BATCH-1615: modified XML and flat file readers to throw new exception

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

@@ -21,8 +21,7 @@ package org.springframework.batch.item;
  * 
  * Implementations are expected to be stateful and will be called multiple times
  * for each batch, with each call to {@link #read()} returning a different value
- * and finally returning <code>null</code> when all input data is
- * exhausted.<br/>
+ * and finally returning <code>null</code> when all input data is exhausted.<br/>
  * 
  * Implementations need *not* be thread safe and clients of a {@link ItemReader}
  * need to be aware that this is the case.<br/>
@@ -44,8 +43,16 @@ public interface ItemReader<T> {
 	 * twice from successive calls (or otherwise), if the first call was in a
 	 * transaction that rolled back.
 	 * 
-	 * @throws Exception if an underlying resource is unavailable.
+	 * @throws ParseException if there is a problem parsing the current record
+	 * (but the next one may still be valid)
+	 * @throws NonTransientResourceException if there is a fatal exception in
+	 * the underlying resource. After throwing this exception implementations
+	 * should endeavour to return null from subsequent calls to read.
+	 * @throws UnexpectedInputException if there is an uncategorised problem
+	 * with the input data. Assume potentially transient, so subsequent calls to
+	 * read might succeed.
+	 * @throws Exception if an there is a non-specific error.
 	 */
-	T read() throws Exception, UnexpectedInputException, ParseException;
+	T read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException;
 
 }

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

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2006-2007 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;
+
+/**
+ * Exception indicating that an error has been encountered doing I/O from a
+ * reader, and the exception should be considered fatal.
+ * 
+ * @author Dave Syer
+ */
+public class NonTransientResourceException extends ItemReaderException {
+
+	/**
+	 * Create a new {@link NonTransientResourceException} based on a message and
+	 * another exception.
+	 * 
+	 * @param message the message for this exception
+	 * @param cause the other exception
+	 */
+	public NonTransientResourceException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	/**
+	 * Create a new {@link NonTransientResourceException} based on a message.
+	 * 
+	 * @param message the message for this exception
+	 */
+	public NonTransientResourceException(String message) {
+		super(message);
+	}
+
+}

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

@@ -223,7 +223,10 @@ public class FlatFileItemReader<T> extends AbstractItemCountingItemStreamItemRea
 			line = applyRecordSeparatorPolicy(line);
 		}
 		catch (IOException e) {
-			throw new FlatFileParseException("Unable to read from resource: [" + resource + "]", e, line, lineCount);
+			// Prevent IOException from recurring indefinitely
+			// if client keeps catching and re-calling
+			noInput = true;
+			throw new NonTransientFlatFileException("Unable to read from resource: [" + resource + "]", e, line, lineCount);
 		}
 		return line;
 	}

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

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2006-2007 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.file;
+
+import org.springframework.batch.item.NonTransientResourceException;
+
+/**
+ * Exception thrown when errors are encountered with the underlying resource.
+ * 
+ * @author Dave Syer
+ */
+public class NonTransientFlatFileException extends NonTransientResourceException {
+
+	private String input;
+
+	private int lineNumber;
+
+	public NonTransientFlatFileException(String message, String input) {
+		super(message);
+		this.input = input;
+	}
+
+	public NonTransientFlatFileException(String message, String input, int lineNumber) {
+		super(message);
+		this.input = input;
+		this.lineNumber = lineNumber;
+	}
+
+	public NonTransientFlatFileException(String message, Throwable cause, String input, int lineNumber) {
+		super(message, cause);
+		this.input = input;
+		this.lineNumber = lineNumber;
+	}
+
+	public String getInput() {
+		return input;
+	}
+
+	public int getLineNumber() {
+		return lineNumber;
+	}
+}

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

@@ -136,8 +136,12 @@ public class StaxEventItemReader<T> extends AbstractItemCountingItemStreamItemRe
 	 * 
 	 * @return <code>true</code> if next fragment was found, <code>false</code>
 	 * otherwise.
+	 * 
+	 * @throws DataAccessResourceFailureException if the cursor could not be
+	 * moved. This will be treated as fatal and subsequent calls to read will
+	 * return null.
 	 */
-	protected boolean moveCursorToNextFragment(XMLEventReader reader) {
+	protected boolean moveCursorToNextFragment(XMLEventReader reader) throws DataAccessResourceFailureException {
 		try {
 			while (true) {
 				while (reader.peek() != null && !reader.peek().isStartElement()) {
@@ -215,7 +219,16 @@ public class StaxEventItemReader<T> extends AbstractItemCountingItemStreamItemRe
 
 		T item = null;
 
-		if (moveCursorToNextFragment(fragmentReader)) {
+		boolean success = false;
+		try {
+			success = moveCursorToNextFragment(fragmentReader);
+		}
+		catch (DataAccessResourceFailureException e) {
+			// Prevent caller from retrying indefinitely since this is fatal
+			noInput = true;
+			throw e;
+		}
+		if (success) {
 			fragmentReader.markStartFragment();
 
 			@SuppressWarnings("unchecked")