Android Open Source - Sunshine Fetch Weather Task

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright (C) 2014 The Android Open Source Project
 */*  w ww .ja  va 2  s  .  co m*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.sunshine.app;

import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.util.Log;

import com.example.android.sunshine.app.data.WeatherContract;
import com.example.android.sunshine.app.data.WeatherContract.LocationEntry;
import com.example.android.sunshine.app.data.WeatherContract.WeatherEntry;

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.util.Date;
import java.util.Vector;

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

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

    public FetchWeatherTask(Context context) {
        mContext = context;
    }

    /**
     * Helper method to handle insertion of a new location in the weather database.
     *
     * @param locationSetting The location string used to request updates from the server.
     * @param cityName A human-readable city name, e.g "Mountain View"
     * @param lat the latitude of the city
     * @param lon the longitude of the city
     * @return the row ID of the added location.
     */
    private long addLocation(String locationSetting, String cityName, double lat, double lon) {

        // First, check if the location with this city name exists in the db
        Cursor cursor = mContext.getContentResolver().query(
                LocationEntry.CONTENT_URI,
                new String[]{LocationEntry._ID},
                LocationEntry.COLUMN_LOCATION_SETTING + " = ?",
                new String[]{locationSetting},
                null);

        if (cursor.moveToFirst()) {
            int locationIdIndex = cursor.getColumnIndex(LocationEntry._ID);
            return cursor.getLong(locationIdIndex);
        } else {
            ContentValues locationValues = new ContentValues();
            locationValues.put(LocationEntry.COLUMN_LOCATION_SETTING, locationSetting);
            locationValues.put(LocationEntry.COLUMN_CITY_NAME, cityName);
            locationValues.put(LocationEntry.COLUMN_COORD_LAT, lat);
            locationValues.put(LocationEntry.COLUMN_COORD_LONG, lon);

            Uri locationInsertUri = mContext.getContentResolver()
                    .insert(LocationEntry.CONTENT_URI, locationValues);

            return ContentUris.parseId(locationInsertUri);
        }
    }

    /**
     * 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 void getWeatherDataFromJson(String forecastJsonStr, int numDays,
                                            String locationSetting)
            throws JSONException {

        // These are the names of the JSON objects that need to be extracted.

        // Location information
        final String OWM_CITY = "city";
        final String OWM_CITY_NAME = "name";
        final String OWM_COORD = "coord";
        final String OWM_COORD_LAT = "lat";
        final String OWM_COORD_LONG = "lon";

        // Weather information.  Each day's forecast info is an element of the "list" array.
        final String OWM_LIST = "list";

        final String OWM_DATETIME = "dt";
        final String OWM_PRESSURE = "pressure";
        final String OWM_HUMIDITY = "humidity";
        final String OWM_WINDSPEED = "speed";
        final String OWM_WIND_DIRECTION = "deg";

        // All temperatures are children of the "temp" object.
        final String OWM_TEMPERATURE = "temp";
        final String OWM_MAX = "max";
        final String OWM_MIN = "min";

        final String OWM_WEATHER = "weather";
        final String OWM_DESCRIPTION = "main";
        final String OWM_WEATHER_ID = "id";

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

        JSONObject cityJson = forecastJson.getJSONObject(OWM_CITY);
        String cityName = cityJson.getString(OWM_CITY_NAME);
        JSONObject coordJSON = cityJson.getJSONObject(OWM_COORD);
        double cityLatitude = coordJSON.getLong(OWM_COORD_LAT);
        double cityLongitude = coordJSON.getLong(OWM_COORD_LONG);

        Log.v(LOG_TAG, cityName + ", with coord: " + cityLatitude + " " + cityLongitude);

        // Insert the location into the database.
        long locationID = addLocation(locationSetting, cityName, cityLatitude, cityLongitude);

        // Get and insert the new weather information into the database
        Vector<ContentValues> cVVector = new Vector<ContentValues>(weatherArray.length());

        for(int i = 0; i < weatherArray.length(); i++) {
            // These are the values that will be collected.

            long dateTime;
            double pressure;
            int humidity;
            double windSpeed;
            double windDirection;

            double high;
            double low;

            String description;
            int weatherId;

            // 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".
            dateTime = dayForecast.getLong(OWM_DATETIME);

            pressure = dayForecast.getDouble(OWM_PRESSURE);
            humidity = dayForecast.getInt(OWM_HUMIDITY);
            windSpeed = dayForecast.getDouble(OWM_WINDSPEED);
            windDirection = dayForecast.getDouble(OWM_WIND_DIRECTION);

            // Description is in a child array called "weather", which is 1 element long.
            // That element also contains a weather code.
            JSONObject weatherObject =
                    dayForecast.getJSONArray(OWM_WEATHER).getJSONObject(0);
            description = weatherObject.getString(OWM_DESCRIPTION);
            weatherId = weatherObject.getInt(OWM_WEATHER_ID);

            // 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);
            high = temperatureObject.getDouble(OWM_MAX);
            low = temperatureObject.getDouble(OWM_MIN);

            ContentValues weatherValues = new ContentValues();

            weatherValues.put(WeatherEntry.COLUMN_LOC_KEY, locationID);
            weatherValues.put(WeatherEntry.COLUMN_DATETEXT,
                    WeatherContract.getDbDateString(new Date(dateTime * 1000L)));
            weatherValues.put(WeatherEntry.COLUMN_HUMIDITY, humidity);
            weatherValues.put(WeatherEntry.COLUMN_PRESSURE, pressure);
            weatherValues.put(WeatherEntry.COLUMN_WIND_SPEED, windSpeed);
            weatherValues.put(WeatherEntry.COLUMN_DEGREES, windDirection);
            weatherValues.put(WeatherEntry.COLUMN_MAX_TEMP, high);
            weatherValues.put(WeatherEntry.COLUMN_MIN_TEMP, low);
            weatherValues.put(WeatherEntry.COLUMN_SHORT_DESC, description);
            weatherValues.put(WeatherEntry.COLUMN_WEATHER_ID, weatherId);

            cVVector.add(weatherValues);
        }
        if (cVVector.size() > 0) {
            ContentValues[] cvArray = new ContentValues[cVVector.size()];
            cVVector.toArray(cvArray);
            mContext.getContentResolver().bulkInsert(WeatherEntry.CONTENT_URI, cvArray);
        }
    }

    @Override
    protected Void 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;
        }
        String locationQuery = params[0];

        // 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 = 14;

        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();

            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 {
            getWeatherDataFromJson(forecastJsonStr, numDays, locationQuery);
        } catch (JSONException e) {
            Log.e(LOG_TAG, e.getMessage(), e);
            e.printStackTrace();
        }
        // This will only happen if there was an error getting or parsing the forecast.
        return null;
    }
}

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