Java tutorial
/* * Copyright (C) 2014 The Android Open Source Project * * 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.qualisys.parkassist; import android.content.ContentUris; import android.content.ContentValues; import android.content.Context; import android.content.SharedPreferences; import android.database.Cursor; import android.net.Uri; import android.os.AsyncTask; import android.preference.PreferenceManager; import android.util.Log; 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.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; } /* 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. Date date = new Date(time * 1000); SimpleDateFormat format = new SimpleDateFormat("E, MMM d"); return format.format(date).toString(); } /** * Prepare the weather high/lows for presentation. */ private String formatHighLows(double high, double low) { // Data is fetched in Celsius by default. // If user prefers to see in Fahrenheit, convert the values here. // We do this rather than fetching in Fahrenheit so that the user can // change this option without us having to re-fetch the data once // we start storing the values in a database. SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(mContext); String unitType = sharedPrefs.getString(mContext.getString(R.string.preferences_unit_system_key), mContext.getString(R.string.preferences_unit_metric_system_value)); if (unitType.equals(mContext.getString(R.string.preferences_unit_imperial_system_value))) { high = (high * 1.8) + 32; low = (low * 1.8) + 32; } else if (!unitType.equals(mContext.getString(R.string.preferences_unit_metric_system_value))) { Log.d(LOG_TAG, "Unit type not found: " + unitType); } // 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. * <p/> * 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, 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); Vector<ContentValues> cVVector = new Vector<ContentValues>(weatherArray.length()); String[] resultStrs = new String[numDays]; 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); String highAndLow = formatHighLows(high, low); String day = getReadableDateString(dateTime); resultStrs[i] = day + " - " + description + " - " + highAndLow; } ContentValues[] contentValuesToBulkInsert = new ContentValues[cVVector.size()]; cVVector.toArray(contentValuesToBulkInsert); /* mContext.getContentResolver().bulkInsert(WeatherEntry.CONTENT_URI, contentValuesToBulkInsert); */ return resultStrs; } @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; } private Long addLocation(String locationSetting, String cityName, double lat, double lon) { Log.v(LOG_TAG, "inserting " + cityName + ", with coord: " + lat + ", " + lon); Long existingId = getLocationIdByLocationSetting(locationSetting); if (existingId == null) { Log.v(LOG_TAG, "Didn't find it in the database, inserting now!"); ContentValues locationValues = new ContentValues(); /* locationValues.put(WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING, locationSetting); locationValues.put(WeatherContract.LocationEntry.COLUMN_CITY_NAME, cityName); locationValues.put(WeatherContract.LocationEntry.COLUMN_LAT, lat); locationValues.put(WeatherContract.LocationEntry.COLUMN_LON, lon); Uri locationInsertUri = mContext.getContentResolver() .insert(WeatherContract.LocationEntry.CONTENT_URI, locationValues); return ContentUris.parseId(locationInsertUri); */ } else { return existingId; } return null; } private Long getLocationIdByLocationSetting(String locationSetting) { /* // A cursor is your primary interface to the query results. Cursor cursor = mContext.getContentResolver().query( WeatherContract.LocationEntry.CONTENT_URI, new String[]{WeatherContract.LocationEntry._ID}, // leaving "columns" null just returns all the columns. WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING + " = ? ", // cols for "where" clause new String[]{locationSetting}, // values for "where" clause null // sort order ); if (cursor.moveToFirst()) { Log.v(LOG_TAG, "Found it in the database!"); int locationIdIndex = cursor.getColumnIndex(WeatherContract.LocationEntry._ID); return cursor.getLong(locationIdIndex); }*/ return null; } }