How to connect a mobile application from your android mobile device to your laptop server using sockets?

Question

I have a very simple Java server that runs on my laptop. On the other side i have my Tablet with also a very simple client to conect to my server but it is not working. Both are running on the same wireless network.

Sample of the Server ServerSocket serverSocket = null; Socket socket = null; DataInputStream dataInputStream = null; DataOutputStream dataOutputStream = null;

    try {
        serverSocket = new ServerSocket(8888);
        System.out.println("Listening :8888");
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    while(true){
        try {
            socket = serverSocket.accept();
            dataInputStream = new DataInputStream(socket.getInputStream());
            dataOutputStream = new DataOutputStream(socket.getOutputStream());
            System.out.println("ip: " + socket.getInetAddress());
            System.out.println("message: " + dataInputStream.readUTF());
            dataOutputStream.writeUTF("Hello!");

Simple client code:

mysock = new Socket(server_adress, port_number);

Ive tried setting the manifest WIFI permissions. Tried shutting down the computer firewalls. Is there something i should know regarding how the wireless conection works that might be blocking the conection?

Thanks in advance

Answer 1

You need to set permission for INTERNET.

<uses-permission android:name="android.permission.INTERNET"></uses-permission>

Client side:

String adresaServer = "192.168.4.120";

        int PORT = 8095;
        Socket socket = null;

        DataInputStream in = null;

        try {
            socket = new Socket();
            SocketAddress adr = new InetSocketAddress(adresaServer, PORT);
            socket.connect(adr, 1500);

            out = new DataOutputStream(socket.getOutputStream());
            in = new DataInputStream(socket.getInputStream());
            out.flush();
        } catch (SocketTimeoutException e) {
            System.err.println(" Error at CONNECTINGG: \n" + e);

        } catch (UnknownHostException e) {
            System.err.println(" Serverul nu poate fi gasit \n" + e);
            System.exit(1);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        }
        out.writeFloat(sensors.getValueGyroZ());
            } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (Exception e) {

                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

Server Side:

ServerSocket serverSocket = null;

        try {
            serverSocket = new ServerSocket(PORT);
            serverSocket.setSoTimeout(1600000);

            System.out.println(" Waiting a client ... ");
            Socket socket = serverSocket.accept();
            int i = 0;
            DataOutputStream out = new DataOutputStream(
                    socket.getOutputStream());



            while (true) {


                DataInputStream in = new DataInputStream(
                        socket.getInputStream());



            System.out.println(String.valueOf(in.readFloat()));

            }

        } catch (IOException e) {
            System.err.println(" Eroare IO \n" + e);


        } finally {
            try {
                serverSocket.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }