/*
* The Kuali Financial System, a comprehensive financial management system for higher education.
*
* Copyright 2005-2014 The Kuali Foundation
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.kuali.kfs.module.ld.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.log4j.Logger;
import org.kuali.kfs.gl.exception.LoadException;
import org.kuali.kfs.module.ld.businessobject.LaborOriginEntry;
/**
* This class lazy loads the origin entries in a flat file. This implementation uses a limited amount of memory because it does not
* pre-load all of the origin entries at once. (Assuming that the Java garbage collector is working well). However, if the code that
* uses this iterator stores the contents of this iterator in a big list somewhere, then a lot of memory may be consumed, depending
* on the size of the file.
*/
public class LaborOriginEntryFileIterator implements Iterator<LaborOriginEntry> {
private static Logger LOG = Logger.getLogger(LaborOriginEntryFileIterator.class);
protected LaborOriginEntry nextEntry;
protected BufferedReader reader;
protected int lineNumber;
protected boolean autoCloseReader;
/**
* Constructs a LaborOriginEntryFileIterator
*
* @param reader a reader representing flat-file origin entries
* @param autoCloseReader whether to automatically close the reader when the end of origin entries has been reached (i.e. when
* hasNext() returns false)
*/
public LaborOriginEntryFileIterator(BufferedReader reader) {
this(reader, true);
}
/**
* Constructs a LaborOriginEntryFileIterator
*
* @param reader a reader representing flat-file origin entries
* @param autoCloseReader whether to automatically close the reader when the end of origin entries has been reached (i.e. when
* hasNext() returns false)
*/
public LaborOriginEntryFileIterator(BufferedReader reader, boolean autoCloseReader) {
if (reader == null) {
LOG.error("reader is null in the LaborOriginEntryFileIterator!");
throw new IllegalArgumentException("reader is null!");
}
this.reader = reader;
nextEntry = null;
lineNumber = 0;
this.autoCloseReader = autoCloseReader;
}
/**
* Constructs a LaborOriginEntryFileIterator When constructed with this method, the file handle will be automatically closed
* when the end of origin entries has been reached (i.e. when hasNext() returns false)
*
* @param file the file
*/
public LaborOriginEntryFileIterator(File file) {
if (file == null) {
LOG.error("reader is null in the LaborOriginEntryFileIterator!");
throw new IllegalArgumentException("reader is null!");
}
try {
this.reader = new BufferedReader(new FileReader(file));
this.autoCloseReader = true;
nextEntry = null;
lineNumber = 0;
}
catch (FileNotFoundException e) {
LOG.error("File not found for LaborOriginEntryFileIterator! " + file.getAbsolutePath(), e);
throw new RuntimeException("File not found for LaborOriginEntryFileIterator! " + file.getAbsolutePath());
}
}
/**
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext() {
if (nextEntry == null) {
fetchNextEntry();
return nextEntry != null;
}
else {
// we have the next entry loaded
return true;
}
}
/**
* @see java.util.Iterator#next()
*/
public LaborOriginEntry next() {
if (nextEntry != null) {
// an entry may have been fetched by hasNext()
LaborOriginEntry temp = nextEntry;
nextEntry = null;
return temp;
}
else {
// maybe next() is called repeatedly w/o calling hasNext. This is a bad idea, but the
// interface allows it
fetchNextEntry();
if (nextEntry == null) {
throw new NoSuchElementException();
}
// clear out the nextEntry to signal that no record has been loaded
LaborOriginEntry temp = nextEntry;
nextEntry = null;
return temp;
}
}
/**
* @see java.util.Iterator#remove()
*/
public void remove() {
throw new UnsupportedOperationException("Cannot remove entry from collection");
}
protected void fetchNextEntry() {
try {
lineNumber++;
String line = reader.readLine();
if (line == null) {
nextEntry = null;
if (autoCloseReader) {
reader.close();
}
}
else {
nextEntry = new LaborOriginEntry();
try {
nextEntry.setFromTextFileForBatch(line, lineNumber - 1);
}
catch (LoadException e) {
// wipe out the next entry so that the next call to hasNext or next will force a new row to be fetched
nextEntry = null;
// if there's an LoadException, then we'll just let it propagate up the call stack
throw e;
}
}
}
catch (IOException e) {
LOG.error("error in the CorrectionDocumentServiceImpl iterator", e);
nextEntry = null;
throw new RuntimeException("error retrieving origin entries");
}
}
/**
* @see java.lang.Object#finalize()
*/
@Override
protected void finalize() throws Throwable {
super.finalize();
if (autoCloseReader && reader != null) {
reader.close();
}
}
}