/Sky/Sky/src/org/jsharkey/sky/WebserviceHelper.java
Java | 416 lines | 265 code | 65 blank | 86 comment | 57 complexity | b85a699ae96a30babf986443a2700d60 MD5 | raw file
1/* 2 * Copyright (C) 2009 Jeff Sharkey, http://jsharkey.org/ 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package org.jsharkey.sky; 18 19import java.io.IOException; 20import java.io.InputStreamReader; 21import java.io.Reader; 22import java.io.StringReader; 23import java.util.ArrayList; 24import java.util.Collections; 25import java.util.Comparator; 26import java.util.HashMap; 27import java.util.List; 28import java.util.Map; 29 30import org.apache.http.HttpEntity; 31import org.apache.http.HttpResponse; 32import org.apache.http.StatusLine; 33import org.apache.http.client.HttpClient; 34import org.apache.http.client.methods.HttpGet; 35import org.apache.http.impl.client.DefaultHttpClient; 36import org.jsharkey.sky.ForecastProvider.AppWidgets; 37import org.jsharkey.sky.ForecastProvider.AppWidgetsColumns; 38import org.jsharkey.sky.ForecastProvider.Forecasts; 39import org.jsharkey.sky.ForecastProvider.ForecastsColumns; 40import org.xmlpull.v1.XmlPullParser; 41import org.xmlpull.v1.XmlPullParserException; 42import org.xmlpull.v1.XmlPullParserFactory; 43 44import android.content.ContentResolver; 45import android.content.ContentValues; 46import android.content.Context; 47import android.database.Cursor; 48import android.net.Uri; 49import android.text.Editable; 50import android.text.SpannableStringBuilder; 51import android.text.TextUtils; 52import android.text.format.DateUtils; 53import android.text.format.Time; 54import android.util.Log; 55import android.util.TimeFormatException; 56 57/** 58 * Helper class to handle querying a webservice for forecast details and parsing 59 * results into {@link ForecastProvider}. 60 */ 61public class WebserviceHelper { 62 private static final String TAG = "ForcastHelper"; 63 64 private static final String[] PROJECTION_APPWIDGET = { 65 AppWidgetsColumns.LAT, 66 AppWidgetsColumns.LON, 67 }; 68 69 private static final int COL_LAT = 0; 70 private static final int COL_LON = 1; 71 72 static final boolean FAKE_DATA = false; 73 74 static final String WEBSERVICE_URL = "http://www.weather.gov/forecasts/xml/sample_products/browser_interface/ndfdBrowserClientByDay.php?&lat=%f&lon=%f&format=24+hourly&numDays=%d"; 75 76 /** 77 * Timeout to wait for webservice to respond. Because we're in the 78 * background, we don't mind waiting for good data. 79 */ 80 static final long WEBSERVICE_TIMEOUT = 30 * DateUtils.SECOND_IN_MILLIS; 81 82 /** 83 * Various XML tags present in the response. 84 */ 85 private static final String TAG_TEMPERATURE = "temperature"; 86 private static final String TAG_WEATHER = "weather"; 87 private static final String TAG_POP = "probability-of-precipitation"; 88 private static final String TAG_HAZARDS = "hazards"; 89 private static final String TAG_WEATHER_CONDITIONS = "weather-conditions"; 90 private static final String TAG_HAZARD = "hazard"; 91 private static final String TAG_LAYOUT_KEY = "layout-key"; 92 private static final String TAG_START_VALID_TIME = "start-valid-time"; 93 private static final String TAG_VALUE = "value"; 94 private static final String TAG_HAZARDTEXTURL = "hazardTextURL"; 95 private static final String TAG_MOREWEATHERINFORMATION = "moreWeatherInformation"; 96 97 /** 98 * Various XML attributes present in the response. 99 */ 100 private static final String ATTR_TIME_LAYOUT = "time-layout"; 101 private static final String ATTR_TYPE = "type"; 102 private static final String ATTR_WEATHER_SUMMARY = "weather-summary"; 103 private static final String ATTR_PHENOMENA = "phenomena"; 104 private static final String ATTR_SIGNIFICANCE = "significance"; 105 106 private static final String TYPE_MAXIMUM = "maximum"; 107 private static final String TYPE_MINIMUM = "minimum"; 108 109 private static final String EXAMPLE_RESPONSE = "<?xml version=\"1.0\"?><dwml version=\"1.0\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:noNamespaceSchemaLocation=\"http://www.nws.noaa.gov/forecasts/xml/DWMLgen/schema/DWML.xsd\"><head><product srsName=\"WGS 1984\" concise-name=\"dwmlByDay\" operational-mode=\"official\"><title>NOAA's National Weather Service Forecast by 24 Hour Period</title><field>meteorological</field><category>forecast</category><creation-date refresh-frequency=\"PT1H\">2009-03-22T22:56:32Z</creation-date></product><source><more-information>http://www.nws.noaa.gov/forecasts/xml/</more-information><production-center>Meteorological Development Laboratory<sub-center>Product Generation Branch</sub-center></production-center><disclaimer>http://www.nws.noaa.gov/disclaimer.html</disclaimer><credit>http://www.weather.gov/</credit><credit-logo>http://www.weather.gov/images/xml_logo.gif</credit-logo><feedback>http://www.weather.gov/feedback.php</feedback></source></head><data><location><location-key>point1</location-key><point latitude=\"39.91\" longitude=\"-121.29\"/></location><moreWeatherInformation applicable-location=\"point1\">http://forecast.weather.gov/MapClick.php?textField1=39.91&textField2=-121.29</moreWeatherInformation><time-layout time-coordinate=\"local\" summarization=\"24hourly\"><layout-key>k-p24h-n4-1</layout-key><start-valid-time>2009-03-22T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-23T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-23T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-24T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-24T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-25T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-25T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-26T06:00:00-07:00</end-valid-time></time-layout><time-layout time-coordinate=\"local\" summarization=\"12hourly\"><layout-key>k-p12h-n8-2</layout-key><start-valid-time>2009-03-22T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-22T18:00:00-07:00</end-valid-time><start-valid-time>2009-03-22T18:00:00-07:00</start-valid-time><end-valid-time>2009-03-23T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-23T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-23T18:00:00-07:00</end-valid-time><start-valid-time>2009-03-23T18:00:00-07:00</start-valid-time><end-valid-time>2009-03-24T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-24T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-24T18:00:00-07:00</end-valid-time><start-valid-time>2009-03-24T18:00:00-07:00</start-valid-time><end-valid-time>2009-03-25T06:00:00-07:00</end-valid-time><start-valid-time>2009-03-25T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-25T18:00:00-07:00</end-valid-time><start-valid-time>2009-03-25T18:00:00-07:00</start-valid-time><end-valid-time>2009-03-26T06:00:00-07:00</end-valid-time></time-layout><time-layout time-coordinate=\"local\" summarization=\"24hourly\"><layout-key>k-p4d-n1-3</layout-key><start-valid-time>2009-03-22T06:00:00-07:00</start-valid-time><end-valid-time>2009-03-26T06:00:00-07:00</end-valid-time></time-layout><parameters applicable-location=\"point1\"><temperature type=\"maximum\" units=\"Fahrenheit\" time-layout=\"k-p24h-n4-1\"><name>Daily Maximum Temperature</name><value>32</value><value>47</value><value>55</value><value>58</value></temperature><temperature type=\"minimum\" units=\"Fahrenheit\" time-layout=\"k-p24h-n4-1\"><name>Daily Minimum Temperature</name><value>24</value><value>28</value><value>32</value><value>31</value></temperature><probability-of-precipitation type=\"12 hour\" units=\"percent\" time-layout=\"k-p12h-n8-2\"><name>12 Hourly Probability of Precipitation</name><value>98</value><value>22</value><value>6</value><value>6</value><value>4</value><value>0</value><value>16</value><value>18</value></probability-of-precipitation><weather time-layout=\"k-p24h-n4-1\"><name>Weather Type, Coverage, and Intensity</name><weather-conditions weather-summary=\"Slight Chance Snow Showers\"><value coverage=\"slight chance\" intensity=\"light\" weather-type=\"snow showers\" qualifier=\"none\"/></weather-conditions><weather-conditions weather-summary=\"Partly Cloudy\"/><weather-conditions weather-summary=\"Mostly Sunny\"/><weather-conditions weather-summary=\"Partly Cloudy\"/></weather><conditions-icon type=\"forecast-NWS\" time-layout=\"k-p24h-n4-1\"><name>Conditions Icons</name><icon-link>http://www.nws.noaa.gov/weather/images/fcicons/sn100.jpg</icon-link><icon-link>http://www.nws.noaa.gov/weather/images/fcicons/sct.jpg</icon-link><icon-link>http://www.nws.noaa.gov/weather/images/fcicons/few.jpg</icon-link><icon-link>http://www.nws.noaa.gov/weather/images/fcicons/sct.jpg</icon-link></conditions-icon><hazards time-layout=\"k-p4d-n1-3\"><name>Watches, Warnings, and Advisories</name><hazard-conditions><hazard hazardCode=\"LW.Y\" phenomena=\"Lake Wind\" significance=\"Advisory\" hazardType=\"long duration\"><hazardTextURL>http://forecast.weather.gov/wwamap/wwatxtget.php?cwa=usa&wwa=Lake%20Wind%20Advisory</hazardTextURL></hazard></hazard-conditions></hazards></parameters></data></dwml>"; 110 111 /** 112 * Recycled string builder used by {@link #parseDate(String)}. 113 */ 114 private static Editable sEditable = new SpannableStringBuilder(); 115 116 /** 117 * Recycled timestamp used by {@link #parseDate(String)}. 118 */ 119 private static Time sTime = new Time(); 120 121 /** 122 * Exception to inform callers that we ran into problems while parsing the 123 * forecast returned by the webservice. 124 */ 125 public static final class ForecastParseException extends Exception { 126 public ForecastParseException(String detailMessage) { 127 super(detailMessage); 128 } 129 130 public ForecastParseException(String detailMessage, Throwable throwable) { 131 super(detailMessage, throwable); 132 } 133 } 134 135 /** 136 * Parse a NWS date string into a Unix timestamp. Assumes incoming values 137 * are in the format "2009-03-23T18:00:00-07:00", which we adjust slightly 138 * to correctly follow RFC 3339 before parsing. 139 */ 140 private static long parseDate(String raw) throws TimeFormatException { 141 // Inject milliseconds so that NWS dates follow RFC 142 sEditable.clear(); 143 sEditable.append(raw); 144 sEditable.insert(19, ".000"); 145 146 String rfcFormat = sEditable.toString(); 147 sTime.parse3339(rfcFormat); 148 return sTime.toMillis(false); 149 } 150 151 /** 152 * Class holding a specific forecast at a point in time. 153 */ 154 private static class Forecast { 155 boolean alert = false; 156 long validStart = Long.MIN_VALUE; 157 int tempHigh = Integer.MIN_VALUE; 158 int tempLow = Integer.MIN_VALUE; 159 String conditions; 160 String url; 161 } 162 163 /** 164 * Retrieve a specific {@link Forecast} object from the given {@link Map} 165 * structure. If the {@link Forecast} doesn't exist, it's created and 166 * returned. 167 */ 168 private static Forecast getForecast(Map<String, List<Forecast>> forecasts, 169 String layout, int index) { 170 if (!forecasts.containsKey(layout)) { 171 forecasts.put(layout, new ArrayList<Forecast>()); 172 } 173 List<Forecast> layoutSpecific = forecasts.get(layout); 174 175 while (index >= layoutSpecific.size()) { 176 layoutSpecific.add(new Forecast()); 177 } 178 return layoutSpecific.get(index); 179 } 180 181 /** 182 * Flatten a set of {@link Forecast} objects that are separated into 183 * <code>time-layout</code> sections in the given {@link Map}. This discards 184 * any forecasts that have empty {@link Forecast#conditions}. 185 * <p> 186 * Sorts the resulting list by time, with any alerts forced to the top. 187 */ 188 private static List<Forecast> flattenForecasts(Map<String, List<Forecast>> forecasts) { 189 List<Forecast> flat = new ArrayList<Forecast>(); 190 191 // Collect together all forecasts that have valid conditions 192 for (String layout : forecasts.keySet()) { 193 for (Forecast forecast : forecasts.get(layout)) { 194 if (!TextUtils.isEmpty(forecast.conditions)) { 195 flat.add(forecast); 196 } 197 } 198 } 199 200 // Sort by time, but always bump alerts to top 201 Collections.sort(flat, new Comparator<Forecast>() { 202 public int compare(Forecast left, Forecast right) { 203 if (left.alert) { 204 return -1; 205 } else { 206 return (int)(left.validStart - right.validStart); 207 } 208 } 209 }); 210 211 return flat; 212 } 213 214 /** 215 * Perform a webservice query to retrieve and store the forecast for the 216 * given widget. This call blocks until request is finished and 217 * {@link Forecasts#CONTENT_URI} has been updated. 218 */ 219 public static void updateForecasts(Context context, Uri appWidgetUri, int days) 220 throws ForecastParseException { 221 222 Uri appWidgetForecasts = Uri.withAppendedPath(appWidgetUri, AppWidgets.TWIG_FORECASTS); 223 224 ContentResolver resolver = context.getContentResolver(); 225 226 Cursor cursor = null; 227 double lat = Double.NaN; 228 double lon = Double.NaN; 229 230 // Pull exact forecast location from database 231 try { 232 cursor = resolver.query(appWidgetUri, PROJECTION_APPWIDGET, null, null, null); 233 if (cursor != null && cursor.moveToFirst()) { 234 lat = cursor.getDouble(COL_LAT); 235 lon = cursor.getDouble(COL_LON); 236 } 237 } finally { 238 if (cursor != null) { 239 cursor.close(); 240 } 241 } 242 243 // Query webservice for this location 244 List<Forecast> forecasts = queryLocation(lat, lon, days); 245 246 if (forecasts == null || forecasts.size() == 0) { 247 throw new ForecastParseException("No forecasts found from webservice query"); 248 } 249 250 // Purge existing forecasts covered by incoming data, and anything 251 // before today 252 long lastMidnight = ForecastUtils.getLastMidnight(); 253 long earliest = Long.MAX_VALUE; 254 for (Forecast forecast : forecasts) { 255 earliest = Math.min(earliest, forecast.validStart); 256 } 257 258 resolver.delete(appWidgetForecasts, 259 ForecastsColumns.VALID_START + " >= " + earliest + " OR " + 260 ForecastsColumns.VALID_START + " <= " + lastMidnight, null); 261 262 // Insert any new forecasts found 263 ContentValues values = new ContentValues(); 264 for (Forecast forecast : forecasts) { 265 Log.d(TAG, "inserting forecast with validStart=" + forecast.validStart); 266 values.clear(); 267 values.put(ForecastsColumns.VALID_START, forecast.validStart); 268 values.put(ForecastsColumns.TEMP_HIGH, forecast.tempHigh); 269 values.put(ForecastsColumns.TEMP_LOW, forecast.tempLow); 270 values.put(ForecastsColumns.CONDITIONS, forecast.conditions); 271 values.put(ForecastsColumns.URL, forecast.url); 272 if (forecast.alert) { 273 values.put(ForecastsColumns.ALERT, ForecastsColumns.ALERT_TRUE); 274 } 275 resolver.insert(appWidgetForecasts, values); 276 } 277 278 // Mark widget cache as being updated 279 values.clear(); 280 values.put(AppWidgetsColumns.LAST_UPDATED, System.currentTimeMillis()); 281 resolver.update(appWidgetUri, values, null, null); 282 } 283 284 /** 285 * Query the given location and parse any returned data into a set of 286 * {@link Forecast} objects. This is a blocking call while waiting for the 287 * webservice to return. 288 */ 289 private static List<Forecast> queryLocation(double lat, double lon, int days) 290 throws ForecastParseException { 291 292 if (Double.isNaN(lat) || Double.isNaN(lon)) { 293 throw new ForecastParseException("Requested forecast for invalid location"); 294 } else { 295 Log.d(TAG, String.format("queryLocation() with lat=%f, lon=%f, days=%d", lat, lon, days)); 296 } 297 298 Reader responseReader; 299 List<Forecast> forecasts = null; 300 301 if (FAKE_DATA) { 302 // Feed back fake data, if requested 303 responseReader = new StringReader(EXAMPLE_RESPONSE); 304 305 } else { 306 // Perform webservice query and parse result 307 HttpClient client = new DefaultHttpClient(); 308 HttpGet request = new HttpGet(String.format(WEBSERVICE_URL, lat, lon, days)); 309 310 try { 311 HttpResponse response = client.execute(request); 312 313 StatusLine status = response.getStatusLine(); 314 Log.d(TAG, "Request returned status " + status); 315 316 HttpEntity entity = response.getEntity(); 317 responseReader = new InputStreamReader(entity.getContent()); 318 319 } catch (IOException e) { 320 throw new ForecastParseException("Problem calling forecast API", e); 321 } 322 } 323 324 // If response found, send through to parser 325 if (responseReader != null) { 326 forecasts = parseResponse(responseReader); 327 } 328 329 return forecasts; 330 } 331 332 /** 333 * Parse a webservice XML response into {@link Forecast} objects. 334 */ 335 private static List<Forecast> parseResponse(Reader response) 336 throws ForecastParseException { 337 // Keep a temporary mapping between time series tags and forecasts 338 Map<String, List<Forecast>> forecasts = new HashMap<String, List<Forecast>>(); 339 String detailsUrl = null; 340 341 try { 342 XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); 343 XmlPullParser xpp = factory.newPullParser(); 344 345 int index = 0; 346 String thisTag = null; 347 String thisLayout = null; 348 String thisType = null; 349 350 xpp.setInput(response); 351 int eventType = xpp.getEventType(); 352 while (eventType != XmlPullParser.END_DOCUMENT) { 353 if (eventType == XmlPullParser.START_TAG) { 354 thisTag = xpp.getName(); 355 356 if (TAG_TEMPERATURE.equals(thisTag) || TAG_WEATHER.equals(thisTag) 357 || TAG_POP.equals(thisTag) || TAG_HAZARDS.equals(thisTag)) { 358 thisLayout = xpp.getAttributeValue(null, ATTR_TIME_LAYOUT); 359 thisType = xpp.getAttributeValue(null, ATTR_TYPE); 360 index = -1; 361 362 } else if (TAG_WEATHER_CONDITIONS.equals(thisTag)) { 363 Forecast forecast = getForecast(forecasts, thisLayout, ++index); 364 forecast.conditions = xpp.getAttributeValue(null, ATTR_WEATHER_SUMMARY); 365 366 } else if (TAG_HAZARD.equals(thisTag)) { 367 Forecast forecast = getForecast(forecasts, thisLayout, ++index); 368 forecast.alert = true; 369 forecast.conditions = xpp.getAttributeValue(null, ATTR_PHENOMENA) + " " 370 + xpp.getAttributeValue(null, ATTR_SIGNIFICANCE); 371 } 372 373 } else if (eventType == XmlPullParser.END_TAG) { 374 thisTag = null; 375 376 } else if (eventType == XmlPullParser.TEXT) { 377 if (TAG_LAYOUT_KEY.equals(thisTag)) { 378 thisLayout = xpp.getText(); 379 index = -1; 380 381 } else if (TAG_START_VALID_TIME.equals(thisTag)) { 382 Forecast forecast = getForecast(forecasts, thisLayout, ++index); 383 forecast.validStart = parseDate(xpp.getText()); 384 385 } else if (TAG_VALUE.equals(thisTag) && TYPE_MAXIMUM.equals(thisType)) { 386 Forecast forecast = getForecast(forecasts, thisLayout, ++index); 387 forecast.tempHigh = Integer.parseInt(xpp.getText()); 388 forecast.url = detailsUrl; 389 390 } else if (TAG_VALUE.equals(thisTag) && TYPE_MINIMUM.equals(thisType)) { 391 Forecast forecast = getForecast(forecasts, thisLayout, ++index); 392 forecast.tempLow = Integer.parseInt(xpp.getText()); 393 394 } else if (TAG_HAZARDTEXTURL.equals(thisTag)) { 395 Forecast forecast = getForecast(forecasts, thisLayout, index); 396 forecast.url = xpp.getText(); 397 398 } else if (TAG_MOREWEATHERINFORMATION.equals(thisTag)) { 399 detailsUrl = xpp.getText(); 400 401 } 402 } 403 eventType = xpp.next(); 404 } 405 } catch (IOException e) { 406 throw new ForecastParseException("Problem parsing XML forecast", e); 407 } catch (XmlPullParserException e) { 408 throw new ForecastParseException("Problem parsing XML forecast", e); 409 } catch (TimeFormatException e) { 410 throw new ForecastParseException("Problem parsing XML forecast", e); 411 } 412 413 // Flatten non-empty forecasts into single list 414 return flattenForecasts(forecasts); 415 } 416}