Java tutorial
/* * Copyright 2013 2015 Ricki Hirner (bitfire web engineering). * All rights reserved. This program and the accompanying materials * are made available under the terms of the GNU Public License v3.0 * which accompanies this distribution, and is available at * http://www.gnu.org/licenses/gpl.html */ package at.bitfire.davdroid; import android.util.Log; import net.fortuna.ical4j.model.Date; import net.fortuna.ical4j.model.DateList; import net.fortuna.ical4j.model.DateTime; import net.fortuna.ical4j.model.TimeZone; import net.fortuna.ical4j.model.TimeZoneRegistry; import net.fortuna.ical4j.model.TimeZoneRegistryFactory; import net.fortuna.ical4j.model.parameter.Value; import net.fortuna.ical4j.model.property.DateListProperty; import org.apache.commons.lang3.StringUtils; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.LinkedList; import java.util.List; import java.util.SimpleTimeZone; public class DateUtils { private final static String TAG = "davdroid.DateUtils"; public static final TimeZoneRegistry tzRegistry = TimeZoneRegistryFactory.getInstance().createRegistry(); static { // disable automatic time-zone updates (causes unwanted network traffic) System.setProperty("net.fortuna.ical4j.timezone.update.enabled", "false"); } // time zones public static String findAndroidTimezoneID(String tz) { String deviceTZ = null; String availableTZs[] = SimpleTimeZone.getAvailableIDs(); // first, try to find an exact match (case insensitive) for (String availableTZ : availableTZs) if (availableTZ.equalsIgnoreCase(tz)) { deviceTZ = availableTZ; break; } // if that doesn't work, try to find something else that matches if (deviceTZ == null) { Log.w(TAG, "Coulnd't find time zone with matching identifiers, trying to guess"); for (String availableTZ : availableTZs) if (StringUtils.indexOfIgnoreCase(tz, availableTZ) != -1) { deviceTZ = availableTZ; break; } } // if that doesn't work, use UTC as fallback if (deviceTZ == null) { final String defaultTZ = TimeZone.getDefault().getID(); Log.e(TAG, "Couldn't identify time zone, using system default (" + defaultTZ + ") as fallback"); deviceTZ = defaultTZ; } return deviceTZ; } // recurrence sets /** * Concatenates, if necessary, multiple RDATE/EXDATE lists and converts them to * a formatted string which Android calendar provider can process. * Android expects this format: "[TZID;]date1,date2,date3" where date is "yyyymmddThhmmss" (when * TZID is given) or "yyyymmddThhmmssZ". We don't use the TZID format here because then we're limited * to one time-zone, while an iCalendar may contain multiple EXDATE/RDATE lines with different time zones. * @param dates one more more lists of RDATE or EXDATE * @param allDay indicates whether the event is an all-day event or not * @return formatted string for Android calendar provider: * - in case of all-day events, all dates/times are returned as yyyymmddT000000Z * - in case of timed events, all dates/times are returned as UTC time: yyyymmddThhmmssZ */ public static String recurrenceSetsToAndroidString(List<? extends DateListProperty> dates, boolean allDay) throws ParseException { List<String> strDates = new LinkedList<>(); /* rdate/exdate: DATE DATE_TIME all-day store as ...T000000Z cut off time and store as ...T000000Z event with time (ignored) store as ...ThhmmssZ */ final DateFormat dateFormatUtcMidnight = new SimpleDateFormat("yyyyMMdd'T'000000'Z'"); for (DateListProperty dateListProp : dates) { final Value type = dateListProp.getDates().getType(); if (Value.DATE_TIME.equals(type)) { // DATE-TIME values will be stored in UTC format for Android if (allDay) { DateList dateList = dateListProp.getDates(); for (Date date : dateList) strDates.add(dateFormatUtcMidnight.format(date)); } else { dateListProp.setUtc(true); strDates.add(dateListProp.getValue()); } } else if (Value.DATE.equals(type)) // DATE values have to be converted to DATE-TIME <date>T000000Z for Android for (Date date : dateListProp.getDates()) strDates.add(dateFormatUtcMidnight.format(date)); } return StringUtils.join(strDates, ","); } /** * Takes a formatted string as provided by the Android calendar provider and returns a DateListProperty * constructed from these values. * @param dbStr formatted string from Android calendar provider (RDATE/EXDATE field) * expected format: "[TZID;]date1,date2,date3" where date is "yyyymmddThhmmss[Z]" * @param type subclass of DateListProperty, e.g. RDate or ExDate * @param allDay true: list will contain DATE values; false: list will contain DATE_TIME values * @return instance of "type" containing the parsed dates/times from the string */ public static DateListProperty androidStringToRecurrenceSet(String dbStr, Class<? extends DateListProperty> type, boolean allDay) throws ParseException { // 1. split string into time zone and actual dates TimeZone timeZone; String datesStr; final int limiter = dbStr.indexOf(';'); if (limiter != -1) { // TZID given timeZone = DateUtils.tzRegistry.getTimeZone(dbStr.substring(0, limiter)); datesStr = dbStr.substring(limiter + 1); } else { timeZone = null; datesStr = dbStr; } // 2. process date string and generate list of DATEs or DATE-TIMEs DateList dateList; if (allDay) { dateList = new DateList(Value.DATE); for (String s : StringUtils.split(datesStr, ',')) dateList.add(new Date(new DateTime(s))); } else { dateList = new DateList(datesStr, Value.DATE_TIME, timeZone); if (timeZone == null) dateList.setUtc(true); } // 3. generate requested DateListProperty (RDate/ExDate) from list of DATEs or DATE-TIMEs DateListProperty list; try { list = (DateListProperty) type.getDeclaredConstructor(new Class[] { DateList.class }) .newInstance(dateList); if (dateList.getTimeZone() != null) list.setTimeZone(dateList.getTimeZone()); } catch (Exception e) { throw new ParseException("Couldn't create date/time list by reflection", -1); } return list; } }