RESOLVED - issue BATCH-788: Remove flush/clear from ItemWriter

Done

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

@@ -27,11 +27,10 @@ import java.util.List;
  * </p>
  * 
  * <p>
- * Due to the nature of batch processing, it is expected that most writers will
- * buffer output. A flush method is provided to the interface in order to ensure
- * that any buffers can be flushed before a transaction is committed. Along the
- * same lines, if a transaction has been rolled back, then the contents of any
- * buffers should be thrown away.
+ * The write method is responsible for making sure that any internal buffers are
+ * flushed. If a transaction is active it will also usually be necessary to
+ * discard the output on a subsequent rollback. The resource to which the writer
+ * is sending data should normally be able to handle this itself.
  * </p>
  * 
  * @author Dave Syer
@@ -40,33 +39,12 @@ import java.util.List;
 public interface ItemWriter<T> {
 
 	/**
-	 * Process the supplied data element. Will be called multiple times during a
-	 * larger batch operation. Will not be called with null data in normal
-	 * operation.
+	 * Process the supplied data element. Will not be called with any null items
+	 * in normal operation.
 	 * 
-	 * @throws Exception if there are errors. If the writer is used inside a
-	 * retry or a batch the framework will catch the exception and convert or
-	 * rethrow it as appropriate.
+	 * @throws Exception if there are errors. The framework will catch the
+	 * exception and convert or rethrow it as appropriate.
 	 */
 	void write(List<? extends T> items) throws Exception;
 
-	/**
-	 * Flush any buffers that are being held. This will usually be performed
-	 * prior to committing any transactions.
-	 * @throws FlushFailedException in case of an error.  If this exception is
-	 * thrown the writer may be in an inconsistent state and manual intervention
-	 * might be required to reconcile the data with persistent output.
-	 * @deprecated
-	 */
-	void flush() throws FlushFailedException;
-
-	/**
-	 * Clear any buffers that are being held. This will usually be performed
-	 * prior to rolling back any transactions.
-	 * @throws ClearFailedException in case of an error. If this exception is
-	 * thrown the writer may be in an inconsistent state and manual intervention
-	 * might be required to reconcile the data with persistent output.
-	 * @deprecated
-	 */
-	void clear() throws ClearFailedException;
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/adapter/ItemWriterAdapter.java

@@ -18,8 +18,6 @@ package org.springframework.batch.item.adapter;
 
 import java.util.List;
 
-import org.springframework.batch.item.ClearFailedException;
-import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemWriter;
 
 
@@ -38,20 +36,6 @@ public class ItemWriterAdapter<T> extends AbstractMethodInvokingDelegator<T> imp
     		invokeDelegateMethodWithArgument(item);			
 		}
     }
-
-    /*
-     * No-op, can't call more than one method.
-     * 
-     */
-	public void clear() throws ClearFailedException {
-	}
-
-    /*
-     * No-op, can't call more than one method.
-     * 
-     */
-	public void flush() throws FlushFailedException {
-	}
 	
 }
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/adapter/PropertyExtractingDelegatingItemWriter.java

@@ -18,8 +18,6 @@ package org.springframework.batch.item.adapter;
 
 import java.util.List;
 
-import org.springframework.batch.item.ClearFailedException;
-import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemWriter;
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
@@ -73,9 +71,4 @@ public class PropertyExtractingDelegatingItemWriter<T> extends AbstractMethodInv
 		this.fieldsUsedAsTargetMethodArguments = fieldsUsedAsMethodArguments;
 	}
 
-	public void clear() throws ClearFailedException {
-	}
-
-	public void flush() throws FlushFailedException {
-	}
 }

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

@@ -20,7 +20,6 @@ import java.sql.SQLException;
 import java.util.List;
 
 import org.springframework.batch.item.ItemWriter;
-import org.springframework.batch.item.support.AbstractItemWriter;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.EmptyResultDataAccessException;
@@ -52,7 +51,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * 
  */
-public class BatchSqlUpdateItemWriter<T> extends AbstractItemWriter<T> implements InitializingBean {
+public class BatchSqlUpdateItemWriter<T> implements ItemWriter<T>, InitializingBean {
 
 	private JdbcOperations jdbcTemplate;
 

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

@@ -19,7 +19,6 @@ import java.util.List;
 
 import org.hibernate.SessionFactory;
 import org.springframework.batch.item.ItemWriter;
-import org.springframework.batch.item.support.AbstractItemWriter;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.orm.hibernate3.HibernateOperations;
 import org.springframework.orm.hibernate3.HibernateTemplate;
@@ -29,11 +28,7 @@ import org.springframework.util.Assert;
  * {@link ItemWriter} that is aware of the Hibernate session and can take some
  * responsibilities to do with chunk boundaries away from a less smart
  * {@link ItemWriter} (the delegate). A delegate is required, and will be used
- * to do the actual writing of the item.<br/>
- * 
- * It is expected that {@link #write(List)} is called inside a transaction, and
- * that {@link #flush()} is then subsequently called before the transaction
- * commits, or {@link #clear()} before it rolls back.<br/>
+ * to do the actual writing of the item.<br/><br/>
  * 
  * The writer is thread safe after its properties are set (normal singleton
  * behaviour), so it can be used to write in multiple concurrent transactions.
@@ -45,7 +40,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * 
  */
-public class HibernateAwareItemWriter<T> extends AbstractItemWriter<T> implements InitializingBean {
+public class HibernateAwareItemWriter<T> implements ItemWriter<T>, InitializingBean {
 
 	private ItemWriter<? super T> delegate;
 

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

@@ -6,7 +6,6 @@ import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
 
 import org.springframework.batch.item.ItemWriter;
-import org.springframework.batch.item.support.AbstractItemWriter;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.dao.DataAccessResourceFailureException;
 import org.springframework.orm.jpa.EntityManagerFactoryUtils;
@@ -36,7 +35,7 @@ import org.springframework.util.Assert;
  * @author Thomas Risberg
  * 
  */
-public class JpaAwareItemWriter<T> extends AbstractItemWriter<T> implements InitializingBean {
+public class JpaAwareItemWriter<T> implements ItemWriter<T>, InitializingBean {
 
 	private ItemWriter<? super T> delegate;
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/FlatFileItemWriter.java

@@ -27,7 +27,6 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.springframework.batch.item.ClearFailedException;
 import org.springframework.batch.item.ExecutionContext;
 import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemStream;
@@ -53,11 +52,6 @@ import org.springframework.util.ClassUtils;
  * 
  * Uses buffered writer to improve performance.<br/>
  * 
- * <p>
- * Output lines are buffered until {@link #flush()} is called and only then the
- * actual writing to file occurs.
- * </p>
- * 
  * The implementation is *not* thread-safe.
  * 
  * @author Waseem Malik
@@ -275,9 +269,6 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 		}
 	}
 
-	public void flush() throws FlushFailedException {
-	}
-
 	// Returns object representing state.
 	private OutputState getOutputState() {
 		if (state == null) {
@@ -501,7 +492,4 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 
 	}
 
-	public void clear() throws ClearFailedException {
-	}
-
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/AbstractItemWriter.java

@@ -1,34 +0,0 @@
-/*
- * 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.support;
-
-import org.springframework.batch.item.ClearFailedException;
-import org.springframework.batch.item.FlushFailedException;
-import org.springframework.batch.item.ItemWriter;
-
-/**
- * Abstract {@link ItemWriter}.
- * 
- * @author Lucas Ward
- */
-public abstract class AbstractItemWriter<T> implements ItemWriter<T> {
-
-	public void flush() throws FlushFailedException {
-	}
-
-	public void clear() throws ClearFailedException {
-	}
-}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/CompositeItemWriter.java

@@ -13,7 +13,7 @@ import org.springframework.batch.item.ItemWriter;
  * @author Robert Kasanicky
  * @author Dave Syer
  */
-public class CompositeItemWriter<T> extends AbstractItemWriter<T> {
+public class CompositeItemWriter<T> implements ItemWriter<T> {
 
 	private List<ItemWriter<? super T>> delegates;
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/xml/StaxEventItemWriter.java

@@ -19,7 +19,6 @@ import javax.xml.stream.XMLStreamException;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.springframework.batch.item.ClearFailedException;
 import org.springframework.batch.item.ExecutionContext;
 import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemStream;
@@ -42,9 +41,6 @@ import org.springframework.util.CollectionUtils;
  * This item writer also provides restart, statistics and transaction features
  * by implementing corresponding interfaces.
  * 
- * Output is buffered until {@link #flush()} is called - only then the actual
- * writing to file takes place.
- * 
  * The implementation is *not* thread-safe.
  * 
  * @author Peter Zozom
@@ -463,16 +459,4 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 
 	}
 
-	/**
-	 * Writes buffered items to XML stream and marks restore point.
-	 */
-	public void flush() throws FlushFailedException {
-	}
-
-	/**
-	 * Clear the output buffer
-	 */
-	public void clear() throws ClearFailedException {
-	}
-
 }