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Spring Framework example source code file (JpaInterceptor.java)

This example Spring Framework source code file (JpaInterceptor.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

creating, entitymanager, entitymanager, entitymanagerholder, entitymanagerholder, jpaaccessor, jpainterceptor, jpainterceptor, methodinterceptor, object, object, runtimeexception, throwable

The Spring Framework JpaInterceptor.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;

import javax.persistence.EntityManager;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.transaction.support.TransactionSynchronizationManager;

/**
 * This interceptor binds a new JPA EntityManager to the thread before a method
 * call, closing and removing it afterwards in case of any method outcome.
 * If there already is a pre-bound EntityManager (e.g. from JpaTransactionManager,
 * or from a surrounding JPA-intercepted method), the interceptor simply participates in it.
 *
 * <p>Application code must retrieve a JPA EntityManager via the
 * <code>EntityManagerFactoryUtils.getEntityManager method or - preferably -
 * via a shared <code>EntityManager reference, to be able to detect a
 * thread-bound EntityManager. Typically, the code will look like as follows:
 *
 * <pre>
 * public void doSomeDataAccessAction() {
 *   this.entityManager...
 * }</pre>
 *
 * <p>Note that this interceptor automatically translates PersistenceExceptions,
 * via delegating to the <code>EntityManagerFactoryUtils.convertJpaAccessException
 * method that converts them to exceptions that are compatible with the
 * <code>org.springframework.dao exception hierarchy (like JpaTemplate does).
 *
 * <p>This class can be considered a declarative alternative to JpaTemplate's
 * callback approach. The advantages are:
 * <ul>
 * <li>no anonymous classes necessary for callback implementations;
 * <li>the possibility to throw any application exceptions from within data access code.
 * </ul>
 *
 * <p>The drawback is the dependency on interceptor configuration. However, note
 * that this interceptor is usually <i>not necessary in scenarios where the
 * data access code always executes within transactions. A transaction will always
 * have a thread-bound EntityManager in the first place, so adding this interceptor
 * to the configuration just adds value when fine-tuning EntityManager settings
 * like the flush mode - or when relying on exception translation.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see JpaTransactionManager
 * @see JpaTemplate
 */
public class JpaInterceptor extends JpaAccessor implements MethodInterceptor {

	private boolean exceptionConversionEnabled = true;


	/**
	 * Set whether to convert any PersistenceException raised to a Spring DataAccessException,
	 * compatible with the <code>org.springframework.dao exception hierarchy.
	 * <p>Default is "true". Turn this flag off to let the caller receive raw exceptions
	 * as-is, without any wrapping.
	 * @see org.springframework.dao.DataAccessException
	 */
	public void setExceptionConversionEnabled(boolean exceptionConversionEnabled) {
		this.exceptionConversionEnabled = exceptionConversionEnabled;
	}


	public Object invoke(MethodInvocation methodInvocation) throws Throwable {
		// Determine current EntityManager: either the transactional one
		// managed by the factory or a temporary one for the given invocation.
		EntityManager em = getTransactionalEntityManager();
		boolean isNewEm = false;
		if (em == null) {
			logger.debug("Creating new EntityManager for JpaInterceptor invocation");
			em = createEntityManager();
			isNewEm = true;
			TransactionSynchronizationManager.bindResource(getEntityManagerFactory(), new EntityManagerHolder(em));
		}

		try {
			Object retVal = methodInvocation.proceed();
			flushIfNecessary(em, !isNewEm);
			return retVal;
		}
		catch (RuntimeException rawException) {
			if (this.exceptionConversionEnabled) {
				// Translation enabled. Translate if we understand the exception.
				throw translateIfNecessary(rawException);
			}
			else {
				// Translation not enabled. Don't try to translate.
				throw rawException;
			}
		}
		finally {
			if (isNewEm) {
				TransactionSynchronizationManager.unbindResource(getEntityManagerFactory());
				EntityManagerFactoryUtils.closeEntityManager(em);
			}
		}
	}

}

Other Spring Framework examples (source code examples)

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

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