Android客户端套接字直到write（）才连接

Question

I have a problem with socket communication in Android app. After client call to Socket.connect(adr,time) nothing happens on server (written in C) side (accept() not returning new socket). Only when I write something to socket on the client side, communication starts and server sends welcome message. When I am using telnet everything works fine. Can somebody please explain to me why connect() method not connects until first write()?

So here is some explanation of problematic client code. Communication starts after clicking this button in main activity:

  private View.OnClickListener buttonConnectOnClickListener = new View.OnClickListener() {
    public void onClick(View v){

            commTask = new TCPComm();
            commTask.execute();
      }
};

It executes new AsyncTask to communicate with server:

 public class TCPComm extends AsyncTask<Void, byte[], Boolean> {
    Socket commSock;
    InputStream netInStream;
    OutputStream netOutStream;
    BufferedReader inFromServer;


    @Override
    protected void onPreExecute() {
        outputText("Connecting to LightServer");

    }

    @Override
    protected Boolean doInBackground(Void... params) {
        boolean result = false;
        String srvResponse;
        try {
            SocketAddress sockaddr = new InetSocketAddress("XXX.XXX.XXX.XXX", XXXX);
            commSock = new Socket();
            commSock.setTcpNoDelay(true);
            commSock.connect(sockaddr, 5000);

                if (commSock.isConnected()) {

                netInStream = commSock.getInputStream();
                netOutStream = commSock.getOutputStream();

                inFromServer = new BufferedReader(new InputStreamReader(netInStream));
                while((srvResponse = inFromServer.readLine()) != null){
                    byte[] responseArray = srvResponse.getBytes();
                    publishProgress(responseArray);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
            result = true;
        } finally {
            closeSocket();
        }
        return result;
    }


    @Override
    protected void onProgressUpdate(byte[]... values) {

        if (values.length > 0) {
            if (Arrays.equals(values[0],msgPIN)) {
                pin = pinEdit.getText().toString().trim()+"#";
                SendResponse(pin);

            }

            if (Arrays.equals(values[0],msgCOM)) {
                authenticated = true;
                relaySwitch.setEnabled(true);

            }

        }
    }

}

But this task does not make connection to server. Only when I write something to socket connection is established and server sends first message. I wrote simple java app only with this fragment of AsyncTask:

SocketAddress sockaddr = new InetSocketAddress("XXX.XXX.XXX.XXX", XXXX);
commSock = new Socket();
commSock.setTcpNoDelay(true);
commSock.connect(sockaddr, 5000);

and it connects with no problems so i think that this issue is related to android and processing of AsyncTask

Answer 1

:DI have found a solution. Everything works fine on mobile. On emulator this connections are broken. I think that this is related to NAT. In my test environment client running on emulator connects to server on LAN. Maybe someone can explain how to setup adb to work properly with this kind of connections?