/*
* Copyright 2002-2010 the original author or authors.
*
* 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 org.springframework.scheduling.support;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Calendar;
import java.util.Collections;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.TimeZone;
import org.springframework.util.StringUtils;
/**
* Date sequence generator for a <a href="http://www.manpagez.com/man/5/crontab/">Crontab pattern</a>,
* allowing clients to specify a pattern that the sequence matches.
*
* <p>The pattern is a list of six single space-separated fields: representing
* second, minute, hour, day, month, weekday. Month and weekday names can be
* given as the first three letters of the English names.
*
* <p>Example patterns:
* <ul>
* <li>"0 0 * * * *" = the top of every hour of every day.</li>
* <li>"*/10 * * * * *" = every ten seconds.</li>
* <li>"0 0 8-10 * * *" = 8, 9 and 10 o'clock of every day.</li>
* <li>"0 0/30 8-10 * * *" = 8:00, 8:30, 9:00, 9:30 and 10 o'clock every day.</li>
* <li>"0 0 9-17 * * MON-FRI" = on the hour nine-to-five weekdays</li>
* <li>"0 0 0 25 12 ?" = every Christmas Day at midnight</li>
* </ul>
*
* @author Dave Syer
* @author Juergen Hoeller
* @since 3.0
* @see CronTrigger
*/
public class CronSequenceGenerator {
private final BitSet seconds = new BitSet(60);
private final BitSet minutes = new BitSet(60);
private final BitSet hours = new BitSet(24);
private final BitSet daysOfWeek = new BitSet(7);
private final BitSet daysOfMonth = new BitSet(31);
private final BitSet months = new BitSet(12);
private final String expression;
private final TimeZone timeZone;
/**
* Construct a {@link CronSequenceGenerator} from the pattern provided.
* @param expression a space-separated list of time fields
* @param timeZone the TimeZone to use for generated trigger times
* @throws IllegalArgumentException if the pattern cannot be parsed
*/
public CronSequenceGenerator(String expression, TimeZone timeZone) {
this.expression = expression;
this.timeZone = timeZone;
parse(expression);
}
/**
* Get the next {@link Date} in the sequence matching the Cron pattern and
* after the value provided. The return value will have a whole number of
* seconds, and will be after the input value.
* @param date a seed value
* @return the next value matching the pattern
*/
public Date next(Date date) {
/*
The plan:
1 Round up to the next whole second
2 If seconds match move on, otherwise find the next match:
2.1 If next match is in the next minute then roll forwards
3 If minute matches move on, otherwise find the next match
3.1 If next match is in the next hour then roll forwards
3.2 Reset the seconds and go to 2
4 If hour matches move on, otherwise find the next match
4.1 If next match is in the next day then roll forwards,
4.2 Reset the minutes and seconds and go to 2
...
*/
Calendar calendar = new GregorianCalendar();
calendar.setTimeZone(this.timeZone);
calendar.setTime(date);
// Truncate to the next whole second
calendar.add(Calendar.SECOND, 1);
calendar.set(Calendar.MILLISECOND, 0);
doNext(calendar, calendar.get(Calendar.YEAR));
return calendar.getTime();
}
private void doNext(Calendar calendar, int dot) {
List<Integer> resets = new ArrayList<Integer>();
int second = calendar.get(Calendar.SECOND);
List<Integer> emptyList = Collections.emptyList();
int updateSecond = findNext(this.seconds, second, calendar, Calendar.SECOND, Calendar.MINUTE, emptyList);
if (second == updateSecond) {
resets.add(Calendar.SECOND);
}
int minute = calendar.get(Calendar.MINUTE);
int updateMinute = findNext(this.minutes, minute, calendar, Calendar.MINUTE, Calendar.HOUR_OF_DAY, resets);
if (minute == updateMinute) {
resets.add(Calendar.MINUTE);
} else {
doNext(calendar, dot);
}
int hour = calendar.get(Calendar.HOUR_OF_DAY);
int updateHour = findNext(this.hours, hour, calendar, Calendar.HOUR_OF_DAY, Calendar.DAY_OF_WEEK, resets);
if (hour == updateHour) {
resets.add(Calendar.HOUR_OF_DAY);
} else {
doNext(calendar, dot);
}
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
int updateDayOfMonth = findNextDay(calendar, this.daysOfMonth, dayOfMonth, daysOfWeek, dayOfWeek, resets);
if (dayOfMonth == updateDayOfMonth) {
resets.add(Calendar.DAY_OF_MONTH);
} else {
doNext(calendar, dot);
}
int month = calendar.get(Calendar.MONTH);
int updateMonth = findNext(this.months, month, calendar, Calendar.MONTH, Calendar.YEAR, resets);
if (month != updateMonth) {
if (calendar.get(Calendar.YEAR) - dot > 4) {
throw new IllegalStateException("Invalid cron expression led to runaway search for next trigger");
}
doNext(calendar, dot);
}
}
private int findNextDay(Calendar calendar, BitSet daysOfMonth, int dayOfMonth, BitSet daysOfWeek, int dayOfWeek,
List<Integer> resets) {
int count = 0;
int max = 366;
// the DAY_OF_WEEK values in java.util.Calendar start with 1 (Sunday),
// but in the cron pattern, they start with 0, so we subtract 1 here
while ((!daysOfMonth.get(dayOfMonth) || !daysOfWeek.get(dayOfWeek - 1)) && count++ < max) {
calendar.add(Calendar.DAY_OF_MONTH, 1);
dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
reset(calendar, resets);
}
if (count >= max) {
throw new IllegalStateException("Overflow in day for expression=" + this.expression);
}
return dayOfMonth;
}
/**
* Search the bits provided for the next set bit after the value provided,
* and reset the calendar.
* @param bits a {@link BitSet} representing the allowed values of the field
* @param value the current value of the field
* @param calendar the calendar to increment as we move through the bits
* @param field the field to increment in the calendar (@see
* {@link Calendar} for the static constants defining valid fields)
* @param lowerOrders the Calendar field ids that should be reset (i.e. the
* ones of lower significance than the field of interest)
* @return the value of the calendar field that is next in the sequence
*/
private int findNext(BitSet bits, int value, Calendar calendar, int field, int nextField, List<Integer> lowerOrders) {
int nextValue = bits.nextSetBit(value);
// roll over if needed
if (nextValue == -1) {
calendar.add(nextField, 1);
reset(calendar, Arrays.asList(field));
nextValue = bits.nextSetBit(0);
}
if (nextValue != value) {
calendar.set(field, nextValue);
reset(calendar, lowerOrders);
}
return nextValue;
}
/**
* Reset the calendar setting all the fields provided to zero.
*/
private void reset(Calendar calendar, List<Integer> fields) {
for (int field : fields) {
calendar.set(field, field == Calendar.DAY_OF_MONTH ? 1 : 0);
}
}
// Parsing logic invoked by the constructor.
/**
* Parse the given pattern expression.
*/
private void parse(String expression) throws IllegalArgumentException {
String[] fields = StringUtils.tokenizeToStringArray(expression, " ");
if (fields.length != 6) {
throw new IllegalArgumentException(String.format(""
+ "cron expression must consist of 6 fields (found %d in %s)", fields.length, expression));
}
setNumberHits(this.seconds, fields[0], 0, 60);
setNumberHits(this.minutes, fields[1], 0, 60);
setNumberHits(this.hours, fields[2], 0, 24);
setDaysOfMonth(this.daysOfMonth, fields[3]);
setMonths(this.months, fields[4]);
setDays(this.daysOfWeek, replaceOrdinals(fields[5], "SUN,MON,TUE,WED,THU,FRI,SAT"), 8);
if (this.daysOfWeek.get(7)) {
// Sunday can be represented as 0 or 7
this.daysOfWeek.set(0);
this.daysOfWeek.clear(7);
}
}
/**
* Replace the values in the commaSeparatedList (case insensitive) with
* their index in the list.
* @return a new string with the values from the list replaced
*/
private String replaceOrdinals(String value, String commaSeparatedList) {
String[] list = StringUtils.commaDelimitedListToStringArray(commaSeparatedList);
for (int i = 0; i < list.length; i++) {
String item = list[i].toUpperCase();
value = StringUtils.replace(value.toUpperCase(), item, "" + i);
}
return value;
}
private void setDaysOfMonth(BitSet bits, String field) {
int max = 31;
// Days of month start with 1 (in Cron and Calendar) so add one
setDays(bits, field, max + 1);
// ... and remove it from the front
bits.clear(0);
}
private void setDays(BitSet bits, String field, int max) {
if (field.contains("?")) {
field = "*";
}
setNumberHits(bits, field, 0, max);
}
private void setMonths(BitSet bits, String value) {
int max = 12;
value = replaceOrdinals(value, "FOO,JAN,FEB,MAR,APR,MAY,JUN,JUL,AUG,SEP,OCT,NOV,DEC");
BitSet months = new BitSet(13);
// Months start with 1 in Cron and 0 in Calendar, so push the values first into a longer bit set
setNumberHits(months, value, 1, max + 1);
// ... and then rotate it to the front of the months
for (int i = 1; i <= max; i++) {
if (months.get(i)) {
bits.set(i - 1);
}
}
}
private void setNumberHits(BitSet bits, String value, int min, int max) {
String[] fields = StringUtils.delimitedListToStringArray(value, ",");
for (String field : fields) {
if (!field.contains("/")) {
// Not an incrementer so it must be a range (possibly empty)
int[] range = getRange(field, min, max);
bits.set(range[0], range[1] + 1);
} else {
String[] split = StringUtils.delimitedListToStringArray(field, "/");
if (split.length > 2) {
throw new IllegalArgumentException("Incrementer has more than two fields: " + field);
}
int[] range = getRange(split[0], min, max);
if (!split[0].contains("-")) {
range[1] = max - 1;
}
int delta = Integer.valueOf(split[1]);
for (int i = range[0]; i <= range[1]; i += delta) {
bits.set(i);
}
}
}
}
private int[] getRange(String field, int min, int max) {
int[] result = new int[2];
if (field.contains("*")) {
result[0] = min;
result[1] = max - 1;
return result;
}
if (!field.contains("-")) {
result[0] = result[1] = Integer.valueOf(field);
} else {
String[] split = StringUtils.delimitedListToStringArray(field, "-");
if (split.length > 2) {
throw new IllegalArgumentException("Range has more than two fields: " + field);
}
result[0] = Integer.valueOf(split[0]);
result[1] = Integer.valueOf(split[1]);
}
if (result[0] >= max || result[1] >= max) {
throw new IllegalArgumentException("Range exceeds maximum (" + max + "): " + field);
}
if (result[0] < min || result[1] < min) {
throw new IllegalArgumentException("Range less than minimum (" + min + "): " + field);
}
return result;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof CronSequenceGenerator)) {
return false;
}
CronSequenceGenerator cron = (CronSequenceGenerator) obj;
return cron.months.equals(this.months) && cron.daysOfMonth.equals(this.daysOfMonth)
&& cron.daysOfWeek.equals(this.daysOfWeek) && cron.hours.equals(this.hours)
&& cron.minutes.equals(this.minutes) && cron.seconds.equals(this.seconds);
}
@Override
public int hashCode() {
return 37 + 17 * this.months.hashCode() + 29 * this.daysOfMonth.hashCode() + 37 * this.daysOfWeek.hashCode()
+ 41 * this.hours.hashCode() + 53 * this.minutes.hashCode() + 61 * this.seconds.hashCode();
}
@Override
public String toString() {
return getClass().getSimpleName() + ": " + this.expression;
}
}
|