com.mchange.io.impl.LazyReadOnlyMemoryFileImpl Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java 0.2.11
*
* Copyright (C) 2015 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of EITHER:
*
* 1) The GNU Lesser General Public License (LGPL), version 2.1, as
* published by the Free Software Foundation
*
* OR
*
* 2) The Eclipse Public License (EPL), version 1.0
*
* You may choose which license to accept if you wish to redistribute
* or modify this work. You may offer derivatives of this work
* under the license you have chosen, or you may provide the same
* choice of license which you have been offered here.
*
* This software 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.
*
* You should have received copies of both LGPL v2.1 and EPL v1.0
* along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
* If not, the text of these licenses are currently available at
*
* LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php
*
*/
package com.mchange.io.impl;
import java.io.*;
import com.mchange.io.*;
public class LazyReadOnlyMemoryFileImpl implements ReadOnlyMemoryFile
{
File file;
byte[] bytes = null;
long last_mod = -1;
int last_len = -1;
public LazyReadOnlyMemoryFileImpl(File file)
{this.file = file;}
public LazyReadOnlyMemoryFileImpl(String fname)
{this(new File(fname));}
public File getFile()
{return file;}
public synchronized byte[] getBytes() throws IOException
{
update();
return bytes;
}
/* should be called in sync'ed methods */
void update() throws IOException
{
if (file.lastModified() > last_mod)
{
if (bytes != null)
last_len = bytes.length;
refreshBytes();
}
}
/* should be called in sync'ed methods */
void refreshBytes() throws IOException
{
ByteArrayOutputStream baos = (last_len > 0 ?
new ByteArrayOutputStream(2 * last_len) :
new ByteArrayOutputStream());
InputStream is = new BufferedInputStream(new FileInputStream(file));
for(int b = is.read(); b >= 0; b = is.read()) baos.write((byte) b);
this.bytes = baos.toByteArray();
this.last_mod = file.lastModified();
}
}