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Added LengthFieldPrepender to prepend a length field easily

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This commit is contained in:
Trustin Lee 2009-01-07 02:14:12 +00:00
parent 8e94c0cd60
commit 5f15d91c41
1 changed files with 82 additions and 0 deletions
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src/main/java/org/jboss/netty/handler/codec/frame/LengthFieldPrepender.java Normal file
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/*
* JBoss, Home of Professional Open Source
*
* Copyright 2009, Red Hat Middleware LLC, and individual contributors
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
* full listing of individual contributors.
*
* This 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 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; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.netty.handler.codec.frame;
import static org.jboss.netty.buffer.ChannelBuffers.*;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
/**
* TODO Documentation
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
* @version $Rev$, $Date$
*/
public class LengthFieldPrepender extends OneToOneEncoder {
private final int lengthFieldLength;
public LengthFieldPrepender(int lengthFieldLength) {
if (lengthFieldLength != 1 && lengthFieldLength != 2 &&
lengthFieldLength != 3 && lengthFieldLength != 4 &&
lengthFieldLength != 8) {
throw new IllegalArgumentException(
"lengthFieldLength must be either 1, 2, 3, 4, or 8: " +
lengthFieldLength);
}
this.lengthFieldLength = lengthFieldLength;
}
@Override
protected Object encode(
ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
ChannelBuffer header = channel.getConfig().getBufferFactory().getBuffer(lengthFieldLength);
ChannelBuffer body = (ChannelBuffer) msg;
switch (lengthFieldLength) {
case 1:
header.writeByte((byte) body.readableBytes());
break;
case 2:
header.writeShort((short) body.readableBytes());
break;
case 3:
header.writeMedium(body.readableBytes());
break;
case 4:
header.writeInt(body.readableBytes());
break;
case 8:
header.writeLong(body.readableBytes());
break;
default:
throw new Error("should not reach here");
}
return wrappedBuffer(header, body);
}
}