Android开发中如何实现取设备的MAC地址

public static void getMacAddress(final Activity ac, final SimpleCallback callback) {    final WifiManager wm = (WifiManager) ac .getSystemService(Service.WIFI_SERVICE);    // 如果本次开机后打开过WIFI，则能够直接获取到mac信息。立刻返回数据。    WifiInfo info = wm.getConnectionInfo();    if (info != null && info.getMacAddress() != null) {      if (callback != null) {        callback.onComplete(info.getMacAddress());      }      return;    }    // 尝试打开WIFI，并获取mac地址    if (!wm.isWifiEnabled()) {      wm.setWifiEnabled(true);    }    new Thread(new Runnable() {      @Override      public void run() {        int tryCount = 0;        final int MAX_COUNT = 10;        while (tryCount < MAX_COUNT) {          final WifiInfo info = wm.getConnectionInfo();          if (info != null && info.getMacAddress() != null) {            if (callback != null) {              ac.runOnUiThread(new Runnable() {                @Override                public void run() {                  callback.onComplete(info.getMacAddress());                }              });            }            return;          }          SystemClock.sleep(300);          tryCount++;        }        // 未获取到mac地址        if (callback != null) {          callback.onComplete(null);        }      }    }).start();}