http://www.quartz-scheduler.org/documentation/quartz-2.x/tutorials/crontrigger.html
task:scheduled
org.springframework.scheduling.support.CronSequenceGenerator.parse
/** * 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); } }
cron="* * * * * *"
1. 只能有6个域
2. 域之间通过空格拆分
3. 六个域分别是：
- seconds 0-59
- minutes 0-59
- hours 0-23
- daysOfMonth 1-31
- months 1-12 or JAN-DEC
- daysOfWeek 0-7 or SUN-SAT
4. daysOfWeek 由固定顺序的[SUN,MON,TUE,WED,THU,FRI,SAT] 替换域中出现的星期
5. daysOfWeek 用英文缩写时不区分大小写
6. daysOfWeek 用数字时，0 和 7 都代表星期日。7最终会被0代替。
7. daysOfWeek 和 daysOfMonth 中可以使用 【?】 但最终会被 【*】 代替
8. range 可用 【-】 表示，前后必须是域的可用值
9. range 【-】和【? or *】联用，【-】会被忽略
10. 【,】可以连接多个子域，为并集关系，但不存在重复值
11. 【/】是一个子域 ，比如 seconds 50/2 ，50会扩展为50-59，然后从中挑选50,52,54,56,58
12. 【/】 是一个子域，比如 seconds 50-58/4 or */4 扩展为0-59/4 or 20-*/4 扩展为0-59/4 ，有*出现则忽略其他
12. 多子域情况，daysOfMonth 1,2,15-17,20-31/2 代表：1, 2, 15, 16, 17, 20, 22, 24, 26, 28, 30
CronSequenceGenerator源码
/* * Copyright 2002-2013 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, * using the default {@link TimeZone}. * @param expression a space-separated list of time fields * @throws IllegalArgumentException if the pattern cannot be parsed * @see java.util.TimeZone#getDefault() */ public CronSequenceGenerator(String expression) { this(expression, TimeZone.getDefault()); } /** * Construct a {@link CronSequenceGenerator} from the pattern provided, * using the specified {@link TimeZone}. * @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); // First, just reset the milliseconds and try to calculate from there... calendar.set(Calendar.MILLISECOND, 0); long originalTimestamp = calendar.getTimeInMillis(); doNext(calendar, calendar.get(Calendar.YEAR)); if (calendar.getTimeInMillis() == originalTimestamp) { // We arrived at the original timestamp - round up to the next whole second and try again... calendar.add(Calendar.SECOND, 1); 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 IllegalArgumentException("Invalid cron expression \"" + this.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 IllegalArgumentException("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 + "' in expression \"" + this.expression + "\""); } 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 + "' in expression \"" + this.expression + "\""); } 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 + "' in expression \"" + this.expression + "\""); } if (result[0] < min || result[1] < min) { throw new IllegalArgumentException("Range less than minimum (" + min + "): '" + field + "' in expression \"" + this.expression + "\""); } return result; } String getExpression() { return this.expression; } @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; } }