Android进度对话框方向更改

Question

您好我有这样的问题，我有一个asynctask和进度对话框，当我旋转我的手机失败时，我知道该活动失败了，我们需要创建新的。
所以代码。

public class GetWeather extends AsyncTask<String, Void, WeatherInfo> {
    FragmentActivity activity;
    public GetWeather(FragmentActivity a){
        activity = a;
    }
    static ProgressDialog progressDialog;
    public void showDialog() {
        progressDialog = new ProgressDialog(activity);
        /*Some stuff for dialog*/
        progressDialog.show();
    }
    @Override
    protected void onPreExecute() {
        showDialog();
    }
 protected void onPostExecute(WeatherInfo result){
        progressDialog.dismiss();
}
}

和我的活动课

public class MyActivity extends FragmentActivity implements CityList.OnItemSelectedListener {
    GetWeather weather = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        weather = (GetWeather) getLastCustomNonConfigurationInstance();
        if (weather != null){
            weather.activity = this;
            weather.showDialog();
        }

它失败了。如何修复？谢谢。