Android:根據上下文Context獲取Activity

根據Context獲取Activity：

private Activity getActivity() {
    Context context = getContext();
    while (!(context instanceof Activity) && context instanceof ContextWrapper) {
        context = ((ContextWrapper) context).getBaseContext();
}

if (context instanceof Activity) {
return (Activity) context;
}
throw new FacebookException("Unable to get Activity.");
}