/*
* Copyright 2009 Red Hat, Inc.
*
* Red Hat licenses this file to you under the Apache License, version 2.0
* (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.jboss.netty.example.factorial;
import java.math.BigInteger;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.CorruptedFrameException;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
/**
* Decodes the binary representation of a {@link BigInteger} prepended
* with a magic number ('F' or 0x46) and a 32-bit integer length prefix into a
* {@link BigInteger} instance. For example, { 'F', 0, 0, 0, 1, 42 } will be
* decoded into new BigInteger("42").
*
* @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
* @author <a href="http://gleamynode.net/">Trustin Lee</a>
*
* @version $Rev: 2125 $, $Date: 2010-02-02 12:13:15 +0900 (Tue, 02 Feb 2010) $
*/
public class BigIntegerDecoder extends FrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
// Wait until the length prefix is available.
if (buffer.readableBytes() < 5) {
return null;
}
buffer.markReaderIndex();
// Check the magic number.
int magicNumber = buffer.readUnsignedByte();
if (magicNumber != 'F') {
buffer.resetReaderIndex();
throw new CorruptedFrameException(
"Invalid magic number: " + magicNumber);
}
// Wait until the whole data is available.
int dataLength = buffer.readInt();
if (buffer.readableBytes() < dataLength) {
buffer.resetReaderIndex();
return null;
}
// Convert the received data into a new BigInteger.
byte[] decoded = new byte[dataLength];
buffer.readBytes(decoded);
System.out.println("BigIntegerDecoder: decode ="+new BigInteger(decoded));
return new BigInteger(decoded);
}
}