Android Studio java.net.MalformedURLException：找不到協議：

Question

我正在從udacity教程開發sunlight應用程序。 我正在上第二課。 當我嘗試運行該應用程序的功能時，出現以下錯誤：

04-29 12:21:13.311  22025-22424/name.company.sunshine.app E/FetchWeatherTask﹕ Error
    java.net.MalformedURLException: Protocol not found: "http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7
            at java.net.URL.<init>(URL.java:176)
            at java.net.URL.<init>(URL.java:125)
            at name.company.sunshine.app.ForecastFragment$FetchWeatherTask.doInBackground(ForecastFragment.java:144)
            at name.company.sunshine.app.ForecastFragment$FetchWeatherTask.doInBackground(ForecastFragment.java:101)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)
04-29 12:21:13.321  22025-22025/name.company.sunshine.app D/AbsListView﹕ unregisterIRListener() is called
04-29 12:21:13.321  22025-22025/name.company.sunshine.app E/ViewRootImpl﹕ sendUserActionEvent() mView == null 

144行是

 URL url = new URL(builtUri.toString());

如果您需要，我將提供整個課程。

還有一點，清單中有這個

<uses-permission android:name="android.permission.INTERNET" /> 

但是當我安裝該應用程序時，它永遠不會征求許可。

這是文件：

package name.company.sunshine.app;

import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.format.Time;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A placeholder fragment containing a simple view.
 */
public class ForecastFragment extends Fragment {

    private ArrayAdapter<String> mForecastAdapter;

    public ForecastFragment() {

    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        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("94043");
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);

        // These two need to be declared outside the try/catch
        // so that they can be closed in the finally block.

        String forecastArray[]  = {
                "Today-Sunny-88/63",
                "Tuesday-Foggy-14/32",
                "Wednesday-Cloudy-22/33"
        };


        List<String> weekForecast = new ArrayList<String>(
                Arrays.asList(forecastArray));


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


        ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
        listView.setAdapter(mForecastAdapter);

        return rootView;
    }

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

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

        @Override
        protected String[] doInBackground(String... params) {

            //If there's no zip code, there's nothing to look up. Verify size of params
            if(params.length == 0){
                return null;
            }

            // 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 avaiable at OWM's forecast API page, at
                // http://openweathermap.org/API#forecast
                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();

                Log.v(LOG_TAG,"Built URI"+builtUri.toString());

                URL url = new URL(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.
                    return 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.
                    return null;
                }
                forecastJsonStr = buffer.toString();
            } catch (IOException e) {
                Log.e(LOG_TAG, "Error ", e);
                // If the code didn't successfully get the weather data, there's no point in attemping
                // to parse it.
                return null;
            } finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException e) {
                        Log.e(LOG_TAG, "Error closing stream", e);
                    }
                }
            }

            try{
                return getWeatherDataFromJson(forecastJsonStr,numDays);
            } catch (JSONException e){
                Log.e(LOG_TAG,e.getMessage(),e);
                e.printStackTrace();
            }
            return null;
        }

        /* The date/time conversion code is going to be moved outside the asynctask later,
        * so for convenience we're breaking it out into its own method now.
                */
        private String getReadableDateString(long time){
            // Because the API returns a unix timestamp (measured in seconds),
            // it must be converted to milliseconds in order to be converted to valid date.
            SimpleDateFormat shortenedDateFormat = new SimpleDateFormat("EEE MMM dd");
            return shortenedDateFormat.format(time);
        }

        /**
         * Prepare the weather high/lows for presentation.
         */
        private String formatHighLows(double high, double low) {
            // For presentation, assume the user doesn't care about tenths of a degree.
            long roundedHigh = Math.round(high);
            long roundedLow = Math.round(low);

            String highLowStr = roundedHigh + "/" + roundedLow;
            return highLowStr;
        }

        /**
         * Take the String representing the complete forecast in JSON Format and
         * pull out the data we need to construct the Strings needed for the wireframes.
         *
         * Fortunately parsing is easy:  constructor takes the JSON string and converts it
         * into an Object hierarchy for us.
         */
        private String[] getWeatherDataFromJson(String forecastJsonStr, int numDays)
                throws JSONException {

            // These are the names of the JSON objects that need to be extracted.
            final String OWM_LIST = "list";
            final String OWM_WEATHER = "weather";
            final String OWM_TEMPERATURE = "temp";
            final String OWM_MAX = "max";
            final String OWM_MIN = "min";
            final String OWM_DESCRIPTION = "main";

            JSONObject forecastJson = new JSONObject(forecastJsonStr);
            JSONArray weatherArray = forecastJson.getJSONArray(OWM_LIST);

            // OWM returns daily forecasts based upon the local time of the city that is being
            // asked for, which means that we need to know the GMT offset to translate this data
            // properly.

            // Since this data is also sent in-order and the first day is always the
            // current day, we're going to take advantage of that to get a nice
            // normalized UTC date for all of our weather.

            Time dayTime = new Time();
            dayTime.setToNow();

            // we start at the day returned by local time. Otherwise this is a mess.
            int julianStartDay = Time.getJulianDay(System.currentTimeMillis(), dayTime.gmtoff);

            // now we work exclusively in UTC
            dayTime = new Time();

            String[] resultStrs = new String[numDays];
            for(int i = 0; i < weatherArray.length(); i++) {
                // For now, using the format "Day, description, hi/low"
                String day;
                String description;
                String highAndLow;

                // Get the JSON object representing the day
                JSONObject dayForecast = weatherArray.getJSONObject(i);

                // The date/time is returned as a long.  We need to convert that
                // into something human-readable, since most people won't read "1400356800" as
                // "this saturday".
                long dateTime;
                // Cheating to convert this to UTC time, which is what we want anyhow
                dateTime = dayTime.setJulianDay(julianStartDay+i);
                day = getReadableDateString(dateTime);

                // description is in a child array called "weather", which is 1 element long.
                JSONObject weatherObject = dayForecast.getJSONArray(OWM_WEATHER).getJSONObject(0);
                description = weatherObject.getString(OWM_DESCRIPTION);

                // Temperatures are in a child object called "temp".  Try not to name variables
                // "temp" when working with temperature.  It confuses everybody.
                JSONObject temperatureObject = dayForecast.getJSONObject(OWM_TEMPERATURE);
                double high = temperatureObject.getDouble(OWM_MAX);
                double low = temperatureObject.getDouble(OWM_MIN);

                highAndLow = formatHighLows(high, low);
                resultStrs[i] = day + " - " + description + " - " + highAndLow;
            }

            for (String s : resultStrs) {
                Log.v(LOG_TAG, "Forecast entry: " + s);
            }
            return resultStrs;

        }
    }

}

現在，刪除“ /"后，我不再有錯誤，但是此行未打印

for (String s : resultStrs) {
                    Log.v(LOG_TAG, "Forecast entry: " + s);
                }

可能無法連接或其他原因。 由於某種原因，我在logCat中看不到任何內容。

Answer 1

問題是您在url的開頭之前轉義了“”，並認為它是Url的一部分。由於"http不是有效的協議，有效值為http https ftp etc 。

final String FORECAST_BASE_URL =  "\"http://api.openweathermap.org/data/2.5/forecast/daily?"; 

應該

final String FORECAST_BASE_URL ="http://api.openweathermap.org/data/2.5/forecast/daily?";

Answer 2

您的URI不是URI。 沒有協議組件。 它需要http：//或您打算使用的其他協議。

從您的FORECAST_BASE_URL中刪除“ /”

final String FORECAST_BASE_URL ="http://api.openweathermap.org/data/2.5/forecast/daily?";