使用Netty构建TCP和UDP服务器和客户端

Netty是一个基于Java NIO实现的网络通信框架，提供了高性能、低延迟的网络通信能力。使用Netty构建TCP和UDP服务器和客户端非常简单，下面是一个简单的示例代码：

1. 构建TCP服务器

   public class TcpServer {
       private final int port;
   
       public TcpServer(int port) {
           this.port = port;
       }
   
       public void start() throws Exception {
           EventLoopGroup group = new NioEventLoopGroup();
           try {
               ServerBootstrap b = new ServerBootstrap();
               b.group(group)
                .channel(NioServerSocketChannel.class)
                .localAddress(new InetSocketAddress(port))
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(new TcpServerHandler());
                    }
                });
   
               ChannelFuture f = b.bind().sync();
               f.channel().closeFuture().sync();
           } fi