/**
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.camel.component.jpa;
import java.lang.reflect.Method;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.LockModeType;
import javax.persistence.PersistenceException;
import javax.persistence.Query;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.impl.ScheduledPollConsumer;
import org.apache.camel.util.ObjectHelper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.orm.jpa.JpaCallback;
/**
* @version $Revision: 541335 $
*/
public class JpaConsumer extends ScheduledPollConsumer<Exchange> {
private static final transient Log log = LogFactory.getLog(JpaConsumer.class);
private final JpaEndpoint endpoint;
private final TransactionStrategy template;
private QueryFactory queryFactory;
private DeleteHandler<Object> deleteHandler;
private String query;
private String namedQuery;
private String nativeQuery;
public JpaConsumer(JpaEndpoint endpoint, Processor processor) {
super(endpoint, processor);
this.endpoint = endpoint;
this.template = endpoint.createTransactionStrategy();
}
protected void poll() throws Exception {
template.execute(new JpaCallback() {
public Object doInJpa(EntityManager entityManager) throws PersistenceException {
Query query = getQueryFactory().createQuery(entityManager);
configureParameters(query);
List results = query.getResultList();
for (Object result : results) {
if (log.isDebugEnabled()) {
log.debug("Processing new entity: " + result);
}
if (lockEntity(result, entityManager)) {
// lets turn the result into an exchange and fire it into the processor
Exchange exchange = createExchange(result);
try {
getProcessor().process(exchange);
} catch (Exception e) {
throw new PersistenceException(e);
}
getDeleteHandler().deleteObject(entityManager, result);
}
}
entityManager.flush();
return null;
}
});
}
// Properties
//-------------------------------------------------------------------------
public JpaEndpoint getEndpoint() {
return endpoint;
}
public QueryFactory getQueryFactory() {
if (queryFactory == null) {
queryFactory = createQueryFactory();
if (queryFactory == null) {
throw new IllegalArgumentException("No queryType property configured on this consumer, nor an entityType configured on the endpoint so cannot consume");
}
}
return queryFactory;
}
public void setQueryFactory(QueryFactory queryFactory) {
this.queryFactory = queryFactory;
}
public DeleteHandler getDeleteHandler() {
if (deleteHandler == null) {
deleteHandler = createDeleteHandler();
}
return deleteHandler;
}
public void setDeleteHandler(DeleteHandler deleteHandler) {
this.deleteHandler = deleteHandler;
}
public String getNamedQuery() {
return namedQuery;
}
public void setNamedQuery(String namedQuery) {
this.namedQuery = namedQuery;
}
public String getNativeQuery() {
return nativeQuery;
}
public void setNativeQuery(String nativeQuery) {
this.nativeQuery = nativeQuery;
}
public String getQuery() {
return query;
}
public void setQuery(String query) {
this.query = query;
}
// Implementation methods
//-------------------------------------------------------------------------
/**
* A strategy method to lock an object with an exclusive lock so that it can be processed
*
* @param entity the entity to be locked
* @param entityManager
* @return true if the entity was locked
*/
protected boolean lockEntity(Object entity, EntityManager entityManager) {
try {
if (log.isDebugEnabled()) {
log.debug("Acquiring exclusive lock on entity: " + entity);
}
entityManager.lock(entity, LockModeType.WRITE);
return true;
}
catch (Exception e) {
if (log.isDebugEnabled()) {
log.debug("Failed to achieve lock on entity: " + entity + ". Reason: " + e, e);
}
return false;
}
}
protected QueryFactory createQueryFactory() {
if (query != null) {
return QueryBuilder.query(query);
}
else if (namedQuery != null) {
return QueryBuilder.namedQuery(namedQuery);
}
else if (nativeQuery != null) {
return QueryBuilder.nativeQuery(nativeQuery);
}
else {
Class<?> entityType = endpoint.getEntityType();
if (entityType == null) {
return null;
}
else {
return QueryBuilder.query("select x from " + entityType.getName() + " x");
}
}
}
protected DeleteHandler<Object> createDeleteHandler() {
// TODO auto-discover an annotation in the entity bean to indicate the process completed method call?
Class<?> entityType = getEndpoint().getEntityType();
if (entityType != null) {
List<Method> methods = ObjectHelper.findMethodsWithAnnotation(entityType, Consumed.class);
if (methods.size() > 1) {
throw new IllegalArgumentException("Only one method can be annotated with the @Consumed annotation but found: " + methods);
}
else if (methods.size() == 1) {
final Method method = methods.get(0);
return new DeleteHandler<Object>() {
public void deleteObject(EntityManager entityManager, Object entityBean) {
ObjectHelper.invokeMethod(method, entityBean);
}
};
}
}
return new DeleteHandler<Object>() {
public void deleteObject(EntityManager entityManager, Object entityBean) {
entityManager.remove(entityBean);
}
};
}
protected void configureParameters(Query query) {
int maxResults = endpoint.getMaximumResults();
if (maxResults > 0) {
query.setMaxResults(maxResults);
}
}
protected Exchange createExchange(Object result) {
Exchange exchange = endpoint.createExchange();
exchange.getIn().setBody(result);
return exchange;
}
}