我使用以下代码在ServerManager类中启动服务器：

gpcmServer = new GpcmServer(port);

gpspServer = new GpspServer(port);

在这些类中,我按如下方式启动服务器：

public GpspServer(int port) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup,workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            // Add the server handler and its decoder
                            ch.pipeline().addLast(new GpspDecoder(),new GpspServerHandler());
                        }
                    })
                    .option(ChannelOption.SO_BACKLOG,128)
                    .childOption(ChannelOption.SO_KEEPALIVE,true);

            // Bind and start to accept incoming connections.
            bindFuture = bootstrap.bind(port).sync();

            bindFuture.channel().closeFuture();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }

但是,当我不调用closeFuture().sync()时,我无法连接到服务器.当我将.sync()添加到bindFuture.channel().closeFuture()时,我可以连接到服务器.我如何继续这样做,仍然使服务器工作？