Dart连接socket(netty)

Client:

import 'dart:io';
import 'dart:async';
import 'dart:convert' show utf8;

Socket socket;

void main() {
  Socket.connect("localhost", 8888).then((Socket sock) {
    socket = sock;
    socket.listen(dataHandler,
        onError: errorHandler,
        onDone: doneHandler,
        cancelOnError: false);
  }).catchError((AsyncError e) {
    print("Unable to connect: $e");
  });
  //发报文
  stdin.listen((data) => socket.write( utf8.decode(data)));
}

//接收报文
void dataHandler(data){
  print(utf8.decode(data));
}

void errorHandler(error, StackTrace trace){
  print(error);
}

void doneHandler(){
  socket.destroy();
}

Server:

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class MyMain {
    public static void main(String[] args) {

        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap
                .group(new NioEventLoopGroup(),new NioEventLoopGroup())
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<NioSocketChannel>() {
                    protected void initChannel(NioSocketChannel ch) {
                        ch.pipeline().addLast(new StringDecoder());
                        ch.pipeline().addLast(new StringEncoder());
                        ch.pipeline().addLast(new MyHandler());
                    }
                }).bind(8888).addListener((e)->{
                        if(e.isSuccess()){
                            System.out.println("server is successfully");
                        }
                    });

    }

}


class MyHandler extends SimpleChannelInboundHandler<String> {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("有新连接");
        super.channelActive(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
//        super.exceptionCaught(ctx, cause);
    }

    protected void channelRead0(ChannelHandlerContext ctx, String msg){
        System.out.println("有人说:"+msg);
        ctx.writeAndFlush("你说'"+msg+"'?");
    }
}