Updated FlatFileItemWriter to eliminate empty line at EOF

Author: parikshitdutta

spring-batch-core/src/test/resources/expectedOutput.ldif

@@ -71,5 +71,4 @@ objectclass: person
 objectclass: organizationalPerson
 sn: Jensen
 cn: Horatio Jensen
-cn: Horatio N Jensen
-
+cn: Horatio N Jensen

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2018 the original author or authors.
+ * Copyright 2006-2021 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.batch.item.file;
 
+import java.util.Iterator;
 import java.util.List;
 
 import org.springframework.batch.item.file.transform.LineAggregator;
@@ -39,6 +40,7 @@
  * @author Dave Syer
  * @author Michael Minella
  * @author Mahmoud Ben Hassine
+ * @author Parikshit Dutta
  */
 public class FlatFileItemWriter<T> extends AbstractFileItemWriter<T> {
 
@@ -74,8 +76,16 @@ public void setLineAggregator(LineAggregator<T> lineAggregator) {
 	@Override
 	public String doWrite(List<? extends T> items) {
 		StringBuilder lines = new StringBuilder();
-		for (T item : items) {
-			lines.append(this.lineAggregator.aggregate(item)).append(this.lineSeparator);
+		Iterator<? extends T> iterator = items.iterator();
+		if (hasExistingItems() && iterator.hasNext()) {
+			lines.append(lineSeparator);
+		}
+		while (iterator.hasNext()) {
+			T item = iterator.next();
+			lines.append(this.lineAggregator.aggregate(item));
+			if (iterator.hasNext()) {
+				lines.append(lineSeparator);
+			}
 		}
 		return lines.toString();
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2018 the original author or authors.
+ * Copyright 2006-2021 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.
@@ -59,6 +59,7 @@
  * @author Dave Syer
  * @author Michael Minella
  * @author Mahmoud Ben Hassine
+ * @author Parikshit Dutta
  *
  * @since 4.1
  */
@@ -271,6 +272,7 @@ public void close() {
 		if (state != null) {
 			try {
 				if (footerCallback != null && state.outputBufferedWriter != null) {
+					state.outputBufferedWriter.write(lineSeparator);
 					footerCallback.writeFooter(state.outputBufferedWriter);
 					state.outputBufferedWriter.flush();
 				}
@@ -325,7 +327,6 @@ private void doOpen(ExecutionContext executionContext) throws ItemStreamExceptio
 			if (headerCallback != null) {
 				try {
 					headerCallback.writeHeader(outputState.outputBufferedWriter);
-					outputState.write(lineSeparator);
 				}
 				catch (IOException e) {
 					throw new ItemStreamException("Could not write headers.  The file may be corrupt.", e);
@@ -359,6 +360,15 @@ public void update(ExecutionContext executionContext) {
 		}
 	}
 
+	protected boolean hasExistingItems() {
+		try {
+			return (state.position() > 0);
+		}
+		catch (IOException ioException) {
+			throw new ItemStreamException("ItemStream is not able to read offset position");
+		}
+	}
+
 	// Returns object representing state.
 	protected OutputState getOutputState() {
 		if (state == null) {

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/FlatFileItemWriterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2007 the original author or authors.
+ * Copyright 2006-2021 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.
@@ -296,7 +296,7 @@ public void testWriteRecordWithrecordSeparator() throws Exception {
 		writer.open(executionContext);
 		writer.write(Arrays.asList(new String[] { "1", "2" }));
 		String lineFromFile = readLine();
-		assertEquals("1|2|", lineFromFile);
+		assertEquals("1|2", lineFromFile);
 	}
 
 	@Test