获取设备的mac地址可靠的方法

参考自：http://www.open-open.com/lib/view/open1433406847322.html

　　/**
     * 获取设备的mac地址
     *
     * @param ac
     * @param callback
     *            成功获取到mac地址之后会回调此方法
     */
    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();
    }

public interface SimpleCallback {
    void onComplete(String result);
}