Android 判斷目前是否在WIFI網絡下

private static boolean isWifi(Context mContext) {  
    ConnectivityManager connectivityManager = (ConnectivityManager) mContext  
            .getSystemService(Context.CONNECTIVITY_SERVICE);  
    NetworkInfo info= connectivityManager.getActiveNetworkInfo();  
    if (info!= null  
            && info.getType() == ConnectivityManager.TYPE_WIFI) {  
        return true;  
    }  
    return false;  
}