Question

我有一个OpenPicus Flypport设备，当通过端口号50000（ UDP ）查询正确的字符串时，会发送JSON字符串。

那不仅仅是信息的强制性

我正在做的是用适当的json查询设备，然后设备回复。但我的Android代码没有收到回复。我已经完成了所有必需的WIFIManager Code和Wifi Permissions。

为了检查Android是否正在播放天气，我写了一个在我的笔记本电脑上运行的java程序。在那里，我发现Android和Flyport设备都在进行通信。

我写了以下代码：

从ANDROID发送

        System.out.println("Sending Flyport");
        FlyportDriver flyDriver = new FlyportDriver();
        sendMulticastFlyport = new Thread(new FlyportSender(set.getFlyportIP() , flyDriver.getDeviceDiscovery()));
        //flyport.getDeviceDiscovery is JSON String. Sending is fine. No problem
        sendMulticastFlyport.start();
        System.out.println("Flyport Send: "+flyDriver.getDeviceDiscovery());
        deviceStartCounter++;

接收ANDROID

private class DeviceSearcher extends AsyncTask<Void, DeviceInformation ,Void>
{
    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
        //TableLayout deviceTable = (TableLayout) findViewById(951357);
        TableRow tr = new TableRow(getApplicationContext());
        LayoutParams layout = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        tr.setLayoutParams(layout);
        TextView tv = new TextView(getApplicationContext());
        tv.setText("Searching...");
        tv.setLayoutParams(layoutParam);
        tv.setTextColor(Color.WHITE);
        tv.setVisibility(View.VISIBLE);
        tr.addView(tv);
        deviceTable.addView(tr);
    }
    @Override
    protected Void doInBackground(Void... arg0)
    {
            new Thread()
            {
                public void run()
                {
                    MulticastSocket socketFlyport=null;
                    try
                    {
                        socketFlyport = new MulticastSocket(50000);
                        socketFlyport.setSoTimeout(1*20*1000);
                        byte[] inBufFlyport = new byte[1024];
                        DatagramPacket inPacketFlyport = new DatagramPacket(inBufFlyport, inBufFlyport.length);

                        while(true)
                        {
                            System.out.println("Listening..."); //Printing
                            socketFlyport.receive(inPacketFlyport); //not receiving

                            String msg = new String(inBufFlyport, 0, inPacketFlyport.getLength());
                            Log.v("Received:","Received Flyport From :" + inPacketFlyport.getAddress() + " Msg : " + msg);
                            String IP = inPacketFlyport.getAddress().toString();
                            System.out.println(Utils.getIPAddress(true));
                            try
                            {
                                System.out.println("Received");
                                DeviceInformation device = new DeviceInformation(3, IP.substring(1), msg, getApplicationContext());
                                publishProgress(device);
                            }
                            catch(Exception e)
                            {
                                System.out.println(e.toString());
                            }
                            Log.v("Received:","Received Flyport From :" + inPacketFlyport.getAddress() + " Msg : " + msg);
                            System.out.println();
                            Thread.sleep(2500);
                        }
                    }
                    catch(Exception e)
                    {
                        Log.v("Exception:","During Receiving Flyport: "+e.toString());
                        publishProgress((DeviceInformation)null);
                    }
                    finally
                    {
                        socketFlyport.close();
                    }
                }
            }.start();
        return null;
    }

如果您将看到我已经打印了一些变量。

Answer 1

是的，正如EJP所说，如果您正在使用多播，那么您需要加入多播组。为了清楚起见，您应该展示您对MulticastLock的使用以及您所请求的Android权限。

话虽如此，似乎Android中的多播支持并不像某些使用可能希望的那样坚固。见http://codeisland.org/2012/udp-multicast-on-android/

我最初认为它是否真的有用，或者可能取决于设备。它不适用于我的Nexus5。见https://code.google.com/p/android/issues/detail?id=51195

但后来我发现重置我的路由器使Android设备开始接收多播帖子。我怀疑Android设备经常出现这种情况。

套接字正在运行但未通过端口接收值

1 个答案: