com.doctor.netty5.example.factorial_algorithm.BigIntegerDecoder.java Source code

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Here is the source code for com.doctor.netty5.example.factorial_algorithm.BigIntegerDecoder.java

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/*
 * Copyright (C) 2014-present  The  Netty5-2015  Authors
 *
 * https://github.com/sdcuike
 *
 * Licensed 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 com.doctor.netty5.example.factorial_algorithm;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.math.BigInteger;
import java.util.List;

/**
 * @author doctor
 *
 * @time 201577
 * 
 */
public final class BigIntegerDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        // ? ?F +  +  -> 1 + 4 + ??
        // ??/
        if (in.readableBytes() < 5) {
            return; // F + 
        }

        in.markReaderIndex();
        short magicNumber = in.readUnsignedByte();// ?F
        if (magicNumber != 'F') {
            in.resetReaderIndex();
            throw new RuntimeException("magicNumber must be 'F' ");
        }

        // ???
        int dataLength = in.readInt();

        if (in.readableBytes() < dataLength) {
            in.resetReaderIndex();
            return;
        }

        byte[] data = new byte[dataLength];
        in.readBytes(data);
        out.add(new BigInteger(data));
    }

}