如何将Android设备与3D打印机连接

Question

我将此方法称为Java桌面应用程序，它可以正常工作，但是当我在android应用程序中调用它时，该方法无法正常工作。请帮我什么问题。我被添加了权限 在清单文件中。

这是错误：

W / System.err：android.os.NetworkOnMainThreadException

private static String sendmessage(String host, String sendMessage){
    Socket socket=new Socket();
    String getmessage="";

    try
    {
        int port = 80;
        InetAddress address = InetAddress.getByName(host);
        socket = new Socket(address, port);

        //Send the message to the server
        OutputStream os = socket.getOutputStream();
        OutputStreamWriter osw = new OutputStreamWriter(os);
        BufferedWriter bw = new BufferedWriter(osw);



        bw.write(sendMessage);
        bw.flush();

        //Get the return message from the server
        InputStream is = socket.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        getmessage = br.readLine();

    }
    catch (Exception exception)
    {
        exception.printStackTrace();
    }
    finally
    {
        //Closing the socket
        try
        {
            socket.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

    return getmessage;
}