修复cron无法生成小月的最后一天的bug；

hutool-cron/src/main/java/cn/hutool/cron/pattern/matcher/DayOfMonthMatcher.java

@@ -11,14 +11,19 @@ import java.util.List;
  * @author Looly
  */
 public class DayOfMonthMatcher extends BoolArrayMatcher {
+	/**
+	 * 是否是查询最后一天，即“L”
+	 */
+	private final boolean isLast;
 
 	/**
 	 * 构造
 	 *
 	 * @param intValueList 匹配的日值
 	 */
-	public DayOfMonthMatcher(List<Integer> intValueList) {
+	public DayOfMonthMatcher(List<Integer> intValueList, boolean isLast) {
 		super(intValueList);
+		this.isLast = isLast;
 	}
 
 	/**
@@ -50,4 +55,9 @@ public class DayOfMonthMatcher extends BoolArrayMatcher {
 	private static boolean isLastDayOfMonth(int value, int month, boolean isLeapYear) {
 		return value == Month.getLastDay(month - 1, isLeapYear);
 	}
+
+	public boolean isLast() {
+		return isLast;
+	}
+
 }

hutool-cron/src/main/java/cn/hutool/cron/pattern/matcher/PatternMatcher.java

@@ -1,5 +1,7 @@
 package cn.hutool.cron.pattern.matcher;
 
+import cn.hutool.core.date.DateUtil;
+import cn.hutool.core.date.Month;
 import cn.hutool.cron.pattern.Part;
 
 import java.time.Year;
@@ -184,14 +186,23 @@ public class PatternMatcher {
 				// 周不参与计算
 				i--;
 				continue;
-			}
+			} else if (i == Part.DAY_OF_MONTH.ordinal()
+				&& matchers[i] instanceof DayOfMonthMatcher
+				&& ((DayOfMonthMatcher) matchers[i]).isLast()) {
+				int newMonth = newValues[Part.MONTH.ordinal()];
+				int newYear = newValues[Part.YEAR.ordinal()];
+				nextValue = Month.of(newMonth - 1).getLastDay(DateUtil.isLeapYear(newYear));
+			} else {
 				nextValue = matchers[i].nextAfter(values[i]);
+			}
 			if (nextValue > values[i]) {
 				// 此部分正常获取新值，结束循环，后续的部分置最小值
 				newValues[i] = nextValue;
 				i--;
 				break;
 			} else if (nextValue < values[i]) {
+				// 回退前保存最新值
+				newValues[i] = nextValue;
 				// 此部分下一个值获取到的值产生回退，回到上一个部分，继续获取新值
 				i++;
 				nextValue = -1;// 标记回退查找
@@ -208,8 +219,15 @@ public class PatternMatcher {
 					// 周不参与计算
 					i++;
 					continue;
-				}
+				} else if (i == Part.DAY_OF_MONTH.ordinal()
+					&& matchers[i] instanceof DayOfMonthMatcher
+					&& ((DayOfMonthMatcher) matchers[i]).isLast()) {
+					int newMonth = newValues[Part.MONTH.ordinal()];
+					int newYear = newValues[Part.YEAR.ordinal()];
+					nextValue = Month.of(newMonth - 1).getLastDay(DateUtil.isLeapYear(newYear));
+				} else {
 					nextValue = matchers[i].nextAfter(values[i] + 1);
+				}
 				if (nextValue > values[i]) {
 					newValues[i] = nextValue;
 					i--;
@@ -234,9 +252,17 @@ public class PatternMatcher {
 		Part part;
 		for (int i = 0; i <= toPart; i++) {
 			part = Part.of(i);
+			if (part == Part.DAY_OF_MONTH
+				&& get(part) instanceof DayOfMonthMatcher
+				&& ((DayOfMonthMatcher) get(part)).isLast()) {
+				int newMonth = values[Part.MONTH.ordinal()];
+				int newYear = values[Part.YEAR.ordinal()];
+				values[i] = Month.of(newMonth - 1).getLastDay(DateUtil.isLeapYear(newYear));
+			} else {
 				values[i] = getMin(part);
 			}
 		}
+	}
 
 	/**
 	 * 获取表达式部分的最小值

hutool-cron/src/main/java/cn/hutool/cron/pattern/parser/PartParser.java

@@ -32,6 +32,10 @@ import java.util.List;
 public class PartParser {
 
 	private final Part part;
+	/**
+	 * 是否是查询最后一天
+	 */
+	private boolean isLastDay;
 
 	/**
 	 * 创建解析器
@@ -69,6 +73,7 @@ public class PartParser {
 			return new AlwaysTrueMatcher();
 		}
 
+		isLastDay = false;
 		final List<Integer> values = parseArray(value);
 		if (values.isEmpty()) {
 			throw new CronException("Invalid part value: [{}]", value);
@@ -76,7 +81,7 @@ public class PartParser {
 
 		switch (this.part) {
 			case DAY_OF_MONTH:
-				return new DayOfMonthMatcher(values);
+				return new DayOfMonthMatcher(values, isLastDay);
 			case YEAR:
 				return new YearValueMatcher(values);
 			default:
@@ -265,6 +270,7 @@ public class PartParser {
 	 */
 	private int parseAlias(String name) throws CronException {
 		if ("L".equalsIgnoreCase(name)) {
+			isLastDay = true;
 			// L表示最大值
 			return part.getMax();
 		}

hutool-cron/src/test/java/cn/hutool/cron/pattern/CronPatternNextMatchTest.java

@@ -97,4 +97,135 @@ public class CronPatternNextMatchTest {
 		final Calendar calendar = pattern.nextMatchAfter(time.toCalendar());
 		Assert.assertEquals("2022-04-09 01:01:01", DateUtil.date(calendar).toString());
 	}
+
+	@Test
+	public void testLastDayOfMonthForEveryMonth1() {
+		DateTime date = DateUtil.parse("2023-01-08 07:44:16");
+		DateTime result = DateUtil.parse("2023-01-31 03:02:01");
+		// 匹配所有月，生成每个月的最后一天
+		CronPattern pattern = new CronPattern("1 2 3 L * ?");
+		for (int i = 0; i < 30; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一个月的最后一天
+			result = result.offset(DateField.DAY_OF_MONTH, 1);
+			int lastDayOfMonth = DateUtil.getLastDayOfMonth(result);
+			result.setField(DateField.DAY_OF_MONTH, lastDayOfMonth);
+		}
+	}
+
+	@Test
+	public void testLastDayOfMonthForEveryMonth2() {
+		DateTime date = DateUtil.parse("2023-03-08 07:44:16");
+		DateTime result = DateUtil.parse("2023-03-31 03:02:01");
+		// 匹配所有月，生成每个月的最后一天
+		CronPattern pattern = new CronPattern("1 2 3 L * ?");
+		for (int i = 0; i < 30; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一个月的最后一天
+			result = result.offset(DateField.DAY_OF_MONTH, 1);
+			int lastDayOfMonth = DateUtil.getLastDayOfMonth(result);
+			result.setField(DateField.DAY_OF_MONTH, lastDayOfMonth);
+		}
+	}
+
+	@Test
+	public void testLastDayOfMonthForEveryYear1() {
+		DateTime date = DateUtil.parse("2023-01-08 07:44:16");
+		DateTime result = DateUtil.parse("2023-02-28 03:02:01");
+		// 匹配每一年2月的最后一天
+		CronPattern pattern = new CronPattern("1 2 3 L 2 ?");
+		for (int i = 0; i < 10; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一年的最后一天
+			result = result.offset(DateField.YEAR, 1);
+			int lastDayOfMonth = DateUtil.getLastDayOfMonth(result);
+			result.setField(DateField.DAY_OF_MONTH, lastDayOfMonth);
+		}
+	}
+
+	@Test
+	public void testLastDayOfMonthForEveryYear2() {
+		DateTime date = DateUtil.parse("2022-03-08 07:44:16");
+		DateTime result = DateUtil.parse("2023-02-28 03:02:01");
+		// 匹配每一年2月的最后一天
+		CronPattern pattern = new CronPattern("1 2 3 L 2 ?");
+		for (int i = 0; i < 30; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一年的最后一天
+			result = result.offset(DateField.YEAR, 1);
+			int lastDayOfMonth = DateUtil.getLastDayOfMonth(result);
+			result.setField(DateField.DAY_OF_MONTH, lastDayOfMonth);
+		}
+	}
+
+	@Test
+	public void testEveryHour() {
+		DateTime date = DateUtil.parse("2022-02-28 07:44:16");
+		DateTime result = DateUtil.parse("2022-02-28 08:02:01");
+		// 匹配每一年2月的最后一天
+		CronPattern pattern = new CronPattern("1 2 */1 * * ?");
+		for (int i = 0; i < 30; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一个小时
+			result = result.offset(DateField.HOUR_OF_DAY, 1);
+		}
+	}
+
+	@Test
+	public void testLastDayOfMonthForEveryHour() {
+		DateTime date = DateUtil.parse("2023-01-28 07:44:16");
+		DateTime result = DateUtil.parse("2023-01-31 00:00:00");
+		// 匹配每一年2月的最后一天
+		CronPattern pattern = new CronPattern("0 0 */1 L * ?");
+		for (int i = 0; i < 400; i++) {
+			//noinspection ConstantConditions
+			Calendar calendar = pattern.nextMatchAfter(date.toCalendar());
+			date = DateUtil.date(calendar);
+			Assert.assertEquals(date, result);
+			// 加一秒
+			date = date.offset(DateField.SECOND, 1);
+
+			// 移动到下一个小时
+			DateTime t = result.setMutable(false).offset(DateField.HOUR_OF_DAY, 1);
+			if (t.dayOfMonth() != result.dayOfMonth()) {
+				// 移动到下个月最后一天的开始
+				result = result.offset(DateField.DAY_OF_MONTH, 1);
+				int lastDayOfMonth = DateUtil.getLastDayOfMonth(result);
+				result = result.setField(DateField.DAY_OF_MONTH, lastDayOfMonth);
+				result = DateUtil.beginOfDay(result);
+			} else {
+				result = t;
+			}
+		}
+	}
 }