我有下面这段code这从openweathermap API检索某些气象数据。所述的AsyncTask类用于该目的。

I have the following piece of code which retrieve some weather data from the openweathermap api. The AsyncTask class is used for that purpose.

public class ForecastFragment extends Fragment {
String imageUrl;
ListView listView;
List<WeatherForecastData> WeatherForecastDataList;
String IMG_URL = "http://api.openweathermap.org/img/w/";
Fragment fragment;

public ForecastFragment() {
    // Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    //Inflate xml view and convert it to a View object
    View rootView = inflater.inflate(R.layout.fragment_forecast, container, false);

    //Initialise ListView.
    listView = (ListView) rootView.findViewById(R.id.listView);
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String temp = WeatherForecastDataList.get(position).getWeatherTemperature();

            Toast.makeText(getActivity(), temp + "° C"+" Have a nice day", Toast.LENGTH_SHORT).show();
        }
    });
    return rootView;
}

//Now we are ready for further processing
@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    setRetainInstance(true);
    if (savedInstanceState == null) {
        if(isOnline()) {
            requestData("http://api.openweathermap.org/data/2.5/forecast/daily?lat=50.09&lon=14.42&cnt=9&&units=metric&mode=json");
        }else{
            Toast.makeText(getActivity(),"There is no internet connection",Toast.LENGTH_SHORT).show();
        }
    }

}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putString("ImageURL", imageUrl);
    super.onSaveInstanceState(savedInstanceState);
}

//We create a MyTask object,and execute the async. thread with the specified url which is shown just above.
private void requestData(String uri) {
    MyTask task = new MyTask();
    task.execute(uri);
}

//AsyncTask that will do the asynchronous threading. It displays the weather's icon,description
//and temperature in the main thread via the OnPostExecute(...) method.
private class MyTask extends AsyncTask<String, String, List<WeatherForecastData>> {

    @Override
    protected void onPreExecute() {
        //Used to initialise Views such as Progress Bars which are not needed for this
        //project.
    }

    @Override
    protected List<WeatherForecastData> doInBackground(String... params) {
        //Read the url,specify the METHOD GET, and store it in content.
        String content = HttpManager.getData(params[0]);
        //JSON parsing of the openweather api's response. It is not hard,but I had to use the
        //debugger quite a lot to make sure that I deserialise the correct JSON values into Strings.
        WeatherForecastDataList = WeatherJSONParser.parseFeed(content);
        //Fetching the url image
        for (WeatherForecastData d : WeatherForecastDataList) {
            try {
                imageUrl = IMG_URL + d.getPhoto();
                InputStream in = (InputStream) new URL(imageUrl).getContent();
                Bitmap bitmap = BitmapFactory.decodeStream(in);
                //Is it deprecated?
                d.setBitmap(bitmap);
                in.close();
            } catch (Exception e) {
                e.printStackTrace();

            }
        }
        return WeatherForecastDataList;
    }

    //WeatherForecastData is the Object that contains all that instances we want to display.
    @Override
    protected void onPostExecute(List<WeatherForecastData> result) {

        if (result == null) {
            Toast.makeText(getActivity(), "There is some wrong,and data can not be displayed", Toast.LENGTH_LONG).show();
            return;
        }
        WeatherForecastDataList = result;
        //Display the ListView.
        WeatherAdapter adapter = new WeatherAdapter(getActivity(), R.layout.weather_row, WeatherForecastDataList);
        listView.setAdapter(adapter);
    }

}

protected boolean isOnline() {
    ConnectivityManager cm = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnectedOrConnecting()) {
        return true;
    } else {
        return false;
    }
}
}

我的问题是，如何让我的异步任务类工作的时候手机rotates.In换句话说，我不希望我的片段被杀害，但存储的天气得到我得到。我看到其他的问题在这里也一样，但我很困惑在这部分。谢谢你。

My question is how to make my async task class to work when phone rotates.In other words,I don't want my Fragment to be killed,but storing the weather get I get. I saw other questions here too,but I am confused in this part. Thank you.

推荐答案

在制作清单配置的变化是不可以推荐的方法来保存片段的实例。

Making config changes in the manifest is not the recommended way to save the instance of the fragment.

相反，你应该保存在容器活动的的onSaveInstanceState（）方法进行覆盖片段的实例。 下面是一个小片段，这将有助于您：

Instead, you should save the instance of the fragment in container activity's onSaveInstanceState() overriden method. Below is a small snippet that will help you:

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    getSupportFragmentManager().putFragment(outState,"fragmentInstanceSaved",getSupportFragmentManager().findFragmentById(R.id.fragment_container));
}

现在，在你的容器活动的onCreate方法检查，如果包是空或不是：

Now, in your container activity's onCreate method check if bundle is null or not:

    if(savedInstanceState!=null){
            Fragment fragment = getSupportFragmentManager().getFragment(savedInstanceState,"fragmentInstanceSaved");
            //recreate your preserved fragment here
        }else{
            //goto ur default activity or fragment....
}