Michael Bayne
6e9077780c
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5829 542714f4-19e9-0310-aa3c-eee0fc999fb1
94 lines
3.2 KiB
Java
94 lines
3.2 KiB
Java
//
|
|
// $Id$
|
|
//
|
|
// Narya library - tools for developing networked games
|
|
// Copyright (C) 2002-2009 Three Rings Design, Inc., All Rights Reserved
|
|
// http://www.threerings.net/code/narya/
|
|
//
|
|
// This library is free software; you can redistribute it and/or modify it
|
|
// under the terms of the GNU Lesser General Public License as published
|
|
// by the Free Software Foundation; either version 2.1 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// This library 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 library; if not, write to the Free Software
|
|
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
|
|
package com.threerings.io;
|
|
|
|
import java.nio.ByteBuffer;
|
|
|
|
/**
|
|
* The framing output stream accumulates output into a byte array just
|
|
* like the byte array output stream, but can then be instructed to send
|
|
* its contents over a channel, prefixed by the length (written as an
|
|
* integer) of the entire frame (contents plus length prefix). It does
|
|
* this efficiently so that data is copied as little as possible and so
|
|
* that the output stream to which the data is written need not be
|
|
* buffered because the framed output is written in a single call to
|
|
* <code>write()</code>.
|
|
*
|
|
* <p><em>Note:</em> The framing output stream does not synchronize writes
|
|
* to its internal buffer. It is intended to only be accessed from a
|
|
* single thread.
|
|
*/
|
|
public class FramingOutputStream extends ByteBufferOutputStream
|
|
{
|
|
public FramingOutputStream ()
|
|
{
|
|
_buffer.put(HEADER_PAD);
|
|
}
|
|
|
|
@Override // documentation inherited
|
|
public ByteBuffer flip ()
|
|
{
|
|
throw new UnsupportedOperationException("Use frameAndReturnBuffer() instead.");
|
|
}
|
|
|
|
@Override // documentation inherited
|
|
public void reset ()
|
|
{
|
|
throw new UnsupportedOperationException("Use resetFrame() instead.");
|
|
}
|
|
|
|
/**
|
|
* Writes the frame length to the beginning of our buffer and returns
|
|
* it for writing to the appropriate channel. This should be followed
|
|
* by a call to {@link #resetFrame} when the frame has been written.
|
|
*/
|
|
public ByteBuffer frameAndReturnBuffer ()
|
|
{
|
|
// flip the buffer which will limit it to it's current position
|
|
_buffer.flip();
|
|
|
|
// then write the frame length and rewind back to the start of the
|
|
// buffer so that all the data is available
|
|
int count = _buffer.limit();
|
|
_buffer.put((byte)((count >>> 24) & 0xFF));
|
|
_buffer.put((byte)((count >>> 16) & 0xFF));
|
|
_buffer.put((byte)((count >>> 8) & 0xFF));
|
|
_buffer.put((byte)((count >>> 0) & 0xFF));
|
|
_buffer.rewind();
|
|
|
|
return _buffer;
|
|
}
|
|
|
|
/**
|
|
* Resets our internal buffer and prepares to write a new frame.
|
|
*/
|
|
public void resetFrame ()
|
|
{
|
|
_buffer.clear();
|
|
_buffer.put(HEADER_PAD);
|
|
}
|
|
|
|
/** We pad the beginning of our buffer so that we can write the frame
|
|
* length when the time comes. */
|
|
protected static final byte[] HEADER_PAD = new byte[4];
|
|
}
|