public static void main(String[] args) {
				//1.线程池配置
        ServerBootstrap bootstrap = new ServerBootstrap();
        NioEventLoopGroup parentGroup = new NioEventLoopGroup(1);
        NioEventLoopGroup childGroup = new NioEventLoopGroup(4);
        bootstrap.group(parentGroup, childGroup);
        //2.服务端Channel配置
        bootstrap.channel(NioServerSocketChannel.class);
        bootstrap.option(ChannelOption.SO_BACKLOG, 1024);
       
        //3.子Channel配置
        bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {

            @Override
            protected void initChannel(SocketChannel channel) throws Exception {
                //解码器
                channel.pipeline().addLast(new LineBasedFrameDecoder(1024));
                channel.pipeline().addLast(new StringDecoder(StandardCharsets.UTF_8));
                //业务handler
                channel.pipeline().addLast(new BusinessHandler());
                //编码器
                channel.pipeline().addLast(new StringEncoder(StandardCharsets.UTF_8));
            }
        });

         try {
            ChannelFuture future = bootstrap.bind(7001).syncUninterruptibly();
            future.channel().closeFuture().sync();
        } catch (Exception e) {
           	//todo
        }finally {
            parentGroup.shutdownGracefully();
            childGroup.shutdownGracefully();
        }
    }


    static class BusinessHandler extends ChannelInboundHandlerAdapter {
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            String s = (String) msg;
            String ret = "";
            if ("today".equals(s)) {
                ret = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
            } else if ("time".equals(s)) {
                ret = new SimpleDateFormat("hh:mm:ss").format(new Date());
            }
            ret += "\r\n";
            ctx.channel().writeAndFlush(ret);
        }
    }

整个应用搭建的过程很简单，归纳起来有四步

1.Reactor线程池配置

2.服务端Channel配置

3.子Channel配置（通过服务端通道创建的子通道）

4.绑定本地端口并启动服务

Reactor线程池配置

我们新建两个Reactor线程池parentGroup和childGroup

parentGroup是服务端通道使用，用于接受新的客户端连接（accept）

childGroup用于处理所有服务端通道创建子通道的网络I/O请求

ServerBootstrap bootstrap = new ServerBootstrap(); 
NioEventLoopGroup parentGroup = new NioEventLoopGroup(1);
NioEventLoopGroup childGroup = new NioEventLoopGroup(4);
bootstrap.group(parentGroup, childGroup);

bootstrap.channel(NioServerSocketChannel.class);

bootstrap.option(ChannelOption.SO_BACKLOG, 1024);
bootstrap.attr(AttributeKey.newInstance("TEST"), new Object());

ChannelFuture future = bootstrap.bind(7001).syncUninterruptibly();

 public ChannelFuture bind(int inetPort) {
        return bind(new InetSocketAddress(inetPort));
 }

 public ChannelFuture bind(SocketAddress localAddress) {
        this.validate();
        return this.doBind(localAddress);
 }
 
 private ChannelFuture doBind(final SocketAddress localAddress) {
   			//1. 初始化NioServerSocketChannel,并且注册到EventLoopGroup
        final ChannelFuture regFuture = initAndRegister();
        final Channel channel = regFuture.channel();
        //2.1. 注册失败，直接返回
        if (regFuture.cause() != null) {
            return regFuture;
        }
        if (regFuture.isDone()) {
            // At this point we know that the registration was complete and successful.
            ChannelPromise promise = channel.newPromise();
          	//2.2. 注册成功，直接bind本地端口
            doBind0(regFuture, channel, localAddress, promise);
            return promise;
        } else {
            // Registration future is almost always fulfilled already, but just in case it's not.
            final PendingRegistrationPromise promise = new PendingRegistrationPromise(channel);
          //3.如果注册还未知（因为是异步操作），添加listener到regFuture对象上用于注册完成后进行回调处理
          regFuture.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    Throwable cause = future.cause();
                    if (cause != null) {
                        promise.setFailure(cause);
                    } else {
                        promise.registered();
                        doBind0(regFuture, channel, localAddress, promise);
                    }
                }
            });
            return promise;
        }
    }

final ChannelFuture initAndRegister() {
        Channel channel = null;
        try {
            //1. 实例化，基于反射的工厂方法
            channel = channelFactory.newChannel();
            init(channel);
        } catch (Throwable t) {
            //
        }
        ChannelFuture regFuture = config().group().register(channel);
        if (regFuture.cause() != null) {
            //
        }
        return regFuture;
    }

void init(Channel channel) {
        setChannelOptions(channel, newOptionsArray(), logger);
        setAttributes(channel, attrs0().entrySet().toArray(EMPTY_ATTRIBUTE_ARRAY));

        ChannelPipeline p = channel.pipeline();

        final EventLoopGroup currentChildGroup = childGroup;
        final ChannelHandler currentChildHandler = childHandler;
        final Entry<ChannelOption<?>, Object>[] currentChildOptions;
        synchronized (childOptions) {
            currentChildOptions = childOptions.entrySet().toArray(EMPTY_OPTION_ARRAY);
        }
        final Entry<AttributeKey<?>, Object>[] currentChildAttrs = childAttrs.entrySet().toArray(EMPTY_ATTRIBUTE_ARRAY);

        p.addLast(new ChannelInitializer<Channel>() {
            @Override
            public void initChannel(final Channel ch) {
                final ChannelPipeline pipeline = ch.pipeline();
                ChannelHandler handler = config.handler();
                if (handler != null) {
                    pipeline.addLast(handler);
                }
                ch.eventLoop().execute(new Runnable() {
                    @Override
                    public void run() {
                        pipeline.addLast(new ServerBootstrapAcceptor(
                                ch, currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs));
                    }
                });
            }
        });
    }