BATCH-2462 Allow JpaItemWriter to support persist rather than merge for improved performance.

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/JpaItemWriter.java

@@ -50,6 +50,7 @@ public class JpaItemWriter<T> implements ItemWriter<T>, InitializingBean {
 	protected static final Log logger = LogFactory.getLog(JpaItemWriter.class);
 
 	private EntityManagerFactory entityManagerFactory;
+	private boolean usePersist = false;
 
 	/**
 	 * Set the EntityManager to be used internally.
@@ -59,6 +60,15 @@ public class JpaItemWriter<T> implements ItemWriter<T>, InitializingBean {
 	public void setEntityManagerFactory(EntityManagerFactory entityManagerFactory) {
 		this.entityManagerFactory = entityManagerFactory;
 	}
+	
+	/**
+	 * Set whether the EntityManager should perform a persist instead of a merge.
+	 * 
+	 * @param usePersist whether to use persist instead of merge.
+	 */
+	public void setUsePersist(boolean usePersist) {
+		this.usePersist = usePersist;
+	}
 
 	/**
 	 * Check mandatory properties - there must be an entityManagerFactory.
@@ -98,16 +108,21 @@ public class JpaItemWriter<T> implements ItemWriter<T>, InitializingBean {
 		}
 
 		if (!items.isEmpty()) {
-			long mergeCount = 0;
+			long addedToContextCount = 0;
 			for (T item : items) {
 				if (!entityManager.contains(item)) {
-					entityManager.merge(item);
-					mergeCount++;
+					if(usePersist) {
+						entityManager.persist(item);
+					}
+					else {
+						entityManager.merge(item);
+					}					
+					addedToContextCount++;
 				}
 			}
 			if (logger.isDebugEnabled()) {
-				logger.debug(mergeCount + " entities merged.");
-				logger.debug((items.size() - mergeCount) + " entities found in persistence context.");
+				logger.debug(addedToContextCount + " entities " + (usePersist ? " persisted." : "merged."));
+				logger.debug((items.size() - addedToContextCount) + " entities found in persistence context.");
 			}
 		}
 

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/database/JpaItemWriterPersistTests.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2006-2008 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.batch.item.database;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.util.Arrays;
+import java.util.List;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.orm.jpa.EntityManagerHolder;
+import org.springframework.transaction.support.TransactionSynchronizationManager;
+
+/**
+ * @author Chris Cranford
+ * 
+ */
+public class JpaItemWriterPersistTests {
+
+	EntityManagerFactory emf;
+
+	JpaItemWriter<Object> writer;
+
+	@Before
+	public void setUp() throws Exception {
+		if (TransactionSynchronizationManager.isSynchronizationActive()) {
+			TransactionSynchronizationManager.clearSynchronization();
+		}
+		writer = new JpaItemWriter<Object>();
+		writer.setUsePersist(true);
+		emf = mock(EntityManagerFactory.class,"emf");
+		writer.setEntityManagerFactory(emf);
+	}
+
+	@Test
+	public void testAfterPropertiesSet() throws Exception {
+		writer = new JpaItemWriter<Object>();
+		try {
+			writer.afterPropertiesSet();
+			fail("Expected IllegalArgumentException");
+		}
+		catch (IllegalArgumentException e) {
+			// expected
+			assertTrue("Wrong message for exception: " + e.getMessage(),
+					e.getMessage().indexOf("EntityManagerFactory") >= 0);
+		}
+	}
+	
+	@Test
+	public void testPersist() throws Exception {
+		EntityManager em = mock(EntityManager.class, "em");
+		TransactionSynchronizationManager.bindResource(emf, new EntityManagerHolder(em));
+		List<String> items = Arrays.asList(new String[] { "persist1", "persist2" });
+		writer.write(items);		
+		TransactionSynchronizationManager.unbindResource(emf);
+	}
+	
+}