/*
* Copyright 2002-2009 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.orm.hibernate3;
import java.sql.SQLException;
import org.hibernate.HibernateException;
import org.hibernate.Session;
/**
* Callback interface for Hibernate code. To be used with {@link HibernateTemplate}'s
* execution methods, often as anonymous classes within a method implementation.
* A typical implementation will call <code>Session.load/find/update</code> to perform
* some operations on persistent objects. It can also perform direct JDBC operations
* via Hibernate's <code>Session.connection()</code>, operating on a JDBC Connection.
*
* <p>Note that Hibernate works on unmodified plain Java objects, performing dirty
* detection via copies made at load time. Returned objects can thus be used outside
* of an active Hibernate Session without any hassle, e.g. for display in a web GUI.
* Reassociating such instances with a new Session, e.g. for updates when coming
* back from the GUI, is straightforward, as the instance has kept its identity.
* You should care to reassociate them as early as possible though, to avoid having
* already loaded a version from the database in the same Session.
*
* @author Juergen Hoeller
* @since 1.2
* @see HibernateTemplate
* @see HibernateTransactionManager
*/
public interface HibernateCallback<T> {
/**
* Gets called by <code>HibernateTemplate.execute</code> with an active
* Hibernate <code>Session</code>. Does not need to care about activating
* or closing the <code>Session</code>, or handling transactions.
*
* <p>If called without a thread-bound Hibernate transaction (initiated
* by HibernateTransactionManager), the code will simply get executed on the
* underlying JDBC connection with its transactional semantics. If Hibernate
* is configured to use a JTA-aware DataSource, the JDBC connection and thus
* the callback code will be transactional if a JTA transaction is active.
*
* <p>Allows for returning a result object created within the callback,
* i.e. a domain object or a collection of domain objects.
* A thrown custom RuntimeException is treated as an application exception:
* It gets propagated to the caller of the template.
*
* @param session active Hibernate session
* @return a result object, or <code>null</code> if none
* @throws HibernateException if thrown by the Hibernate API
* @throws SQLException if thrown by Hibernate-exposed JDBC API
* @see HibernateTemplate#execute
* @see HibernateTemplate#executeFind
*/
T doInHibernate(Session session) throws HibernateException, SQLException;
}
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