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Spring Framework example source code file (TopLinkJpaDialect.java)

This example Spring Framework source code file (TopLinkJpaDialect.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

abstractsession, connectionhandle, jdbc, object, override, override, persistenceexception, persistenceexception, sql, sqlexception, sqlexception, toplinkjpadialect, transactiondefinition, transactionexception, unitofwork, unitofwork

The Spring Framework TopLinkJpaDialect.java source code

/*
 * Copyright 2002-2008 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.jpa.vendor;

import java.sql.Connection;
import java.sql.SQLException;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;

import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.sessions.Session;
import oracle.toplink.essentials.sessions.UnitOfWork;

import org.springframework.jdbc.datasource.ConnectionHandle;
import org.springframework.jdbc.datasource.SimpleConnectionHandle;
import org.springframework.orm.jpa.DefaultJpaDialect;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionException;

/**
 * {@link org.springframework.orm.jpa.JpaDialect} implementation for
 * Oracle TopLink Essentials. Developed and tested against TopLink Essentials v2.
 *
 * <p>By default, this class acquires a TopLink transaction to get the JDBC Connection
 * early. This allows mixing JDBC and JPA/TopLink operations in the same transaction.
 * In some cases, this eager acquisition of a transaction/connection may impact
 * scalability. In that case, set the "lazyDatabaseTransaction" flag to true if you
 * do not require mixing JDBC and JPA operations in the same transaction. Otherwise,
 * use a {@link org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy}
 * to ensure that the cost of connection acquisition is near zero until code actually
 * needs a JDBC Connection.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 2.0
 * @see #setLazyDatabaseTransaction
 * @see org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy
 */
public class TopLinkJpaDialect extends DefaultJpaDialect {
	
	private boolean lazyDatabaseTransaction = false;


	/**
	 * Set whether to lazily start a database transaction within a TopLink
	 * transaction.
	 * <p>By default, database transactions are started early. This allows
	 * for reusing the same JDBC Connection throughout an entire transaction,
	 * including read operations, and also for exposing TopLink transactions
	 * to JDBC access code (working on the same DataSource).
	 * <p>It is only recommended to switch this flag to "true" when no JDBC access
	 * code is involved in any of the transactions, and when it is acceptable to
	 * perform read operations outside of the transactional JDBC Connection.
	 * @see oracle.toplink.sessions.UnitOfWork#beginEarlyTransaction()
	 */
	public void setLazyDatabaseTransaction(boolean lazyDatabaseTransaction) {
		this.lazyDatabaseTransaction = lazyDatabaseTransaction;
	}


	@Override
	public Object beginTransaction(EntityManager entityManager, TransactionDefinition definition)
			throws PersistenceException, SQLException, TransactionException {

		super.beginTransaction(entityManager, definition);
		if (!definition.isReadOnly() && !this.lazyDatabaseTransaction) {
			// This is the magic bit. As with the existing Spring TopLink integration,
			// begin an early transaction to force TopLink to get a JDBC Connection
			// so that Spring can manage transactions with JDBC as well as TopLink.
			UnitOfWork uow = (UnitOfWork) getSession(entityManager);
			uow.beginEarlyTransaction();
		}
		// Could return the UOW, if there were any advantage in having it later.
		return null;
	}

	@Override
	public ConnectionHandle getJdbcConnection(EntityManager em, boolean readOnly)
			throws PersistenceException, SQLException {

		AbstractSession session = (AbstractSession) getSession(em);
		// The connection was already acquired eagerly in beginTransaction,
		// unless lazyDatabaseTransaction was set to true.
		Connection con = session.getAccessor().getConnection();
		return (con != null ? new SimpleConnectionHandle(con) : null);
	}

	/**
	 * Get a traditional TopLink Session from the given EntityManager.
	 */
	protected Session getSession(EntityManager em) {
		oracle.toplink.essentials.ejb.cmp3.EntityManager emi = (oracle.toplink.essentials.ejb.cmp3.EntityManager) em;
		return emi.getActiveSession();
	}

}

Other Spring Framework examples (source code examples)

Here is a short list of links related to this Spring Framework TopLinkJpaDialect.java source code file:

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