请写一个netty websocket

好的，以下是一个使用 Netty 实现 WebSocket 服务器的示例代码：

public class WebSocketServer {
    public static void main(String[] args) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap()
                    .group(group)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new HttpServerCodec());
                            pipeline.addLast(new HttpObjectAggregator(65536));
                            pipeline.addLast(new WebSocketServerProtocolHandler("/chat"));
                            pipeline.addLast(new TextWebSocketFrameHandler());
                        }
                    });

            ChannelFuture future = bootstrap.bind(8080).sync();
            future.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }

    private static class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
        private final List<Channel> channels = new ArrayList<>();

        @Override
        protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
            String text = msg.text();
            System.out.println("Received message: " + text);

            for (Channel channel : channels) {
                channel.writeAndFlush(new TextWebSocketFrame("Server: " + text));
            }
        }

        @Override
        public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
            channels.add(ctx.channel());
        }

        @Override
        public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
            channels.remove(ctx.channel());
        }
    }
}

这个示例代码启动一个 WebSocket 服务器，并监听本地的 8080 端口。当有新的 WebSocket 连接建立时，服务器会将连接加入到一个列表中，当有消息发送到服务器时，服务器会将消息转发给所有连接。