Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.commons.lang; import java.text.*; import java.util.*; /** * A suite of utilities surrounding the use of the Calendar and Date object. * * @author <a href="mailto:sergek@lokitech.com">Serge Knystautas</a> */ public class CalendarUtils { /** * This is half a month, so this represents whether a date is in the top * or bottom half of the month. */ public final static int SEMI_MONTH = 1001; private static final int[][] fields = { { Calendar.MILLISECOND }, { Calendar.SECOND }, { Calendar.MINUTE }, { Calendar.HOUR_OF_DAY, Calendar.HOUR }, { Calendar.DATE, Calendar.DAY_OF_MONTH, Calendar.AM_PM /* Calendar.DAY_OF_YEAR, Calendar.DAY_OF_WEEK, Calendar.DAY_OF_WEEK_IN_MONTH */ }, { Calendar.MONTH, CalendarUtils.SEMI_MONTH }, { Calendar.YEAR }, { Calendar.ERA } }; private static DateFormat[] dateFormats = { //3/31/92 10:00:07 PST new SimpleDateFormat("M/dd/yy h:mm:ss z"), //January 23, 1987 10:05pm new SimpleDateFormat("MMM d, yyyy h:mm a"), //22:00 GMT new SimpleDateFormat("h:mm z") }; /** * A week range, starting on Sunday. */ public final static int RANGE_WEEK_SUNDAY = 1; /** * A week range, starting on Monday. */ public final static int RANGE_WEEK_MONDAY = 2; /** * A week range, starting on the day focused. */ public final static int RANGE_WEEK_RELATIVE = 3; /** * A week range, centered around the day focused. */ public final static int RANGE_WEEK_CENTER = 4; /** * A month range, the week starting on Sunday. */ public final static int RANGE_MONTH_SUNDAY = 5; /** * A month range, the week starting on Monday. */ public final static int RANGE_MONTH_MONDAY = 6; /** * See the other round method. Works with a Date object. */ public static Date round(Date val, int field) { GregorianCalendar gval = new GregorianCalendar(); gval.setTime(val); modify(gval, field, true); return gval.getTime(); } /** * Round this date, leaving the field specified as the most significant * field. For example, if you had the datetime of 28 Mar 2002 * 13:45:01.231, if this was passed with HOUR, it would return 28 Mar * 2002 14:00:00.000. If this was passed with MONTH, it would return * 1 April 2002 0:00:00.000. */ public static Calendar round(Calendar val, int field) { Calendar rounded = (Calendar) val.clone(); modify(rounded, field, true); return rounded; } /** * See the other round method. Works with an Object, trying to * use it as either a Date or Calendar. */ public static Date round(Object val, int field) { if (val instanceof Date) { return round((Date) val, field); } else if (val instanceof Calendar) { return round((Calendar) val, field).getTime(); } else { throw new ClassCastException("Could not round " + val); } } /** * See the other trunc method. Works with a Date. */ public static Date trunc(Date val, int field) { GregorianCalendar gval = new GregorianCalendar(); gval.setTime(val); modify(gval, field, false); return gval.getTime(); } /** * Truncate this date, leaving the field specified as the most significant * field. For example, if you had the datetime of 28 Mar 2002 * 13:45:01.231, if you passed with HOUR, it would return 28 Mar * 2002 13:00:00.000. If this was passed with MONTH, it would return * 1 Mar 2002 0:00:00.000. */ public static Calendar trunc(Calendar val, int field) { Calendar truncated = (Calendar) val.clone(); modify(truncated, field, false); return truncated; } /** * See the other trunc method. Works with an Object, trying to * use it as either a Date or Calendar. */ public static Date trunc(Object val, int field) { if (val instanceof Date) { return trunc((Date) val, field); } else if (val instanceof Calendar) { return trunc((Calendar) val, field).getTime(); } else { throw new ClassCastException("Could not trunc " + val); } } private static void modify(Calendar val, int field, boolean round) { boolean roundUp = false; for (int i = 0; i < fields.length; i++) { for (int j = 0; j < fields[i].length; j++) { if (fields[i][j] == field) { //This is our field... we stop looping if (round && roundUp) { if (field == CalendarUtils.SEMI_MONTH) { //This is a special case that's hard to generalize //If the date is 1, we round up to 16, otherwise // we subtract 15 days and add 1 month if (val.get(Calendar.DATE) == 1) { val.add(Calendar.DATE, 15); } else { val.add(Calendar.DATE, -15); val.add(Calendar.MONTH, 1); } } else { //We need at add one to this field since the // last number causes us to round up val.add(fields[i][0], 1); } } return; } } //We have various fields that are not easy roundings int offset = 0; boolean offsetSet = false; //These are special types of fields that require different rounding rules switch (field) { case CalendarUtils.SEMI_MONTH: if (fields[i][0] == Calendar.DATE) { //If we're going to drop the DATE field's value, // we want to do this our own way. //We need to subtrace 1 since the date has a minimum of 1 offset = val.get(Calendar.DATE) - 1; //If we're above 15 days adjustment, that means we're in the // bottom half of the month and should stay accordingly. if (offset >= 15) { offset -= 15; } //Record whether we're in the top or bottom half of that range roundUp = offset > 7; offsetSet = true; } break; case Calendar.AM_PM: if (fields[i][0] == Calendar.HOUR) { //If we're going to drop the HOUR field's value, // we want to do this our own way. offset = val.get(Calendar.HOUR); if (offset >= 12) { offset -= 12; } roundUp = offset > 6; offsetSet = true; } break; } if (!offsetSet) { int min = val.getActualMinimum(fields[i][0]); int max = val.getActualMaximum(fields[i][0]); //Calculate the offset from the minimum allowed value offset = val.get(fields[i][0]) - min; //Set roundUp if this is more than half way between the minimum and maximum roundUp = offset > ((max - min) / 2); } //We need to remove this field val.add(fields[i][0], -offset); } throw new RuntimeException("We do not support that field."); } /** * Parses strings the way that CVS supports it... very human readable */ public static Calendar parse(String original) { return parse(original, Locale.getDefault()); } /** * Parses strings the way that CVS supports it... very human readable */ public static Calendar parse(String original, Locale locale) { //Get the symbol names DateFormatSymbols symbols = new DateFormatSymbols(locale); //Prep the string to parse String value = original.toLowerCase().trim(); //Get the current date/time Calendar now = Calendar.getInstance(); if (value.endsWith(" ago")) { //If this was a date that was "ago" the current time... //Strip out the ' ago' part value = value.substring(0, value.length() - 4); //Split the value and unit int start = value.indexOf(" "); if (start < 0) { throw new RuntimeException("Could not find space in between value and unit"); } String unit = value.substring(start + 1); value = value.substring(0, start); //We support "a week", so we need to parse the value as "a" int val = 0; if (value.equals("a") || value.equals("an")) { val = 1; } else { val = Integer.parseInt(value); } //Determine the unit if (unit.equals("milliseconds") || unit.equals("millisecond")) { now.add(Calendar.MILLISECOND, -val); } else if (unit.equals("seconds") || unit.equals("second")) { now.add(Calendar.SECOND, -val); } else if (unit.equals("minutes") || unit.equals("minute")) { now.add(Calendar.MINUTE, -val); } else if (unit.equals("hours") || unit.equals("hour")) { now.add(Calendar.HOUR, -val); } else if (unit.equals("days") || unit.equals("day")) { now.add(Calendar.DATE, -val); } else if (unit.equals("weeks") || unit.equals("week")) { now.add(Calendar.DATE, -val * 7); } else if (unit.equals("fortnights") || unit.equals("fortnight")) { now.add(Calendar.DATE, -val * 14); } else if (unit.equals("months") || unit.equals("month")) { now.add(Calendar.MONTH, -val); } else if (unit.equals("years") || unit.equals("year")) { now.add(Calendar.YEAR, -val); } else { throw new RuntimeException("We do not understand that many units ago"); } return now; } else if (value.startsWith("last ")) { //If this was the last time a certain field was met //Strip out the 'last ' part value = value.substring(5); //Get the current date/time String[] strings = symbols.getWeekdays(); for (int i = 0; i < strings.length; i++) { if (value.equalsIgnoreCase(strings[i])) { //How many days after Sunday int daysAgo = now.get(Calendar.DAY_OF_WEEK) - i; if (daysAgo <= 0) { daysAgo += 7; } now.add(Calendar.DATE, -daysAgo); return now; } } strings = symbols.getMonths(); for (int i = 0; i < strings.length; i++) { if (value.equalsIgnoreCase(strings[i])) { //How many days after January int monthsAgo = now.get(Calendar.MONTH) - i; if (monthsAgo <= 0) { monthsAgo += 12; } now.add(Calendar.MONTH, -monthsAgo); return now; } } if (value.equals("week")) { now.add(Calendar.DATE, -7); return now; } } else if (value.equals("yesterday")) { now.add(Calendar.DATE, -1); return now; } else if (value.equals("tomorrow")) { now.add(Calendar.DATE, 1); return now; } //Try to parse the date a number of different ways for (int i = 0; i < dateFormats.length; i++) { try { Date datetime = dateFormats[i].parse(original); Calendar cal = Calendar.getInstance(); cal.setTime(datetime); return cal; } catch (ParseException pe) { //we ignore this and just keep trying } } throw new RuntimeException("Unable to parse '" + original + "'."); } /** * This constructs an Iterator that will start and stop over a date * range based on the focused date and the range style. For instance, * passing Thursday, July 4, 2002 and a RANGE_MONTH_SUNDAY will return * an Iterator that starts with Sunday, June 30, 2002 and ends with * Saturday, August 3, 2002. */ public static Iterator getCalendarIterator(Calendar focus, int rangeStyle) { Calendar start = null; Calendar end = null; int startCutoff = Calendar.SUNDAY; int endCutoff = Calendar.SATURDAY; switch (rangeStyle) { case RANGE_MONTH_SUNDAY: case RANGE_MONTH_MONDAY: //Set start to the first of the month start = trunc(focus, Calendar.MONTH); //Set end to the last of the month end = (Calendar) start.clone(); end.add(Calendar.MONTH, 1); end.add(Calendar.DATE, -1); //Loop start back to the previous sunday or monday if (rangeStyle == RANGE_MONTH_MONDAY) { startCutoff = Calendar.MONDAY; endCutoff = Calendar.SUNDAY; } break; case RANGE_WEEK_SUNDAY: case RANGE_WEEK_MONDAY: case RANGE_WEEK_RELATIVE: case RANGE_WEEK_CENTER: //Set start and end to the current date start = trunc(focus, Calendar.DATE); end = trunc(focus, Calendar.DATE); switch (rangeStyle) { case RANGE_WEEK_SUNDAY: //already set by default break; case RANGE_WEEK_MONDAY: startCutoff = Calendar.MONDAY; endCutoff = Calendar.SUNDAY; break; case RANGE_WEEK_RELATIVE: startCutoff = focus.get(Calendar.DAY_OF_WEEK); endCutoff = startCutoff - 1; break; case RANGE_WEEK_CENTER: startCutoff = focus.get(Calendar.DAY_OF_WEEK) - 3; endCutoff = focus.get(Calendar.DAY_OF_WEEK) + 3; break; } break; default: throw new RuntimeException("The range style " + rangeStyle + " is not valid."); } if (startCutoff < Calendar.SUNDAY) { startCutoff += 7; } if (endCutoff > Calendar.SATURDAY) { endCutoff -= 7; } while (start.get(Calendar.DAY_OF_WEEK) != startCutoff) { start.add(Calendar.DATE, -1); } while (end.get(Calendar.DAY_OF_WEEK) != endCutoff) { end.add(Calendar.DATE, 1); } final Calendar startFinal = start; final Calendar endFinal = end; Iterator it = new Iterator() { Calendar spot = null; { spot = startFinal; spot.add(Calendar.DATE, -1); } public boolean hasNext() { return spot.before(endFinal); } public Object next() { if (spot.equals(endFinal)) { throw new NoSuchElementException(); } spot.add(Calendar.DATE, 1); return spot.clone(); } public void remove() { throw new UnsupportedOperationException(); } }; return it; } /** * See the other getCalendarIterator. Works with a Date. */ public static Iterator getCalendarIterator(Date focus, int rangeStyle) { GregorianCalendar gval = new GregorianCalendar(); gval.setTime(focus); return getCalendarIterator(gval, rangeStyle); } /** * See the other getCalendarIterator. Works with an Object, trying * to use it as a Date or Calendar. */ public static Iterator getCalendarIterator(Object focus, int rangeStyle) { if (focus instanceof Date) { return getCalendarIterator((Date) focus, rangeStyle); } else if (focus instanceof Calendar) { return getCalendarIterator((Calendar) focus, rangeStyle); } else { throw new ClassCastException("Could not iterate based on " + focus); } } }