| 1 | /* |
| 2 | * Copyright 2006-2008 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item.database; |
| 18 | |
| 19 | import java.util.List; |
| 20 | |
| 21 | import javax.persistence.EntityManager; |
| 22 | import javax.persistence.EntityManagerFactory; |
| 23 | |
| 24 | import org.apache.commons.logging.Log; |
| 25 | import org.apache.commons.logging.LogFactory; |
| 26 | import org.springframework.batch.item.ItemWriter; |
| 27 | import org.springframework.beans.factory.InitializingBean; |
| 28 | import org.springframework.dao.DataAccessResourceFailureException; |
| 29 | import org.springframework.orm.jpa.EntityManagerFactoryUtils; |
| 30 | import org.springframework.util.Assert; |
| 31 | |
| 32 | /** |
| 33 | * {@link org.springframework.batch.item.ItemWriter} that is using a JPA |
| 34 | * EntityManagerFactory to merge any Entities that aren't part of the |
| 35 | * persistence context. |
| 36 | * |
| 37 | * It is required that {@link #write(List)} is called inside a transaction.<br/> |
| 38 | * |
| 39 | * The reader must be configured with an |
| 40 | * {@link javax.persistence.EntityManagerFactory} that is capable of |
| 41 | * participating in Spring managed transactions. |
| 42 | * |
| 43 | * The writer is thread safe after its properties are set (normal singleton |
| 44 | * behaviour), so it can be used to write in multiple concurrent transactions. |
| 45 | * |
| 46 | * @author Thomas Risberg |
| 47 | * |
| 48 | */ |
| 49 | public class JpaItemWriter<T> implements ItemWriter<T>, InitializingBean { |
| 50 | |
| 51 | protected static final Log logger = LogFactory.getLog(JpaItemWriter.class); |
| 52 | |
| 53 | private EntityManagerFactory entityManagerFactory; |
| 54 | |
| 55 | /** |
| 56 | * Set the EntityManager to be used internally. |
| 57 | * |
| 58 | * @param entityManagerFactory the entityManagerFactory to set |
| 59 | */ |
| 60 | public void setEntityManagerFactory(EntityManagerFactory entityManagerFactory) { |
| 61 | this.entityManagerFactory = entityManagerFactory; |
| 62 | } |
| 63 | |
| 64 | /** |
| 65 | * Check mandatory properties - there must be an entityManagerFactory. |
| 66 | */ |
| 67 | public void afterPropertiesSet() throws Exception { |
| 68 | Assert.notNull(entityManagerFactory, "An EntityManagerFactory is required"); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Merge all provided items that aren't already in the persistence context |
| 73 | * and then flush the entity manager. |
| 74 | * |
| 75 | * @see org.springframework.batch.item.ItemWriter#write(java.util.List) |
| 76 | */ |
| 77 | public final void write(List<? extends T> items) { |
| 78 | EntityManager entityManager = EntityManagerFactoryUtils.getTransactionalEntityManager(entityManagerFactory); |
| 79 | if (entityManager == null) { |
| 80 | throw new DataAccessResourceFailureException("Unable to obtain a transactional EntityManager"); |
| 81 | } |
| 82 | doWrite(entityManager, items); |
| 83 | entityManager.flush(); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Do perform the actual write operation. This can be overridden in a |
| 88 | * subclass if necessary. |
| 89 | * |
| 90 | * @param entityManager the EntityManager to use for the operation |
| 91 | * @param items the list of items to use for the write |
| 92 | */ |
| 93 | protected void doWrite(EntityManager entityManager, List<? extends T> items) { |
| 94 | |
| 95 | if (logger.isDebugEnabled()) { |
| 96 | logger.debug("Writing to JPA with " + items.size() + " items."); |
| 97 | } |
| 98 | |
| 99 | if (!items.isEmpty()) { |
| 100 | long mergeCount = 0; |
| 101 | for (T item : items) { |
| 102 | if (!entityManager.contains(item)) { |
| 103 | entityManager.merge(item); |
| 104 | mergeCount++; |
| 105 | } |
| 106 | } |
| 107 | if (logger.isDebugEnabled()) { |
| 108 | logger.debug(mergeCount + " entities merged."); |
| 109 | logger.debug((items.size() - mergeCount) + " entities found in persistence context."); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | } |
| 114 | |
| 115 | } |