1. 删除 DateTimeTools 中的格式化器的缓存，应由调用方执行负责维护；

2. 新增 toYearString 和 toMonthString 方法。

src/main/java/xyz/zhouxy/plusone/commons/util/DateTimeTools.java

@@ -21,19 +21,17 @@ import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.LocalTime;
 import java.time.Month;
+import java.time.Year;
 import java.time.YearMonth;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
-import java.time.format.DateTimeFormatter;
+import java.time.chrono.IsoChronology;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.TimeZone;
 
-import javax.annotation.Nonnull;
+import com.google.common.base.Strings;
-
+import com.google.common.collect.Range;
-import com.google.common.cache.CacheBuilder;
-import com.google.common.cache.CacheLoader;
-import com.google.common.cache.LoadingCache;
 
 import xyz.zhouxy.plusone.commons.time.Quarter;
 import xyz.zhouxy.plusone.commons.time.YearQuarter;
@@ -45,89 +43,32 @@ import xyz.zhouxy.plusone.commons.time.YearQuarter;
  */
 public class DateTimeTools {
 
-    /**
-     * 缓存时间格式化器
-     */
-    private static final LoadingCache<String, DateTimeFormatter> DATE_TIME_FORMATTER_CACHE = CacheBuilder.newBuilder()
-            .maximumSize(20)
-            .build(new CacheLoader<String, DateTimeFormatter>() {
-                @Override
-                public DateTimeFormatter load(@Nonnull String pattern) throws Exception {
-                    return DateTimeFormatter.ofPattern(pattern);
-                }
-            });
-
-    /**
-     * 获取时间格式化器
-     *
-     * @param pattern 时间格式
-     * @return 时间格式化器
-     */
-    public static DateTimeFormatter getDateTimeFormatter(String pattern) {
-        return DATE_TIME_FORMATTER_CACHE.getUnchecked(pattern);
-    }
-
     // #region - toString
 
-    /**
+    public static String toYearString(int year) {
-     * 将日期时间转换为指定格式的字符串
+        return Integer.toString(year);
-     *
-     * @param pattern  时间格式
-     * @param dateTime 日期时间
-     * @return 格式化的字符串
-     */
-    public static String toString(String pattern, ZonedDateTime dateTime) {
-        return getDateTimeFormatter(pattern).format(dateTime);
     }
 
-    /**
+    public static String toYearString(Year year) {
-     * 将时间戳转换为指定格式的字符串，使用系统默认时区
+        return year.toString();
-     *
-     * @param pattern 时间格式
-     * @param instant 时间戳
-     * @return 格式化的字符串
-     */
-    public static String toString(String pattern, Instant instant) {
-        ZonedDateTime dateTime = instant.atZone(ZoneId.systemDefault());
-        return toString(pattern, dateTime);
     }
 
-    /**
+    public static String toMonthString(int monthValue) {
-     * 将时间戳转换为指定格式的字符串，使用指定时区
+        return Strings.padStart(Integer.toString(monthValue), 2, '0');
-     *
-     * @param pattern 时间格式
-     * @param instant 时间戳
-     * @param zone    时区
-     * @return 格式化的字符串
-     */
-    public static String toString(String pattern, Instant instant, ZoneId zone) {
-        ZonedDateTime dateTime = instant.atZone(zone);
-        return toString(pattern, dateTime);
     }
 
-    // #endregion
+    public static String toMonthString(int monthValue, boolean padStart) {
-
+        return padStart ? toMonthString(monthValue) : Integer.toString(monthValue);
-    // #region - nowStr
-
-    /**
-     * 指定格式，返回当前时间戳对应的字符串
-     *
-     * @param pattern 时间格式
-     * @return 格式化的字符串
-     */
-    public static String nowStr(String pattern) {
-        return toString(pattern, ZonedDateTime.now());
     }
 
-    /**
+    public static String toMonthString(Month month) {
-     * 指定格式，返回当前时间戳对应的字符串，使用指定时区
+        final int monthValue = month.getValue();
-     *
+        return Strings.padStart(Integer.toString(monthValue), 2, '0');
-     * @param pattern 时间格式
+    }
-     * @param zone    时区
+
-     * @return 格式化的字符串
+    public static String toMonthString(Month month, boolean padStart) {
-     */
+        final int monthValue = month.getValue();
-    public static String nowStr(String pattern, ZoneId zone) {
+        return padStart ? toMonthString(month) : Integer.toString(monthValue);
-        return toString(pattern, Instant.now().atZone(zone));
     }
 
     // #endregion
@@ -708,6 +649,42 @@ public class DateTimeTools {
 
     // #endregion
 
+    // ================================
+    // #region - others
+    // ================================
+
+    public static LocalDate startDateOfYear(int year) {
+        return LocalDate.ofYearDay(year, 1);
+    }
+
+    public static LocalDate endDateOfYear(int year) {
+        return LocalDate.of(year, 12, 31);
+    }
+
+    public static LocalDateTime startOfNextDate(LocalDate date) {
+        return date.plusDays(1L).atStartOfDay();
+    }
+
+    public static ZonedDateTime startOfNextDate(LocalDate date, ZoneId zone) {
+        return date.plusDays(1L).atStartOfDay(zone);
+    }
+
+    public static Range<LocalDateTime> toDateTimeRange(LocalDate date) {
+        return Range.closedOpen(date.atStartOfDay(), startOfNextDate(date));
+    }
+
+    public static Range<ZonedDateTime> toDateTimeRange(LocalDate date, ZoneId zone) {
+        return Range.closedOpen(date.atStartOfDay(zone), startOfNextDate(date, zone));
+    }
+
+    public static boolean isLeapYear(int year) {
+        return IsoChronology.INSTANCE.isLeapYear(year);
+    }
+
+    // ================================
+    // #endregion - others
+    // ================================
+
     /**
      * 私有构造方法，明确标识该常量类的作用。
      */

src/test/java/xyz/zhouxy/plusone/commons/util/DateTimeToolsTests.java

@@ -20,6 +20,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.time.Instant;
 import java.time.LocalDateTime;
+import java.time.Month;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
@@ -32,13 +33,6 @@ class DateTimeToolsTests {
 
     private static final Logger log = LoggerFactory.getLogger(DateTimeToolsTests.class);
 
-    @Test
-    void testLocalNowStr() {
-        String nowStr = DateTimeTools.nowStr("yyyy/MM/dd HH:mm:ss.SSS");
-        log.info(nowStr);
-        assertEquals(23, nowStr.length());
-    }
-
     @Test
     void testToJoda() {
         LocalDateTime dt = LocalDateTime.of(2008, 8, 8, 20, 18, 59, 108000000);
@@ -55,7 +49,8 @@ class DateTimeToolsTests {
     void testToInstant() {
         ZonedDateTime dt = ZonedDateTime.of(2008, 1, 8, 10, 23, 50, 108000000, ZoneId.systemDefault());
         Instant instant = DateTimeTools.toInstant(dt.toInstant().toEpochMilli());
-        String str = DateTimeTools.toString("yy-M-d HH:mm:ss.SSS", instant);
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yy-M-d HH:mm:ss.SSS");
+        String str = formatter.format(instant.atZone(ZoneId.systemDefault()));
         log.info(str);
         assertEquals("08-1-8 10:23:50.108", str);
     }
@@ -107,4 +102,11 @@ class DateTimeToolsTests {
         log.info("{}", formatter);
         log.info("{}", formatter2);
     }
+
+    @Test
+    void testToString() {
+        assertEquals("04", DateTimeTools.toMonthString(Month.APRIL));
+        assertEquals("04", DateTimeTools.toMonthString(Month.APRIL, true));
+        assertEquals("4", DateTimeTools.toMonthString(Month.APRIL, false));
+    }
 }