public class Server {

     private ServerBootstrap serverBootstrap;

     private int port;

     public Server(int port) {

         this.port = port;

         serverBootstrap = new ServerBootstrap(

                 new NioServerSocketChannelFactory(Executors.newCachedThreadPool(),

                         Executors.newCachedThreadPool()));

         serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() {

             public ChannelPipeline getPipeline() throws Exception {

                 ChannelPipeline channelPipeline = Channels.pipeline();

                 channelPipeline.addLast("decoder", new StringDecoder());

                 channelPipeline.addLast("encoder", new StringEncoder());

                 channelPipeline.addLast("serverHandler", new ServerHandler());

                 return channelPipeline;

             }

         });

         serverBootstrap.bind(new InetSocketAddress(this.port));

     }

     private class ServerHandler extends SimpleChannelUpstreamHandler {

         @Override

         public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {

             if(e.getMessage() instanceof String) {

                 String message = (String) e.getMessage();

                 System.out.println("Client Send:" + message);

                 e.getChannel().write("Server receive:" + message);

             }

         }

         @Override

         public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {

             System.out.println("A client connected to this server");

             System.out.println("Client:" + e.getChannel().getRemoteAddress());

             e.getChannel().write("******************************\r\n");

             e.getChannel().write("Welcome to connect this server\r\n");

             e.getChannel().write("******************************\r\n");

         }

     }

     public static void main(String args[]) {

         new Server(9999);

     }

 }