2008-08-08 02:37:18 +02:00
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/*
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2009-08-28 09:15:49 +02:00
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* Copyright 2009 Red Hat, Inc.
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2008-08-08 02:37:18 +02:00
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*
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2009-08-28 09:15:49 +02:00
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* Red Hat licenses this file to you under the Apache License, version 2.0
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* (the "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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2008-08-08 02:37:18 +02:00
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*
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2009-08-28 09:15:49 +02:00
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* http://www.apache.org/licenses/LICENSE-2.0
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2008-08-08 03:27:24 +02:00
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*
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2009-08-28 09:15:49 +02:00
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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2008-08-08 02:37:18 +02:00
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*/
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2008-08-08 03:40:10 +02:00
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package org.jboss.netty.example.factorial;
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2008-08-08 02:37:18 +02:00
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import java.math.BigInteger;
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2008-08-08 03:40:10 +02:00
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import org.jboss.netty.buffer.ChannelBuffer;
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import org.jboss.netty.channel.Channel;
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import org.jboss.netty.channel.ChannelHandlerContext;
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2010-02-02 04:13:15 +01:00
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import org.jboss.netty.handler.codec.frame.CorruptedFrameException;
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2008-08-08 03:40:10 +02:00
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import org.jboss.netty.handler.codec.frame.FrameDecoder;
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2008-08-08 02:37:18 +02:00
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/**
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2010-02-02 04:13:15 +01:00
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* Decodes the binary representation of a {@link BigInteger} prepended
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* with a magic number ('F' or 0x46) and a 32-bit integer length prefix into a
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* {@link BigInteger} instance. For example, { 'F', 0, 0, 0, 1, 42 } will be
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* decoded into new BigInteger("42").
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2008-08-12 13:58:15 +02:00
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*
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2010-01-26 10:04:19 +01:00
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* @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
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* @author <a href="http://gleamynode.net/">Trustin Lee</a>
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2008-08-08 02:37:18 +02:00
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*/
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public class BigIntegerDecoder extends FrameDecoder {
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@Override
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protected Object decode(
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ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
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2008-08-12 13:58:15 +02:00
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// Wait until the length prefix is available.
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2010-02-02 04:13:15 +01:00
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if (buffer.readableBytes() < 5) {
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2008-08-08 02:37:18 +02:00
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return null;
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}
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2009-07-23 11:05:53 +02:00
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2010-02-02 04:13:15 +01:00
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buffer.markReaderIndex();
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// Check the magic number.
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int magicNumber = buffer.readUnsignedByte();
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if (magicNumber != 'F') {
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buffer.resetReaderIndex();
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throw new CorruptedFrameException(
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"Invalid magic number: " + magicNumber);
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}
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2008-08-08 02:37:18 +02:00
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2008-08-12 13:58:15 +02:00
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// Wait until the whole data is available.
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2010-02-02 04:13:15 +01:00
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int dataLength = buffer.readInt();
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if (buffer.readableBytes() < dataLength) {
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buffer.resetReaderIndex();
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2008-08-08 02:37:18 +02:00
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return null;
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}
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2008-08-12 13:58:15 +02:00
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// Convert the received data into a new BigInteger.
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2008-08-08 02:37:18 +02:00
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byte[] decoded = new byte[dataLength];
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buffer.readBytes(decoded);
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return new BigInteger(decoded);
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}
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}
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