Netty客户端，连接到服务器后停止

Question

I just started with Netty .

Currently I am trying to send an Object to a Server. I wrote some client in Java , and it's working fine. I also wrote an Android App that receives messages from a server. I tried to add some code for handling Object s to the Client part, but there is a problem.

It connects, but it's not sending messages. The Server is the same, so is the Object . Manifest is ok. I've tried multiple times to lunch Java client and Android client. Everything is working for Java . I am desperate already.

Here is my code

Client

public final class ObjectEchoClient {

    public static ChannelHandlerContext ctx;
    static final String HOST = System.getProperty("host", "192.168.0.101");
    static final int PORT = Integer.parseInt(System.getProperty("port", "8080"));


    public static void startClient() throws Exception {


        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
             .channel(NioSocketChannel.class)
             .option(ChannelOption.SO_BACKLOG, 128)
             .option(ChannelOption.SO_KEEPALIVE, true) // (4)
             .handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ChannelPipeline p = ch.pipeline();

                    p.addLast(
                            new ObjectEncoder(),
                            new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
                            new ObjectEchoClientHandler());
                }
             });

            // Start the connection attempt.
            b.connect(HOST, PORT).sync().channel().closeFuture().sync();


        } finally {
            group.shutdownGracefully();
        }
    }
}

Android MainActivity

public class MainActivity extends Activity {
    public static UnixTime m;
    public static int id = 12345678;
    public static ChannelHandlerContext ctx;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

        socketTest();

        final Button btn1 = (Button)findViewById(R.id.button1);


        btn1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                try {
                    //*
                    if(ObjectEchoClient.ctx != null)
                    { 
                        Package p = new Package();
                        p.setId(id);
                        ObjectEchoClient.ctx.writeAndFlush(p);
                    }
                    else
                    {
                        Log.e("test", "off");
                    }
                    //*/
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        });

    }
public static void socketTest()
    {
        new Thread (new Runnable() {

            @Override
            public void run() {
                try {
                    ObjectEchoClient.startClient();

                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }   
            }}).start();

    }

PS If I add some message to the handler at the channelActive method in the ObjectEchoClientHandler() , it will be sent. but I need to send it when I will need to.

PPS Hendler

public class ObjectEchoClientHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) {

        ObjectEchoClient.ctx = ctx;

    }



    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
       ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

Answer 1

I am a bit rusty here but when you call:

b.connect(HOST, PORT).sync().channel().closeFuture().sync();

are you not closing the channel as soon as it's opened ?

Sending a message on channel active is sending during the brief period the channel is connected, no ?

I'm still a netty3 diehard but looking at the 5 samples, to connect you want to:

ChannelFuture f = b.connect(HOST, PORT).sync();

And then later, to stop the client:

f.channel().closeFuture().sync();

Answer 2

So the problem was in the writeAndFlush(); method. For Android it's not flushing properly data. So You need to flush it, once again.

ObjectEchoClient.ctx.writeAndFlush(p);
ctx.flush();