老师您上班辛苦，不着急，慢慢看哈。我是已经看了好几遍，跟着视频敲，但是还是查不出原因。。。
两个地方跟着视频敲之后被要求强转：
Channel channel = (Channel) channelHandlerContext.channel();
System.out.println(((io.netty.channel.Channel) channel).remoteAddress());
麻烦您了，阿里嘎多！

package imoocNettyHello;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;


public class HelloServer {
 
/**
   * 客户端发起一个请求，然后服务器响应“Hello Netty!”
   * @param args
 * @throws Exception 
   */
	public static void main(String[] args) throws Exception {
		// 1.创建一个主线程组
		EventLoopGroup bossGroup = new NioEventLoopGroup();
		
		//2.创建一个从线程组
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		
		//3.创建一个服务器的启动类
		try {
			ServerBootstrap serverBootstrap = new ServerBootstrap();
			serverBootstrap.group(bossGroup, workerGroup)
			              .channel(NioServerSocketChannel.class)
			              .childHandler(new HelloServerInitializer());
			
			//ServerBootstrap要绑定端口号：
			ChannelFuture channelFuture = serverBootstrap.bind(8080).sync();
			
			//关闭端口号
			channelFuture.channel().closeFuture().sync();
			
		}finally {
			//优雅地关闭主线程 和 从线程
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
			
		}
		
		
		
		

	}

}

package imoocNettyHello;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;


public class HelloServerInitializer extends ChannelInitializer<SocketChannel> {



	@Override
	protected void initChannel(SocketChannel channel) throws Exception {
		// 利用channel 拿到 pipeline
		ChannelPipeline pipeline = channel.pipeline();
		pipeline.addLast("HttpServerCodec",new HttpServerCodec());
		pipeline.addLast("customHandler",new CustomHandler());
		
	}

	

}

package imoocNettyHello;

import java.nio.channels.Channel;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpObject;

import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.CharsetUtil;

public class CustomHandler extends SimpleChannelInboundHandler<HttpObject>{

	@Override
	protected void channelRead0(ChannelHandlerContext channelHandlerContext, HttpObject msg) throws Exception {
		// 利用上下文拿到channel
		Channel channel = (Channel) channelHandlerContext.channel();
		//打出来我们客户端的位置
		System.out.println(((io.netty.channel.Channel) channel).remoteAddress());
		
	
			//把我们要回复的内容深度拷贝到ByteBuf
			ByteBuf content = Unpooled.copiedBuffer("Hello Nettty!!!!",CharsetUtil.UTF_8);
			
			//构建一个Http response
			FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,HttpResponseStatus.OK,content);
			//设置当前内容的类型和长度
			//类型
			response.headers().set(HttpHeaderNames.CONTENT_TYPE,"text/plain");
			//长度
			response.headers().set(HttpHeaderNames.CONTENT_LENGTH,content.readableBytes());
			
			//把相应刷回客户端
			channelHandlerContext.writeAndFlush(response);
		
	    
		
	}

}