＆＃34; java.io.IOException：未发现身份验证问题＆＃34;从Android

Question

以下是我尝试从开放天气api获取json数组以根据udacity课程构建应用程序时获得的异常。

com.example.android.weatherapp E/PlaceholderFragment: Error 
java.io.IOException: No authentication challenges found
    at libcore.net.http.HttpURLConnectionImpl.getAuthorizationCredentials(HttpURLConnectionImpl.java:427)
    at libcore.net.http.HttpURLConnectionImpl.processAuthHeader(HttpURLConnectionImpl.java:407)
    at libcore.net.http.HttpURLConnectionImpl.processResponseHeaders(HttpURLConnectionImpl.java:356)
    at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:292)
    at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
    at com.example.android.weatherapp.ForecastFragment$FetchWeatherTask.doInBackground(ForecastFragment.java:136)
    at com.example.android.weatherapp.ForecastFragment$FetchWeatherTask.doInBackground(ForecastFragment.java:85)
    at android.os.AsyncTask$2.call(AsyncTask.java:287)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
    at java.lang.Thread.run(Thread.java:856)

片段类的代码在这里：

public class ForecastFragment extends Fragment {

    public ForecastFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Add this line in order for this fragment to handle menu events.
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.forecastfragment, menu);
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_refresh) {
            FetchWeatherTask weatherTask = new FetchWeatherTask();
            //weatherTask.execute();
            weatherTask.execute("94043");

            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        ArrayList<String> forcastentry = new ArrayList<String>();
        forcastentry.add("Today-sunny-88/63");
        forcastentry.add("Today-sunny-88/63");
        forcastentry.add("Today-sunny-88/63");
        forcastentry.add("Today-sunny-88/63");
        forcastentry.add("Today-sunny-88/63");
        forcastentry.add("Today-sunny-88/63");

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),
                R.layout.list_item_forecast, R.id.list_item_forecast_textview, forcastentry);

        View rootView = inflater.inflate(R.layout.fragment_main, container, false);

        ListView listview = (ListView) rootView.findViewById(R.id.listview_forecast);
        listview.setAdapter(adapter);

//        return inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
    }

    public class FetchWeatherTask  extends AsyncTask<String,Void,Void> {

        public final String LOG_TAG = FetchWeatherTask.class.getSimpleName();

        @Override
        public Void doInBackground(String... params ) {


            // These two need to be declared outside the try/catch
// so that they can be closed in the finally block.
            HttpURLConnection urlConnection = null;
            BufferedReader reader = null;

// Will contain the raw JSON response as a string.
            String forecastJsonStr = null;
            String format = "json";
            String units = "metric";
            int numDays = 7;


            try {
                // Construct the URL for the OpenWeatherMap query
                // Possible parameters are available at OWM's forecast API page, at
                // http://openweathermap.org/API#forecast
                //URL url = new URL("http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7");
//

                final String FORECAST_BASE_URL =
                        "http://api.openweathermap.org/data/2.5/forecast/daily?";
                final String QUERY_PARAM = "q";
                final String FORMAT_PARAM="mode";
                final String UNITS_PARAM="units";
                final String DAYS_PARAM="cnt";

                Uri builtUri = Uri.parse(FORECAST_BASE_URL).buildUpon()
                        .appendQueryParameter(QUERY_PARAM,params[0])
                        .appendQueryParameter(FORMAT_PARAM,format)
                        .appendQueryParameter(UNITS_PARAM,units)
                        .appendQueryParameter(DAYS_PARAM,Integer.toString(numDays))
                        .build();

                URL url = new URL(builtUri.toString());
                Log.v("check", "Built URI " + builtUri.toString());


                // Create the request to OpenWeatherMap, and open the connection
                urlConnection = (HttpURLConnection) url.openConnection();
                urlConnection.setRequestMethod("GET");
                urlConnection.connect();

                // Read the input stream into a String
                InputStream inputStream = urlConnection.getInputStream();
                StringBuffer buffer = new StringBuffer();
                if (inputStream == null) {
                    // Nothing to do.
                    forecastJsonStr = null;
                }
                reader = new BufferedReader(new InputStreamReader(inputStream));

                String line;
                while ((line = reader.readLine()) != null) {
                    // Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
                    // But it does make debugging a *lot* easier if you print out the completed
                    // buffer for debugging.
                    buffer.append(line + "\n");
                }

                if (buffer.length() == 0) {
                    // Stream was empty.  No point in parsing.
                    forecastJsonStr = null;
                }
                forecastJsonStr = buffer.toString();
                Log.v("Forecast","Forecast Json String"+forecastJsonStr);
            } catch (IOException e) {
                Log.e("PlaceholderFragment", "Error ", e);
                // If the code didn't successfully get the weather data, there's no point in attempting
                // to parse it.
                forecastJsonStr = null;
            } finally{
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException e) {
                        Log.e("PlaceholderFragment", "Error closing stream", e);
                    }
                }
            }
            return null;
        }
    }
}