/*
 * Copyright 2002-2015 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
 *
 *      https://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.orm.hibernate4;

import java.io.Serializable;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.hibernate.Criteria;
import org.hibernate.Filter;
import org.hibernate.FlushMode;
import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.Query;
import org.hibernate.ReplicationMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.criterion.DetachedCriteria;
import org.hibernate.criterion.Example;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.util.Assert;

/**
 * Helper class that simplifies Hibernate data access code. Automatically
 * converts HibernateExceptions into DataAccessExceptions, following the
 * {@code org.springframework.dao} exception hierarchy.
 *
 * <p>The central method is {@code execute}, supporting Hibernate access code
 * implementing the {@link HibernateCallback} interface. It provides Hibernate Session
 * handling such that neither the HibernateCallback implementation nor the calling
 * code needs to explicitly care about retrieving/closing Hibernate Sessions,
 * or handling Session lifecycle exceptions. For typical single step actions,
 * there are various convenience methods (find, load, saveOrUpdate, delete).
 *
 * <p>Can be used within a service implementation via direct instantiation
 * with a SessionFactory reference, or get prepared in an application context
 * and given to services as bean reference. Note: The SessionFactory should
 * always be configured as bean in the application context, in the first case
 * given to the service directly, in the second case to the prepared template.
 *
 * <p><b>NOTE: Hibernate access code can also be coded in plain Hibernate style.
 * Hence, for newly started projects, consider adopting the standard Hibernate
 * style of coding data access objects instead, based on
 * {@link org.hibernate.SessionFactory#getCurrentSession()}.
 * This HibernateTemplate primarily exists as a migration helper for Hibernate 3
 * based data access code, to benefit from bug fixes in Hibernate 4.x.</b>
 *
 * @author Juergen Hoeller
 * @since 4.0.1
 * @see #setSessionFactory
 * @see HibernateCallback
 * @see org.hibernate.Session
 * @see LocalSessionFactoryBean
 * @see HibernateTransactionManager
 * @see org.springframework.orm.hibernate4.support.OpenSessionInViewFilter
 * @see org.springframework.orm.hibernate4.support.OpenSessionInViewInterceptor
 */
public class HibernateTemplate implements HibernateOperations, InitializingBean {

        protected final Log logger = LogFactory.getLog(getClass());

        private SessionFactory sessionFactory;

        private String[] filterNames;

        private boolean exposeNativeSession = false;

        private boolean checkWriteOperations = true;

        private boolean cacheQueries = false;

        private String queryCacheRegion;

        private int fetchSize = 0;

        private int maxResults = 0;


        /**
         * Create a new HibernateTemplate instance.
         */
        public HibernateTemplate() {
        }

        /**
         * Create a new HibernateTemplate instance.
         * @param sessionFactory the SessionFactory to create Sessions with
         */
        public HibernateTemplate(SessionFactory sessionFactory) {
                setSessionFactory(sessionFactory);
                afterPropertiesSet();
        }


        /**
         * Set the Hibernate SessionFactory that should be used to create
         * Hibernate Sessions.
         */
        public void setSessionFactory(SessionFactory sessionFactory) {
                this.sessionFactory = sessionFactory;
        }

        /**
         * Return the Hibernate SessionFactory that should be used to create
         * Hibernate Sessions.
         */
        public SessionFactory getSessionFactory() {
                return this.sessionFactory;
        }

        /**
         * Set one or more names of Hibernate filters to be activated for all
         * Sessions that this accessor works with.
         * <p>Each of those filters will be enabled at the beginning of each
         * operation and correspondingly disabled at the end of the operation.
         * This will work for newly opened Sessions as well as for existing
         * Sessions (for example, within a transaction).
         * @see #enableFilters(org.hibernate.Session)
         * @see org.hibernate.Session#enableFilter(String)
         */
        public void setFilterNames(String... filterNames) {
                this.filterNames = filterNames;
        }

        /**
         * Return the names of Hibernate filters to be activated, if any.
         */
        public String[] getFilterNames() {
                return this.filterNames;
        }

        /**
         * Set whether to expose the native Hibernate Session to
         * HibernateCallback code.
         * <p>Default is "false": a Session proxy will be returned, suppressing
         * {@code close} calls and automatically applying query cache
         * settings and transaction timeouts.
         * @see HibernateCallback
         * @see org.hibernate.Session
         * @see #setCacheQueries
         * @see #setQueryCacheRegion
         * @see #prepareQuery
         * @see #prepareCriteria
         */
        public void setExposeNativeSession(boolean exposeNativeSession) {
                this.exposeNativeSession = exposeNativeSession;
        }

        /**
         * Return whether to expose the native Hibernate Session to
         * HibernateCallback code, or rather a Session proxy.
         */
        public boolean isExposeNativeSession() {
                return this.exposeNativeSession;
        }

        /**
         * Set whether to check that the Hibernate Session is not in read-only mode
         * in case of write operations (save/update/delete).
         * <p>Default is "true", for fail-fast behavior when attempting write operations
         * within a read-only transaction. Turn this off to allow save/update/delete
         * on a Session with flush mode MANUAL.
         * @see #checkWriteOperationAllowed
         * @see org.springframework.transaction.TransactionDefinition#isReadOnly
         */
        public void setCheckWriteOperations(boolean checkWriteOperations) {
                this.checkWriteOperations = checkWriteOperations;
        }

        /**
         * Return whether to check that the Hibernate Session is not in read-only
         * mode in case of write operations (save/update/delete).
         */
        public boolean isCheckWriteOperations() {
                return this.checkWriteOperations;
        }

        /**
         * Set whether to cache all queries executed by this template.
         * <p>If this is "true", all Query and Criteria objects created by
         * this template will be marked as cacheable (including all
         * queries through find methods).
         * <p>To specify the query region to be used for queries cached
         * by this template, set the "queryCacheRegion" property.
         * @see #setQueryCacheRegion
         * @see org.hibernate.Query#setCacheable
         * @see org.hibernate.Criteria#setCacheable
         */
        public void setCacheQueries(boolean cacheQueries) {
                this.cacheQueries = cacheQueries;
        }

        /**
         * Return whether to cache all queries executed by this template.
         */
        public boolean isCacheQueries() {
                return this.cacheQueries;
        }

        /**
         * Set the name of the cache region for queries executed by this template.
         * <p>If this is specified, it will be applied to all Query and Criteria objects
         * created by this template (including all queries through find methods).
         * <p>The cache region will not take effect unless queries created by this
         * template are configured to be cached via the "cacheQueries" property.
         * @see #setCacheQueries
         * @see org.hibernate.Query#setCacheRegion
         * @see org.hibernate.Criteria#setCacheRegion
         */
        public void setQueryCacheRegion(String queryCacheRegion) {
                this.queryCacheRegion = queryCacheRegion;
        }

        /**
         * Return the name of the cache region for queries executed by this template.
         */
        public String getQueryCacheRegion() {
                return this.queryCacheRegion;
        }

        /**
         * Set the fetch size for this HibernateTemplate. This is important for processing
         * large result sets: Setting this higher than the default value will increase
         * processing speed at the cost of memory consumption; setting this lower can
         * avoid transferring row data that will never be read by the application.
         * <p>Default is 0, indicating to use the JDBC driver's default.
         */
        public void setFetchSize(int fetchSize) {
                this.fetchSize = fetchSize;
        }

        /**
         * Return the fetch size specified for this HibernateTemplate.
         */
        public int getFetchSize() {
                return this.fetchSize;
        }

        /**
         * Set the maximum number of rows for this HibernateTemplate. This is important
         * for processing subsets of large result sets, avoiding to read and hold
         * the entire result set in the database or in the JDBC driver if we're
         * never interested in the entire result in the first place (for example,
         * when performing searches that might return a large number of matches).
         * <p>Default is 0, indicating to use the JDBC driver's default.
         */
        public void setMaxResults(int maxResults) {
                this.maxResults = maxResults;
        }

        /**
         * Return the maximum number of rows specified for this HibernateTemplate.
         */
        public int getMaxResults() {
                return this.maxResults;
        }

        @Override
        public void afterPropertiesSet() {
                if (getSessionFactory() == null) {
                        throw new IllegalArgumentException("Property 'sessionFactory' is required");
                }
        }


        @Override
        public <T> T execute(HibernateCallback<T> action) throws DataAccessException {
                return doExecute(action, false);
        }

        /**
         * Execute the action specified by the given action object within a
         * native {@link org.hibernate.Session}.
         * <p>This execute variant overrides the template-wide
         * {@link #isExposeNativeSession() "exposeNativeSession"} setting.
         * @param action callback object that specifies the Hibernate action
         * @return a result object returned by the action, or {@code null}
         * @throws org.springframework.dao.DataAccessException in case of Hibernate errors
         */
        public <T> T executeWithNativeSession(HibernateCallback<T> action) {
                return doExecute(action, true);
        }

        /**
         * Execute the action specified by the given action object within a Session.
         * @param action callback object that specifies the Hibernate action
         * @param enforceNativeSession whether to enforce exposure of the native
         * Hibernate Session to callback code
         * @return a result object returned by the action, or {@code null}
         * @throws org.springframework.dao.DataAccessException in case of Hibernate errors
         */
        protected <T> T doExecute(HibernateCallback<T> action, boolean enforceNativeSession) throws DataAccessException {
                Assert.notNull(action, "Callback object must not be null");

                Session session = null;
                boolean isNew = false;
                try {
                        session = getSessionFactory().getCurrentSession();
                }
                catch (HibernateException ex) {
                        logger.debug("Could not retrieve pre-bound Hibernate session", ex);
                }
                if (session == null) {
                        session = getSessionFactory().openSession();
                        session.setFlushMode(FlushMode.MANUAL);
                        isNew = true;
                }

                try {
                        enableFilters(session);
                        Session sessionToExpose =
                                        (enforceNativeSession || isExposeNativeSession() ? session : createSessionProxy(session));
                        return action.doInHibernate(sessionToExpose);
                }
                catch (HibernateException ex) {
                        throw SessionFactoryUtils.convertHibernateAccessException(ex);
                }
                catch (RuntimeException ex) {
                        // Callback code threw application exception...
                        throw ex;
                }
                finally {
                        if (isNew) {
                                SessionFactoryUtils.closeSession(session);
                        }
                        else {
                                disableFilters(session);
                        }
                }
        }

        /**
         * Create a close-suppressing proxy for the given Hibernate Session.
         * The proxy also prepares returned Query and Criteria objects.
         * @param session the Hibernate Session to create a proxy for
         * @return the Session proxy
         * @see org.hibernate.Session#close()
         * @see #prepareQuery
         * @see #prepareCriteria
         */
        protected Session createSessionProxy(Session session) {
                return (Session) Proxy.newProxyInstance(
                                session.getClass().getClassLoader(), new Class<?>[] {Session.class},
                                new CloseSuppressingInvocationHandler(session));
        }

        /**
         * Enable the specified filters on the given Session.
         * @param session the current Hibernate Session
         * @see #setFilterNames
         * @see org.hibernate.Session#enableFilter(String)
         */
        protected void enableFilters(Session session) {
                String[] filterNames = getFilterNames();
                if (filterNames != null) {
                        for (String filterName : filterNames) {
                                session.enableFilter(filterName);
                        }
                }
        }

        /**
         * Disable the specified filters on the given Session.
         * @param session the current Hibernate Session
         * @see #setFilterNames
         * @see org.hibernate.Session#disableFilter(String)
         */
        protected void disableFilters(Session session) {
                String[] filterNames = getFilterNames();
                if (filterNames != null) {
                        for (String filterName : filterNames) {
                                session.disableFilter(filterName);
                        }
                }
        }


        //-------------------------------------------------------------------------
        // Convenience methods for loading individual objects
        //-------------------------------------------------------------------------

        @Override
        public <T> T get(Class<T> entityClass, Serializable id) throws DataAccessException {
                return get(entityClass, id, null);
        }

        @Override
        public <T> T get(final Class<T> entityClass, final Serializable id, final LockMode lockMode)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<T>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public T doInHibernate(Session session) throws HibernateException {
                                if (lockMode != null) {
                                        return (T) session.get(entityClass, id, new LockOptions(lockMode));
                                }
                                else {
                                        return (T) session.get(entityClass, id);
                                }
                        }
                });
        }

        @Override
        public Object get(String entityName, Serializable id) throws DataAccessException {
                return get(entityName, id, null);
        }

        @Override
        public Object get(final String entityName, final Serializable id, final LockMode lockMode)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                if (lockMode != null) {
                                        return session.get(entityName, id, new LockOptions(lockMode));
                                }
                                else {
                                        return session.get(entityName, id);
                                }
                        }
                });
        }

        @Override
        public <T> T load(Class<T> entityClass, Serializable id) throws DataAccessException {
                return load(entityClass, id, null);
        }

        @Override
        public <T> T load(final Class<T> entityClass, final Serializable id, final LockMode lockMode)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<T>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public T doInHibernate(Session session) throws HibernateException {
                                if (lockMode != null) {
                                        return (T) session.load(entityClass, id, new LockOptions(lockMode));
                                }
                                else {
                                        return (T) session.load(entityClass, id);
                                }
                        }
                });
        }

        @Override
        public Object load(String entityName, Serializable id) throws DataAccessException {
                return load(entityName, id, null);
        }

        @Override
        public Object load(final String entityName, final Serializable id, final LockMode lockMode)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                if (lockMode != null) {
                                        return session.load(entityName, id, new LockOptions(lockMode));
                                }
                                else {
                                        return session.load(entityName, id);
                                }
                        }
                });
        }

        @Override
        public <T> List<T> loadAll(final Class<T> entityClass) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<List<T>>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public List<T> doInHibernate(Session session) throws HibernateException {
                                Criteria criteria = session.createCriteria(entityClass);
                                criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
                                prepareCriteria(criteria);
                                return criteria.list();
                        }
                });
        }

        @Override
        public void load(final Object entity, final Serializable id) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                session.load(entity, id);
                                return null;
                        }
                });
        }

        @Override
        public void refresh(final Object entity) throws DataAccessException {
                refresh(entity, null);
        }

        @Override
        public void refresh(final Object entity, final LockMode lockMode) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                if (lockMode != null) {
                                        session.refresh(entity, new LockOptions(lockMode));
                                }
                                else {
                                        session.refresh(entity);
                                }
                                return null;
                        }
                });
        }

        @Override
        public boolean contains(final Object entity) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<Boolean>() {
                        @Override
                        public Boolean doInHibernate(Session session) {
                                return session.contains(entity);
                        }
                });
        }

        @Override
        public void evict(final Object entity) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                session.evict(entity);
                                return null;
                        }
                });
        }

        @Override
        public void initialize(Object proxy) throws DataAccessException {
                try {
                        Hibernate.initialize(proxy);
                }
                catch (HibernateException ex) {
                        throw SessionFactoryUtils.convertHibernateAccessException(ex);
                }
        }

        @Override
        public Filter enableFilter(String filterName) throws IllegalStateException {
                Session session = getSessionFactory().getCurrentSession();
                Filter filter = session.getEnabledFilter(filterName);
                if (filter == null) {
                        filter = session.enableFilter(filterName);
                }
                return filter;
        }


        //-------------------------------------------------------------------------
        // Convenience methods for storing individual objects
        //-------------------------------------------------------------------------

        @Override
        public void lock(final Object entity, final LockMode lockMode) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                session.buildLockRequest(new LockOptions(lockMode)).lock(entity);
                                return null;
                        }
                });
        }

        @Override
        public void lock(final String entityName, final Object entity, final LockMode lockMode)
                        throws DataAccessException {

                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                session.buildLockRequest(new LockOptions(lockMode)).lock(entityName, entity);
                                return null;
                        }
                });
        }

        @Override
        public Serializable save(final Object entity) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<Serializable>() {
                        @Override
                        public Serializable doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                return session.save(entity);
                        }
                });
        }

        @Override
        public Serializable save(final String entityName, final Object entity) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<Serializable>() {
                        @Override
                        public Serializable doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                return session.save(entityName, entity);
                        }
                });
        }

        @Override
        public void update(Object entity) throws DataAccessException {
                update(entity, null);
        }

        @Override
        public void update(final Object entity, final LockMode lockMode) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.update(entity);
                                if (lockMode != null) {
                                        session.buildLockRequest(new LockOptions(lockMode)).lock(entity);
                                }
                                return null;
                        }
                });
        }

        @Override
        public void update(String entityName, Object entity) throws DataAccessException {
                update(entityName, entity, null);
        }

        @Override
        public void update(final String entityName, final Object entity, final LockMode lockMode)
                        throws DataAccessException {

                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.update(entityName, entity);
                                if (lockMode != null) {
                                        session.buildLockRequest(new LockOptions(lockMode)).lock(entityName, entity);
                                }
                                return null;
                        }
                });
        }

        @Override
        public void saveOrUpdate(final Object entity) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.saveOrUpdate(entity);
                                return null;
                        }
                });
        }

        @Override
        public void saveOrUpdate(final String entityName, final Object entity) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.saveOrUpdate(entityName, entity);
                                return null;
                        }
                });
        }

        @Override
        public void replicate(final Object entity, final ReplicationMode replicationMode)
                        throws DataAccessException {

                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.replicate(entity, replicationMode);
                                return null;
                        }
                });
        }

        @Override
        public void replicate(final String entityName, final Object entity, final ReplicationMode replicationMode)
                        throws DataAccessException {

                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.replicate(entityName, entity, replicationMode);
                                return null;
                        }
                });
        }

        @Override
        public void persist(final Object entity) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.persist(entity);
                                return null;
                        }
                });
        }

        @Override
        public void persist(final String entityName, final Object entity) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                session.persist(entityName, entity);
                                return null;
                        }
                });
        }

        @Override
        public <T> T merge(final T entity) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<T>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public T doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                return (T) session.merge(entity);
                        }
                });
        }

        @Override
        public <T> T merge(final String entityName, final T entity) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<T>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public T doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                return (T) session.merge(entityName, entity);
                        }
                });
        }

        @Override
        public void delete(Object entity) throws DataAccessException {
                delete(entity, null);
        }

        @Override
        public void delete(final Object entity, final LockMode lockMode) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                if (lockMode != null) {
                                        session.buildLockRequest(new LockOptions(lockMode)).lock(entity);
                                }
                                session.delete(entity);
                                return null;
                        }
                });
        }

        @Override
        public void delete(String entityName, Object entity) throws DataAccessException {
                delete(entityName, entity, null);
        }

        @Override
        public void delete(final String entityName, final Object entity, final LockMode lockMode)
                        throws DataAccessException {

                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                if (lockMode != null) {
                                        session.buildLockRequest(new LockOptions(lockMode)).lock(entityName, entity);
                                }
                                session.delete(entityName, entity);
                                return null;
                        }
                });
        }

        @Override
        public void deleteAll(final Collection<?> entities) throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                checkWriteOperationAllowed(session);
                                for (Object entity : entities) {
                                        session.delete(entity);
                                }
                                return null;
                        }
                });
        }

        @Override
        public void flush() throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) throws HibernateException {
                                session.flush();
                                return null;
                        }
                });
        }

        @Override
        public void clear() throws DataAccessException {
                executeWithNativeSession(new HibernateCallback<Object>() {
                        @Override
                        public Object doInHibernate(Session session) {
                                session.clear();
                                return null;
                        }
                });
        }


        //-------------------------------------------------------------------------
        // Convenience finder methods for HQL strings
        //-------------------------------------------------------------------------

        @Override
        public List<?> find(final String queryString, final Object... values) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.createQuery(queryString);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                queryObject.setParameter(i, values[i]);
                                        }
                                }
                                return queryObject.list();
                        }
                });
        }

        @Override
        public List<?> findByNamedParam(String queryString, String paramName, Object value)
                        throws DataAccessException {

                return findByNamedParam(queryString, new String[] {paramName}, new Object[] {value});
        }

        @Override
        public List<?> findByNamedParam(final String queryString, final String[] paramNames, final Object[] values)
                        throws DataAccessException {

                if (paramNames.length != values.length) {
                        throw new IllegalArgumentException("Length of paramNames array must match length of values array");
                }
                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.createQuery(queryString);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                applyNamedParameterToQuery(queryObject, paramNames[i], values[i]);
                                        }
                                }
                                return queryObject.list();
                        }
                });
        }

        @Override
        public List<?> findByValueBean(final String queryString, final Object valueBean)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.createQuery(queryString);
                                prepareQuery(queryObject);
                                queryObject.setProperties(valueBean);
                                return queryObject.list();
                        }
                });
        }


        //-------------------------------------------------------------------------
        // Convenience finder methods for named queries
        //-------------------------------------------------------------------------

        @Override
        public List<?> findByNamedQuery(final String queryName, final Object... values) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.getNamedQuery(queryName);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                queryObject.setParameter(i, values[i]);
                                        }
                                }
                                return queryObject.list();
                        }
                });
        }

        @Override
        public List<?> findByNamedQueryAndNamedParam(String queryName, String paramName, Object value)
                        throws DataAccessException {

                return findByNamedQueryAndNamedParam(queryName, new String[] {paramName}, new Object[] {value});
        }

        @Override
        public List<?> findByNamedQueryAndNamedParam(
                        final String queryName, final String[] paramNames, final Object[] values)
                        throws DataAccessException {

                if (values != null && (paramNames == null || paramNames.length != values.length)) {
                        throw new IllegalArgumentException("Length of paramNames array must match length of values array");
                }
                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.getNamedQuery(queryName);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                applyNamedParameterToQuery(queryObject, paramNames[i], values[i]);
                                        }
                                }
                                return queryObject.list();
                        }
                });
        }

        @Override
        public List<?> findByNamedQueryAndValueBean(final String queryName, final Object valueBean)
                        throws DataAccessException {

                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.getNamedQuery(queryName);
                                prepareQuery(queryObject);
                                queryObject.setProperties(valueBean);
                                return queryObject.list();
                        }
                });
        }


        //-------------------------------------------------------------------------
        // Convenience finder methods for detached criteria
        //-------------------------------------------------------------------------

        @Override
        public List<?> findByCriteria(DetachedCriteria criteria) throws DataAccessException {
                return findByCriteria(criteria, -1, -1);
        }

        @Override
        public List<?> findByCriteria(final DetachedCriteria criteria, final int firstResult, final int maxResults)
                        throws DataAccessException {

                Assert.notNull(criteria, "DetachedCriteria must not be null");
                return executeWithNativeSession(new HibernateCallback<List<?>>() {
                        @Override
                        public List<?> doInHibernate(Session session) throws HibernateException {
                                Criteria executableCriteria = criteria.getExecutableCriteria(session);
                                prepareCriteria(executableCriteria);
                                if (firstResult >= 0) {
                                        executableCriteria.setFirstResult(firstResult);
                                }
                                if (maxResults > 0) {
                                        executableCriteria.setMaxResults(maxResults);
                                }
                                return executableCriteria.list();
                        }
                });
        }

        @Override
        public <T> List<T> findByExample(T exampleEntity) throws DataAccessException {
                return findByExample(null, exampleEntity, -1, -1);
        }

        @Override
        public <T> List<T> findByExample(String entityName, T exampleEntity) throws DataAccessException {
                return findByExample(entityName, exampleEntity, -1, -1);
        }

        @Override
        public <T> List<T> findByExample(T exampleEntity, int firstResult, int maxResults) throws DataAccessException {
                return findByExample(null, exampleEntity, firstResult, maxResults);
        }

        @Override
        public <T> List<T> findByExample(
                        final String entityName, final T exampleEntity, final int firstResult, final int maxResults)
                        throws DataAccessException {

                Assert.notNull(exampleEntity, "Example entity must not be null");
                return executeWithNativeSession(new HibernateCallback<List<T>>() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public List<T> doInHibernate(Session session) throws HibernateException {
                                Criteria executableCriteria = (entityName != null ?
                                                session.createCriteria(entityName) : session.createCriteria(exampleEntity.getClass()));
                                executableCriteria.add(Example.create(exampleEntity));
                                prepareCriteria(executableCriteria);
                                if (firstResult >= 0) {
                                        executableCriteria.setFirstResult(firstResult);
                                }
                                if (maxResults > 0) {
                                        executableCriteria.setMaxResults(maxResults);
                                }
                                return executableCriteria.list();
                        }
                });
        }


        //-------------------------------------------------------------------------
        // Convenience query methods for iteration and bulk updates/deletes
        //-------------------------------------------------------------------------

        @Override
        public Iterator<?> iterate(final String queryString, final Object... values) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<Iterator<?>>() {
                        @Override
                        public Iterator<?> doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.createQuery(queryString);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                queryObject.setParameter(i, values[i]);
                                        }
                                }
                                return queryObject.iterate();
                        }
                });
        }

        @Override
        public void closeIterator(Iterator<?> it) throws DataAccessException {
                try {
                        Hibernate.close(it);
                }
                catch (HibernateException ex) {
                        throw SessionFactoryUtils.convertHibernateAccessException(ex);
                }
        }

        @Override
        public int bulkUpdate(final String queryString, final Object... values) throws DataAccessException {
                return executeWithNativeSession(new HibernateCallback<Integer>() {
                        @Override
                        public Integer doInHibernate(Session session) throws HibernateException {
                                Query queryObject = session.createQuery(queryString);
                                prepareQuery(queryObject);
                                if (values != null) {
                                        for (int i = 0; i < values.length; i++) {
                                                queryObject.setParameter(i, values[i]);
                                        }
                                }
                                return queryObject.executeUpdate();
                        }
                });
        }


        //-------------------------------------------------------------------------
        // Helper methods used by the operations above
        //-------------------------------------------------------------------------

        /**
         * Check whether write operations are allowed on the given Session.
         * <p>Default implementation throws an InvalidDataAccessApiUsageException in
         * case of {@code FlushMode.MANUAL}. Can be overridden in subclasses.
         * @param session current Hibernate Session
         * @throws InvalidDataAccessApiUsageException if write operations are not allowed
         * @see #setCheckWriteOperations
         * @see org.hibernate.Session#getFlushMode()
         * @see org.hibernate.FlushMode#MANUAL
         */
        protected void checkWriteOperationAllowed(Session session) throws InvalidDataAccessApiUsageException {
                if (isCheckWriteOperations() && session.getFlushMode().lessThan(FlushMode.COMMIT)) {
                        throw new InvalidDataAccessApiUsageException(
                                        "Write operations are not allowed in read-only mode (FlushMode.MANUAL): "+
                                        "Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction definition.");
                }
        }

        /**
         * Prepare the given Query object, applying cache settings and/or
         * a transaction timeout.
         * @param queryObject the Query object to prepare
         * @see #setCacheQueries
         * @see #setQueryCacheRegion
         */
        protected void prepareQuery(Query queryObject) {
                if (isCacheQueries()) {
                        queryObject.setCacheable(true);
                        if (getQueryCacheRegion() != null) {
                                queryObject.setCacheRegion(getQueryCacheRegion());
                        }
                }
                if (getFetchSize() > 0) {
                        queryObject.setFetchSize(getFetchSize());
                }
                if (getMaxResults() > 0) {
                        queryObject.setMaxResults(getMaxResults());
                }

                SessionHolder sessionHolder =
                                (SessionHolder) TransactionSynchronizationManager.getResource(getSessionFactory());
                if (sessionHolder != null && sessionHolder.hasTimeout()) {
                        queryObject.setTimeout(sessionHolder.getTimeToLiveInSeconds());
                }
        }

        /**
         * Prepare the given Criteria object, applying cache settings and/or
         * a transaction timeout.
         * @param criteria the Criteria object to prepare
         * @see #setCacheQueries
         * @see #setQueryCacheRegion
         */
        protected void prepareCriteria(Criteria criteria) {
                if (isCacheQueries()) {
                        criteria.setCacheable(true);
                        if (getQueryCacheRegion() != null) {
                                criteria.setCacheRegion(getQueryCacheRegion());
                        }
                }
                if (getFetchSize() > 0) {
                        criteria.setFetchSize(getFetchSize());
                }
                if (getMaxResults() > 0) {
                        criteria.setMaxResults(getMaxResults());
                }

                SessionHolder sessionHolder =
                                (SessionHolder) TransactionSynchronizationManager.getResource(getSessionFactory());
                if (sessionHolder != null && sessionHolder.hasTimeout()) {
                        criteria.setTimeout(sessionHolder.getTimeToLiveInSeconds());
                }
        }

        /**
         * Apply the given name parameter to the given Query object.
         * @param queryObject the Query object
         * @param paramName the name of the parameter
         * @param value the value of the parameter
         * @throws HibernateException if thrown by the Query object
         */
        protected void applyNamedParameterToQuery(Query queryObject, String paramName, Object value)
                        throws HibernateException {

                if (value instanceof Collection) {
                        queryObject.setParameterList(paramName, (Collection<?>) value);
                }
                else if (value instanceof Object[]) {
                        queryObject.setParameterList(paramName, (Object[]) value);
                }
                else {
                        queryObject.setParameter(paramName, value);
                }
        }


        /**
         * Invocation handler that suppresses close calls on Hibernate Sessions.
         * Also prepares returned Query and Criteria objects.
         * @see org.hibernate.Session#close
         */
        private class CloseSuppressingInvocationHandler implements InvocationHandler {

                private final Session target;

                public CloseSuppressingInvocationHandler(Session target) {
                        this.target = target;
                }

                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        // Invocation on Session interface coming in...

                        if (method.getName().equals("equals")) {
                                // Only consider equal when proxies are identical.
                                return (proxy == args[0]);
                        }
                        else if (method.getName().equals("hashCode")) {
                                // Use hashCode of Session proxy.
                                return System.identityHashCode(proxy);
                        }
                        else if (method.getName().equals("close")) {
                                // Handle close method: suppress, not valid.
                                return null;
                        }

                        // Invoke method on target Session.
                        try {
                                Object retVal = method.invoke(this.target, args);

                                // If return value is a Query or Criteria, apply transaction timeout.
                                // Applies to createQuery, getNamedQuery, createCriteria.
                                if (retVal instanceof Query) {
                                        prepareQuery(((Query) retVal));
                                }
                                if (retVal instanceof Criteria) {
                                        prepareCriteria(((Criteria) retVal));
                                }

                                return retVal;
                        }
                        catch (InvocationTargetException ex) {
                                throw ex.getTargetException();
                        }
                }
        }

}