Android UDP廣播包抓取

Android UDP廣播包抓取

只是貼代碼，以前寫的突然忘記了.

 

 

 

    private WifiManager.MulticastLock multicastLock;    public void init(Context context){         WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);         multicastLock = wifiManager.createMulticastLock(my_net);    }    public byte[] fetchData(){        try {            multicastLock.acquire();            MulticastSocket multicastSocket = new MulticastSocket(55551);            InetAddress group = InetAddress.getByName(224.0.0.2);            multicastSocket.setSoTimeout(3000);            multicastSocket.joinGroup(group);            multicastSocket.setLoopbackMode(true);            byte[] buffer = new byte[512];            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);            multicastSocket.receive(packet);            return buffer;        } catch (Exception e) {            e.printStackTrace();        } finally {            multicastLock.release();//一定要釋放        }        return null;    }