org.springframework.batch.item.file.SimpleBinaryBufferedReaderFactory Maven / Gradle / Ivy
/*
* 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
*
* https://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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import org.springframework.core.io.Resource;
/**
* A {@link BufferedReaderFactory} useful for reading simple binary (or text)
* files with no line endings, such as those produced by mainframe copy books.
* The reader splits a stream up across fixed line endings (rather than the
* usual convention based on plain text). The line endings are discarded, just
* as with the default plain text implementation.
*
* @author Dave Syer
*
* @since 2.1
*/
public class SimpleBinaryBufferedReaderFactory implements BufferedReaderFactory {
/**
* The default line ending value.
*/
private static final String DEFAULT_LINE_ENDING = "\n";
private String lineEnding = DEFAULT_LINE_ENDING;
/**
* @param lineEnding {@link String} indicating what defines the end of a "line".
*/
public void setLineEnding(String lineEnding) {
this.lineEnding = lineEnding;
}
@Override
public BufferedReader create(Resource resource, String encoding) throws UnsupportedEncodingException, IOException {
return new BinaryBufferedReader(new InputStreamReader(resource.getInputStream(), encoding), lineEnding);
}
/**
* BufferedReader extension that splits lines based on a line ending, rather
* than the usual plain text conventions.
*
* @author Dave Syer
*
*/
private final class BinaryBufferedReader extends BufferedReader {
private final String ending;
/**
* @param in
*/
private BinaryBufferedReader(Reader in, String ending) {
super(in);
this.ending = ending;
}
@Override
public String readLine() throws IOException {
StringBuilder buffer = null;
synchronized (lock) {
int next = read();
if (next == -1) {
return null;
}
buffer = new StringBuilder();
StringBuilder candidateEnding = new StringBuilder();
while (!isEndOfLine(buffer, candidateEnding, next)) {
next = read();
}
buffer.append(candidateEnding);
}
if (buffer != null && buffer.length() > 0) {
return buffer.toString();
}
return null;
}
/**
* Check for end of line and accumulate a buffer for next time.
*
* @param buffer the current line excluding the candidate ending
* @param candidate a buffer containing accumulated state
* @param next the next character (or -1 for end of file)
* @return true if the values together signify the end of a file
*/
private boolean isEndOfLine(StringBuilder buffer, StringBuilder candidate, int next) {
if (next == -1) {
return true;
}
char c = (char) next;
if (ending.charAt(0) == c || candidate.length() > 0) {
candidate.append(c);
}
if (candidate.length() == 0) {
buffer.append(c);
return false;
}
boolean end = ending.equals(candidate.toString());
if (end) {
candidate.delete(0, candidate.length());
}
else if (candidate.length() >= ending.length()) {
buffer.append(candidate);
candidate.delete(0, candidate.length());
}
return end;
}
}
}