code>true</code> to use
* {@link StatelessSession} <code>false</code> to use standard hibernate
* {@link Session}
*/
public void setUseStatelessSession(boolean useStatelessSession) {
Assert.state(statefulSession == null && statelessSession == null,
"The useStatelessSession flag can only be set before a session is initialized.");
this.useStatelessSession = useStatelessSession;
}
/**
* @param sessionFactory hibernate session factory
*/
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
@Override
public void afterPropertiesSet() throws Exception {
Assert.state(sessionFactory != null, "A SessionFactory must be provided");
if (queryProvider == null) {
Assert.notNull(sessionFactory, "session factory must be set");
Assert.state(StringUtils.hasText(queryString) ^ StringUtils.hasText(queryName),
"queryString or queryName must be set");
}
}
/**
* Get a cursor over all of the results, with the forward-only flag set.
*
* @param fetchSize the fetch size to use retrieving the results
* @param parameterValues the parameter values to use (or null if none).
*
* @return a forward-only {@link ScrollableResults}
*/
public ScrollableResults getForwardOnlyCursor(int fetchSize, Map<String, Object> parameterValues) {
Query query = createQuery();
if (parameterValues != null) {
query.setProperties(parameterValues);
}
return query.setFetchSize(fetchSize).scroll(ScrollMode.FORWARD_ONLY);
}
/**
* Open appropriate type of hibernate session and create the query.
*
* @return a Hibernate Query
*/
public Query createQuery() {
if (useStatelessSession) {
if (statelessSession == null) {
statelessSession = sessionFactory.openStatelessSession();
}
if (queryProvider != null) {
queryProvider.setStatelessSession(statelessSession);
}
else {
if (StringUtils.hasText(queryName)) {
return statelessSession.getNamedQuery(queryName);
}
else {
return statelessSession.createQuery(queryString);
}
}
}
else {
if (statefulSession == null) {
statefulSession = sessionFactory.openSession();
}
if (queryProvider != null) {
queryProvider.setSession(statefulSession);
}
else {
if (StringUtils.hasText(queryName)) {
return statefulSession.getNamedQuery(queryName);
}
else {
return statefulSession.createQuery(queryString);
}
}
}
// If queryProvider is set use it to create a query
return queryProvider.createQuery();
}
/**
* Scroll through the results up to the item specified.
*
* @param cursor the results to scroll over
* @param itemIndex index to scroll to
* @param flushInterval the number of items to scroll past before flushing
*/
public void jumpToItem(ScrollableResults cursor, int itemIndex, int flushInterval) {
for (int i = 0; i < itemIndex; i++) {
cursor.next();
if (i % flushInterval == 0 && !useStatelessSession) {
statefulSession.clear(); // Clears in-memory cache
}
}
}
/**
* Close the open session (stateful or otherwise).
*/
public void close() {
if (statelessSession != null) {
statelessSession.close();
statelessSession = null;
}
if (statefulSession != null) {
Method close = ReflectionUtils.findMethod(Session.class, "close");
ReflectionUtils.invokeMethod(close, statefulSession);
statefulSession = null;
}
}
/**
* Read a page of data, clearing the existing session (if necessary) first,
* and creating a new session before executing the query.
*
* @param page the page to read (starting at 0)
* @param pageSize the size of the page or maximum number of items to read
* @param fetchSize the fetch size to use
* @param parameterValues the parameter values to use (if any, otherwise
* null)
* @return a collection of items
*/
public Collection<? extends T> readPage(int page, int pageSize, int fetchSize, Map<String, Object> parameterValues) {
clear();
Query query = createQuery();
if (parameterValues != null) {
query.setProperties(parameterValues);
}
@SuppressWarnings("unchecked")
List<T> result = query.setFetchSize(fetchSize).setFirstResult(page * pageSize).setMaxResults(pageSize).list();
return result;
}
/**
* Clear the session if stateful.
*/
public void clear() {
if (statefulSession != null) {
statefulSession.clear();
}
}
}