RESOLVED - BATCH-828: org.springframework.batch.item.file.MultiResourceItemReader should allow for no resources

graceful handling for non-existing input resources

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

@@ -92,6 +92,8 @@ public class FlatFileItemReader<T> extends AbstractItemReaderItemStream<T> imple
 
 	private LineCallbackHandler headerCallback;
 
+	private boolean noInput;
+
 	public FlatFileItemReader() {
 		setName(ClassUtils.getShortName(FlatFileItemReader.class));
 	}
@@ -213,8 +215,13 @@ public class FlatFileItemReader<T> extends AbstractItemReaderItemStream<T> imple
 	 */
 	protected void doOpen() throws Exception {
 		Assert.notNull(resource, "Input resource must not be null");
-		Assert.state(resource.exists(), "Resource must exist: [" + resource + "]");
 
+		noInput = false;
+		if (!resource.exists()) {
+			noInput = true;
+			log.warn("Input resource does not exist");
+			return;
+		}
 		try {
 			reader = new BufferedReader(new InputStreamReader(resource.getInputStream(), encoding));
 		}
@@ -249,6 +256,9 @@ public class FlatFileItemReader<T> extends AbstractItemReaderItemStream<T> imple
 	 * {@link #setFieldSetMapper(FieldSetMapper)}.
 	 */
 	protected T doRead() throws Exception {
+		if (noInput) {
+			return null;
+		}
 		String record = readRecord();
 
 		if (record != null) {

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

@@ -45,7 +45,7 @@ public class MultiResourceItemReader<T> implements ItemReader<T>, ItemStream {
 	private boolean saveState = true;
 	
 	// signals there are no resources to read -> just return null on first read
-	private boolean emptyInput;
+	private boolean noInput;
 
 	private Comparator<Resource> comparator = new Comparator<Resource>() {
 
@@ -67,7 +67,7 @@ public class MultiResourceItemReader<T> implements ItemReader<T>, ItemStream {
 	 */
 	public T read() throws Exception, UnexpectedInputException, NoWorkFoundException, ParseException {
 
-		if (emptyInput) {
+		if (noInput) {
 			return null;
 		}
 		
@@ -112,7 +112,7 @@ public class MultiResourceItemReader<T> implements ItemReader<T>, ItemStream {
 	public void close(ExecutionContext executionContext) throws ItemStreamException {
 		index = new MultiResourceIndex();
 		delegate.close(new ExecutionContext());
-		emptyInput = false;
+		noInput = false;
 	}
 
 	/**
@@ -123,10 +123,10 @@ public class MultiResourceItemReader<T> implements ItemReader<T>, ItemStream {
 
 		Assert.notNull(resources, "Resources must be set");
 		
-		emptyInput = false;
+		noInput = false;
 		if (resources.length == 0) {
-			logger.info("No resources to read");
-			emptyInput = true;
+			logger.warn("No resources to read");
+			noInput = true;
 			return;
 		}
 

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

@@ -8,6 +8,8 @@ import javax.xml.stream.XMLInputFactory;
 import javax.xml.stream.XMLStreamException;
 import javax.xml.stream.events.StartElement;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.batch.item.file.ResourceAwareItemReaderItemStream;
 import org.springframework.batch.item.support.AbstractItemReaderItemStream;
 import org.springframework.batch.item.xml.stax.DefaultFragmentEventReader;
@@ -35,6 +37,8 @@ import org.springframework.xml.transform.StaxSource;
 public class StaxEventItemReader<T> extends AbstractItemReaderItemStream<T> implements
 		ResourceAwareItemReaderItemStream<T>, InitializingBean {
 
+	private static final Log logger = LogFactory.getLog(StaxEventItemReader.class);
+	
 	private FragmentEventReader fragmentReader;
 
 	private XMLEventReader eventReader;
@@ -47,6 +51,8 @@ public class StaxEventItemReader<T> extends AbstractItemReaderItemStream<T> impl
 
 	private String fragmentRootElementName;
 
+	private boolean noInput;
+
 	public StaxEventItemReader() {
 		setName(ClassUtils.getShortName(StaxEventItemReader.class));
 	}
@@ -137,7 +143,13 @@ public class StaxEventItemReader<T> extends AbstractItemReaderItemStream<T> impl
 
 	protected void doOpen() throws Exception {
 		Assert.notNull(resource, "The Resource must not be null.");
-		Assert.state(resource.exists(), "Input resource does not exist: [" + resource + "]");
+		
+		noInput = false;
+		if (!resource.exists()) {
+			noInput = true;
+			logger.warn("Input resource does not exist");
+			return;
+		}
 
 		inputStream = resource.getInputStream();
 		eventReader = XMLInputFactory.newInstance().createXMLEventReader(inputStream);
@@ -149,6 +161,11 @@ public class StaxEventItemReader<T> extends AbstractItemReaderItemStream<T> impl
 	 * Move to next fragment and map it to item.
 	 */
 	protected T doRead() throws Exception {
+		
+		if (noInput) {
+			return null;
+		}
+		
 		T item = null;
 
 		if (moveCursorToNextFragment(fragmentReader)) {