Receive message from server netty nio java

Question

I am trying to figure out how can i create a chat using netty nio server and client code found from here . What I want actually is to figure out how exactly can I use the received messages from both client and server. I have found in the server the following code in the server which types a received message:

 public class EchoClientHandler extends ChannelInboundHandlerAdapter {

   public String message;
   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
      System.out.println("Got reply: " + msg.toString().trim());
      message = msg.toString().trim();
      ctx.disconnect();
    }
    // How to store the message variable and use it from my main function?????
 }

This code stands for the echoClient:

public class EchoClient {

  public String host;
  public int port;


  public EchoClient(String host, int port) {

     this.host = host;
     this.port = port;
  }

  public void send(String msg) throws InterruptedException {

      EventLoopGroup eventGroup = new NioEventLoopGroup();

      Bootstrap bootstrap = new Bootstrap();
      bootstrap.group(eventGroup)
            .remoteAddress(host, port)
            .channel(NioSocketChannel.class) // TCP server socket
            .handler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(
                            // break stream into "lines"
                            new LineBasedFrameDecoder(EchoServerHandler.LINE_MAX, false, true),
                            new StringDecoder(CharsetUtil.UTF_8),
                            new StringEncoder(CharsetUtil.UTF_8),
                            new EchoClientHandler()
                    );
                }
            });

      ChannelFuture f = bootstrap.connect().sync();
      System.out.println("Connected!");
      f.channel().writeAndFlush(msg).sync();
      System.out.print("Sent: " + msg);
      f.channel().closeFuture().sync();
      eventGroup.shutdownGracefully().sync();
      System.out.println("Done.");
  }

  public static void main(String[] args) throws InterruptedException {

      EchoClientHandler temp = new EchoClientHandler(); //how can i have access to this variable and the returned message?
      String host ="127.0.0.1";
      int port = 8080;
      EchoClient client = new EchoClient(host, port);
      client.send("Hello world!\n");
      temp.message?
  }
}

In the code here there is a printing message, however how can the Object msg is connected with the received message? And how can i use it when i want?

EDIT: public String message in the channelRead has a value however, inside the main is null. How can I pass correctly the value? Guess that the EchoCLientHandler and EchoClient are different threads than my main function in EchoClient. However, is there a way to read from my main function the received message that got from EchoClientHandler?

Answer 1

You used the StringEncoder to encode the incoming ByteBuf buffer, StringDecoder to decode the outgoing message. You may want to deal with it similar with bgTaskGroup.submit(new Sleeper(sleepMillis, ctx.channel())); in BGTaskServerHandler handler.