android系统6.0之后，对mac地址的获取添加了权限，按照普通的方法获取如下：

WifiManager  wifiMan = (WifiManager)context.getSystemService(Context.WIFI_SERVICE) ;
WifiInfo wifiInf = wifiMan.getConnectionInfo();
return wifiInf.getMacAddress();

但是这种情况，获取到的mac地址都是：02:00:00:00:00:00，看来就需要另一种方法来获取mac地址：

private static final String marshmallowMacAddress = "02:00:00:00:00:00";
  private static final String fileAddressMac = "/sys/class/net/wlan0/address";

  public static String getAdresseMAC(Context context) {
    WifiManager wifiMan = (WifiManager)context.getSystemService(Context.WIFI_SERVICE) ;
    WifiInfo wifiInf = wifiMan.getConnectionInfo();

    if(wifiInf !=null && marshmallowMacAddress.equals(wifiInf.getMacAddress())){
      String result = null;
      try {
        result= getAdressMacByInterface();
        if (result != null){
          return result;
        } else {
          result = getAddressMacByFile(wifiMan);
          return result;
        }
      } catch (IOException e) {
        Log.e("MobileAccess", "Erreur lecture propriete Adresse MAC");
      } catch (Exception e) {
        Log.e("MobileAcces", "Erreur lecture propriete Adresse MAC ");
      }
    } else{
      if (wifiInf != null && wifiInf.getMacAddress() != null) {
        return wifiInf.getMacAddress();
      } else {
        return "";
      }
    }
    return marshmallowMacAddress;
  }

接下来，来分析一下其中两个重要的方法
1.getAdressMacByInterface()

 private static String getAdressMacByInterface(){
    try {
      List<NetworkInterface> all = Collections.list(NetworkInterface.getNetworkInterfaces());
      for (NetworkInterface nif : all) {
        if (nif.getName().equalsIgnoreCase("wlan0")) {
          byte[] macBytes = nif.getHardwareAddress();
          if (macBytes == null) {
            return "";
          }

          StringBuilder res1 = new StringBuilder();
          for (byte b : macBytes) {
            res1.append(String.format("%02X:",b));
          }

          if (res1.length() > 0) {
            res1.deleteCharAt(res1.length() - 1);
          }
          return res1.toString();
        }
      }

    } catch (Exception e) {
      Log.e("MobileAcces", "Erreur lecture propriete Adresse MAC ");
    }
    return null;
  }

2.getAddressMacByFile(wifiMan)

  private static String getAddressMacByFile(WifiManager wifiMan) throws Exception {
    String ret;
    int wifiState = wifiMan.getWifiState();

    wifiMan.setWifiEnabled(true);
    File fl = new File(fileAddressMac);
    FileInputStream fin = new FileInputStream(fl);
    ret = crunchifyGetStringFromStream(fin);
    fin.close();

    boolean enabled = WifiManager.WIFI_STATE_ENABLED == wifiState;
    wifiMan.setWifiEnabled(enabled);
    return ret;
  }

  private static String crunchifyGetStringFromStream(InputStream crunchifyStream) throws IOException {
    if (crunchifyStream != null) {
      Writer crunchifyWriter = new StringWriter();

      char[] crunchifyBuffer = new char[2048];
      try {
        Reader crunchifyReader = new BufferedReader(new InputStreamReader(crunchifyStream, "UTF-8"));
        int counter;
        while ((counter = crunchifyReader.read(crunchifyBuffer)) != -1) {
          crunchifyWriter.write(crunchifyBuffer, 0, counter);
        }
      } finally {
        crunchifyStream.close();
      }
      return crunchifyWriter.toString();
    } else {
      return "No Contents";
    }
  }