CmdHandlerInitializer.java

package com.manning.nettyinaction.chapter8;

import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.LineBasedFrameDecoder;

/**
 * @author <a href="mailto:norman.maurer@googlemail.com">Norman Maurer</a>
 */
public class CmdHandlerInitializer extends ChannelInitializer<Channel> {

    @Override
    protected void initChannel(Channel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new CmdDecoder(65 * 1024));
        pipeline.addLast(new CmdHandler());
    }

    public static final class Cmd {
        private final ByteBuf name;
        private final ByteBuf args;

        public Cmd(ByteBuf name, ByteBuf args) {
            this.name = name;
            this.args = args;
        }

        public ByteBuf name() {
            return name;
        }

        public ByteBuf args() {
            return args;
        }
    }

    public static final class CmdDecoder extends LineBasedFrameDecoder {
        public CmdDecoder(int maxLength) {
            super(maxLength);
        }

        @Override
        protected Object decode(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
            ByteBuf frame =  (ByteBuf) super.decode(ctx, buffer);
            if (frame == null) {
                return null;
            }
            int index = frame.indexOf(frame.readerIndex(), frame.writerIndex(), (byte) ' ');
            return new Cmd(frame.slice(frame.readerIndex(), index), frame.slice(index +1, frame.writerIndex()));
        }
    }

    public static final class CmdHandler extends SimpleChannelInboundHandler<Cmd> {
        @Override
        public void channelRead0(ChannelHandlerContext ctx, Cmd msg) throws Exception {
            // Do something with the command
        }
    }
}