private final static int PORT = 8888;
    private static final String HOSTNAME = "13.196.25.157";


    public static void send(String data){
          try (DatagramSocket socket = new DatagramSocket(0)) {
                socket.setSoTimeout(10000);
                InetAddress host = InetAddress.getByName(HOSTNAME);
                byte
 
[] buf = toBytes(data);
                DatagramPacket packet = new DatagramPacket(buf, buf.length,host, PORT);
                socket.send(packet);
                socket.close();
                System.out.println("send alreay");
            } catch (IOException e) {
                System.out.println("error:{}"
 
+e);
            }
    }


    public static byte[] toBytes(String str) {//字串轉為16進位制byte陣列
        if(str == null || str.trim().equals("")) {
            return new byte[0];
        }
        byte[] bytes = new byte[str.length() / 2];
        for(int i = 0; i < str.length() / 2; i++) {
            String subStr = str.substring(i * 2
 
, i * 2 + 2);
            bytes[i] = (byte) Integer.parseInt(subStr, 16);
        }
        return bytes;
    }