The main problem here is that FlatFileItemReader assumes you have line breaks, which you don’t. The clearest solution to me is to copy/paste the class and swap out the readLine() method with one that takes in the appropriate number of characters. Unfortunately, because much of the class is private, you can’t easily extend and override.
package org.springframework.batch.item.file;
import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.Charset;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.batch.item.ReaderNotOpenException;
import org.springframework.batch.item.file.separator.RecordSeparatorPolicy;
import org.springframework.batch.item.file.separator.SimpleRecordSeparatorPolicy;
import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
/**
* Modified version of {@link FlatFileItemWriter} which reads in mainframe style files with fixed width and no line breaks.
* Still a restartable {@link ItemReader} that reads lines from input {@link #setResource(Resource)}. Line is defined by the
* {@link #setRecordSeparatorPolicy(RecordSeparatorPolicy)} and mapped to item using {@link #setLineMapper(LineMapper)}.
* If an exception is thrown during line mapping it is rethrown as {@link FlatFileParseException} adding information
* about the problematic line and its line number.
*
* @author Robert Kasanicky
* @author Dean Clark
*/
public class FixedLengthFlatFileItemReader<T> extends AbstractItemCountingItemStreamItemReader<T> implements ResourceAwareItemReaderItemStream<T>, InitializingBean {
private static final Log logger = LogFactory.getLog(FlatFileItemReader.class);
// default encoding for input files
public static final String DEFAULT_CHARSET = Charset.defaultCharset().name();
private RecordSeparatorPolicy recordSeparatorPolicy = new SimpleRecordSeparatorPolicy();
private Resource resource;
private BufferedReader reader;
private int lineCount = 0;
private String[] comments = new String[] { "#" };
private boolean noInput = false;
private String encoding = DEFAULT_CHARSET;
private LineMapper<T> lineMapper;
private int linesToSkip = 0;
private LineCallbackHandler skippedLinesCallback;
private boolean strict = true;
private BufferedReaderFactory bufferedReaderFactory = new DefaultBufferedReaderFactory();
// CHANGE: Added a variable to store Line Length
private Integer lineLength;
public FixedLengthFlatFileItemReader() {
setName(ClassUtils.getShortName(FlatFileItemReader.class));
}
/**
* In strict mode the reader will throw an exception on
* {@link #open(org.springframework.batch.item.ExecutionContext)} if the input resource does not exist.
* @param strict <code>true</code> by default
*/
public void setStrict(final boolean strict) {
this.strict = strict;
}
/**
* @param skippedLinesCallback will be called for each one of the initial skipped lines before any items are read.
*/
public void setSkippedLinesCallback(final LineCallbackHandler skippedLinesCallback) {
this.skippedLinesCallback = skippedLinesCallback;
}
/**
* Public setter for the number of lines to skip at the start of a file. Can be used if the file contains a header
* without useful (column name) information, and without a comment delimiter at the beginning of the lines.
*
* @param linesToSkip the number of lines to skip
*/
public void setLinesToSkip(final int linesToSkip) {
this.linesToSkip = linesToSkip;
}
/**
* Setter for line mapper. This property is required to be set.
* @param lineMapper maps line to item
*/
public void setLineMapper(final LineMapper<T> lineMapper) {
this.lineMapper = lineMapper;
}
/**
* Setter for the encoding for this input source. Default value is {@link #DEFAULT_CHARSET}.
*
* @param encoding a properties object which possibly contains the encoding for this input file;
*/
public void setEncoding(final String encoding) {
this.encoding = encoding;
}
/**
* Factory for the {@link BufferedReader} that will be used to extract lines from the file. The default is fine for
* plain text files, but this is a useful strategy for binary files where the standard BufferedReaader from java.io
* is limiting.
*
* @param bufferedReaderFactory the bufferedReaderFactory to set
*/
public void setBufferedReaderFactory(final BufferedReaderFactory bufferedReaderFactory) {
this.bufferedReaderFactory = bufferedReaderFactory;
}
/**
* Setter for comment prefixes. Can be used to ignore header lines as well by using e.g. the first couple of column
* names as a prefix.
*
* @param comments an array of comment line prefixes.
*/
public void setComments(final String[] comments) {
this.comments = new String[comments.length];
System.arraycopy(comments, 0, this.comments, 0, comments.length);
}
/**
* Public setter for the input resource.
*/
@Override
public void setResource(final Resource resource) {
this.resource = resource;
}
/**
* Public setter for the recordSeparatorPolicy. Used to determine where the line endings are and do things like
* continue over a line ending if inside a quoted string.
*
* @param recordSeparatorPolicy the recordSeparatorPolicy to set
*/
public void setRecordSeparatorPolicy(final RecordSeparatorPolicy recordSeparatorPolicy) {
this.recordSeparatorPolicy = recordSeparatorPolicy;
}
/**
* @return string corresponding to logical record according to
* {@link #setRecordSeparatorPolicy(RecordSeparatorPolicy)} (might span multiple lines in file).
*/
@Override
protected T doRead() throws Exception {
if (noInput) {
return null;
}
final String line = readLine();
if (line == null) {
return null;
} else {
try {
return lineMapper.mapLine(line, lineCount);
} catch (final Exception ex) {
throw new FlatFileParseException("Parsing error at line: " + lineCount + " in resource=["
+ resource.getDescription() + "], input=[" + line + "]", ex, line, lineCount);
}
}
}
/**
* @return next line (skip comments).getCurrentResource
*/
// CHANGE: Modified readLine() to pull in a set number of characters
private String readLine() {
if (reader == null) {
throw new ReaderNotOpenException("Reader must be open before it can be read.");
}
String line = null;
try {
// CHANGE: READ IN LINE BASED ON LINE LENGTH
final char[] chars = new char[lineLength + 1];
final int charsRead = reader.read(chars, 0, lineLength);
if (charsRead <= 10) {
noInput = true;
return null;
}
line = new String(chars);
// END CHANGE: READ IN LINE BASED ON LINE LENGTH
lineCount++;
while (isComment(line)) {
line = reader.readLine();
if (line == null) {
return null;
}
lineCount++;
}
line = applyRecordSeparatorPolicy(line);
} catch (final IOException e) {
// 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;
}
private boolean isComment(final String line) {
for (final String prefix : comments) {
if (line.startsWith(prefix)) {
return true;
}
}
return false;
}
@Override
protected void doClose() throws Exception {
lineCount = 0;
if (reader != null) {
reader.close();
}
}
@Override
protected void doOpen() throws Exception {
Assert.notNull(resource, "Input resource must be set");
Assert.notNull(recordSeparatorPolicy, "RecordSeparatorPolicy must be set");
noInput = true;
if (!resource.exists()) {
if (strict) {
throw new IllegalStateException("Input resource must exist (reader is in 'strict' mode): " + resource);
}
logger.warn("Input resource does not exist " + resource.getDescription());
return;
}
if (!resource.isReadable()) {
if (strict) {
throw new IllegalStateException("Input resource must be readable (reader is in 'strict' mode): "
+ resource);
}
logger.warn("Input resource is not readable " + resource.getDescription());
return;
}
reader = bufferedReaderFactory.create(resource, encoding);
for (int i = 0; i < linesToSkip; i++) {
final String line = readLine();
if (skippedLinesCallback != null) {
skippedLinesCallback.handleLine(line);
}
}
noInput = false;
}
@Override
public void afterPropertiesSet() throws Exception {
Assert.notNull(lineMapper, "LineMapper is required");
// CHANGE: Added an assertion to verify Line Length was provided
Assert.notNull(lineLength, "Line length is required");
}
@Override
protected void jumpToItem(final int itemIndex) throws Exception {
for (int i = 0; i < itemIndex; i++) {
readLine();
}
}
private String applyRecordSeparatorPolicy(String line) throws IOException {
String record = line;
while ((line != null) && !recordSeparatorPolicy.isEndOfRecord(record)) {
line = this.reader.readLine();
if (line == null) {
if (StringUtils.hasText(record)) {
// A record was partially complete since it hasn't ended but
// the line is null
throw new FlatFileParseException("Unexpected end of file before record complete", record, lineCount);
} else {
// Record has no text but it might still be post processed
// to something (skipping preProcess since that was already
// done)
break;
}
} else {
lineCount++;
}
record = recordSeparatorPolicy.preProcess(record) + line;
}
return recordSeparatorPolicy.postProcess(record);
}
// CHANGE: Added a setter for Line Length
public void setLineLength(final Integer lineLength) {
this.lineLength = lineLength;
}
}