Android 8.1 獲取wifi mac地址方法

安卓8.1更新了獲取WIFI地址的方法，使用之前的方法獲取不到地址

    private String getWifiMacAddress() {
        String str = "";
        String macSerial = "";
        try {
            Process pp = Runtime.getRuntime().exec(
                    "cat /sys/class/net/wlan0/address ");
            InputStreamReader ir = new InputStreamReader(
                    pp.getInputStream());
            LineNumberReader input = new LineNumberReader(ir);
            for (; null != str; ) {
                str = input.readLine();
                if (str != null) {
                    macSerial = str.trim();// 去空格
                    break;
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return macSerial;
    }

更新使用以下方法即可獲取到wifi地址，我自己遇到的Android 8.1機型測試可以獲取

    private String getWifiMacAddress() {
        String defaultMac = "02:00:00:00:00:00";
        try {
            List<NetworkInterface> interfaces = Collections
                    .list(NetworkInterface.getNetworkInterfaces());
            for (NetworkInterface ntwInterface : interfaces) {

                if (ntwInterface.getName().equalsIgnoreCase("p2p0")) {
                    byte[] byteMac = ntwInterface.getHardwareAddress();
                    if (byteMac == null) {
                        // return null;
                    }
                    StringBuilder strBuilder = new StringBuilder();
                    for (int i = 0; i < byteMac.length; i++) {
                        strBuilder.append(String
                                .format("%02X:", byteMac[i]));
                    }

                    if (strBuilder.length() > 0) {
                        strBuilder.deleteCharAt(strBuilder.length() - 1);
                    }

                    return strBuilder.toString();
                }

            }
        } catch (Exception e) {
//             Log.d(TAG, e.getMessage());
        }
        return defaultMac;
    }