/*
* 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</code> method or - preferably -
* via a shared <code>EntityManager</code> 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</code>
* method that converts them to exceptions that are compatible with the
* <code>org.springframework.dao</code> 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</i> 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</code> 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);
}
}
}
}
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