com.mchange.io.impl.LazyReadOnlyMemoryFileImpl Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java v.0.2.3
*
* Copyright (C) 2012 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* 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. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
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();
}
}