通过Java日期时间API系列8-----Jdk8中java.time包中的新的日期时间API类的LocalDate源码分析中可以看出，java8中的方法特别丰富，一些常用的计算如星期计算，闰年计算等等。
下面是应用代码：
/** * 获取星期值 1-7，星期一到星期日 * @param date * @return */ public static int getDayOfWeek(Date date){ return DateTimeConverterUtil.toLocalDateTime(date).getDayOfWeek().getValue(); } /** * 获取星期值 1-7，星期一到星期日 * @param localDateTime * @return */ public static int getDayOfWeek(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.getDayOfWeek().getValue(); } /** * 获取星期值 1-7，星期一到星期日 * @param instant * @return */ public static int getDayOfWeek(Instant instant){ return DateTimeConverterUtil.toLocalDateTime(instant).getDayOfWeek().getValue(); } /** * 获取星期值当前月的最后一天 * @param localDate * @return */ public static LocalDate lastDayOfMonth(LocalDate localDate){ Objects.requireNonNull(localDate, "localDate"); return localDate.with(TemporalAdjusters.lastDayOfMonth()); } /** * 获取星期值当前月的最后一天 * @param localDateTime * @return */ public static LocalDateTime lastDayOfMonth(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.with(TemporalAdjusters.lastDayOfMonth()); } /** * 获取星期值当前月的最后一天 * @param date * @return */ public static Date lastDayOfMonth(Date date){ return DateTimeConverterUtil.toDate(DateTimeConverterUtil.toLocalDate(date).with(TemporalAdjusters.lastDayOfMonth())); } /** * 判断是否闰年 * @param localDate * @return */ public static boolean isLeapYear(LocalDate localDate){ Objects.requireNonNull(localDate, "localDate"); return localDate.isLeapYear(); } /** * 判断是否闰年 * @param localDateTime * @return */ public static boolean isLeapYear(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.toLocalDate().isLeapYear(); } /** * 判断是否闰年 * @param date * @return */ public static boolean isLeapYear(Date date){ return DateTimeConverterUtil.toLocalDateTime(date).toLocalDate().isLeapYear(); } /** * 获取月的天数 * @param localDate * @return */ public static int lengthOfMonth(LocalDate localDate){ Objects.requireNonNull(localDate, "localDate"); return localDate.lengthOfMonth(); } /** * 获取月的天数 * @param localDateTime * @return */ public static int lengthOfMonth(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.toLocalDate().lengthOfMonth(); } /** * 获取月的天数 * @param date * @return */ public static int lengthOfMonth(Date date){ return DateTimeConverterUtil.toLocalDateTime(date).toLocalDate().lengthOfMonth(); } /** * 获取年的天数 * @param localDate * @return */ public static int lengthOfYear(LocalDate localDate){ Objects.requireNonNull(localDate, "localDate"); return localDate.lengthOfYear(); } /** * 获取年的天数 * @param localDateTime * @return */ public static int lengthOfYear(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.toLocalDate().lengthOfYear(); } /** * 获取年的天数 * @param date * @return */ public static int lengthOfYear(Date date){ return DateTimeConverterUtil.toLocalDateTime(date).toLocalDate().lengthOfYear(); } /** * 下一个星期几 * @param localDate * @param dayOfWeek * @return */ public static LocalDate next(LocalDate localDate, DayOfWeek dayOfWeek){ Objects.requireNonNull(localDate, "localDate"); return localDate.with(TemporalAdjusters.next(dayOfWeek)); } /** * 下一个星期几 * @param localDateTime * @param dayOfWeek * @return */ public static LocalDateTime next(LocalDateTime localDateTime, DayOfWeek dayOfWeek){ return localDateTime.with(TemporalAdjusters.next(dayOfWeek)); } /** * 下一个星期几 * @param date * @param dayOfWeek * @return */ public static Date next(Date date, DayOfWeek dayOfWeek){ return DateTimeConverterUtil.toDate(DateTimeConverterUtil.toLocalDate(date).with(TemporalAdjusters.next(dayOfWeek))); } /** * 上一个星期几 * @param localDate * @param dayOfWeek * @return */ public static LocalDate previous(LocalDate localDate, DayOfWeek dayOfWeek){ Objects.requireNonNull(localDate, "localDate"); return localDate.with(TemporalAdjusters.previous(dayOfWeek)); } /** * 上一个星期几 * @param localDateTime * @param dayOfWeek * @return */ public static LocalDateTime previous(LocalDateTime localDateTime, DayOfWeek dayOfWeek){ return localDateTime.with(TemporalAdjusters.previous(dayOfWeek)); } /** * 上一个星期几 * @param date * @param dayOfWeek * @return */ public static Date previous(Date date, DayOfWeek dayOfWeek){ return DateTimeConverterUtil.toDate(DateTimeConverterUtil.toLocalDate(date).with(TemporalAdjusters.previous(dayOfWeek))); } /** * 获下一个工作日 * @param localDate * @return */ public static LocalDate nextWorkDay(LocalDate localDate){ Objects.requireNonNull(localDate, "localDate"); return localDate.with(TemporalAdjusterExtension.nextWorkDay()); } /** * 获下一个工作日 * @param localDateTime * @return */ public static LocalDateTime nextWorkDay(LocalDateTime localDateTime){ Objects.requireNonNull(localDateTime, "localDateTime"); return localDateTime.with(TemporalAdjusterExtension.nextWorkDay()); } /** * 获下一个工作日 * @param date * @return */ public static Date nextWorkDay(Date date){ return DateTimeConverterUtil.toDate(DateTimeConverterUtil.toLocalDate(date).with(TemporalAdjusterExtension.nextWorkDay())); }
测试代码：
/** * Date其他常用计算 */ @Test public void dateCalculatorOtherTest(){ Date date = new Date(); System.out.println(date); System.out.println(DateTimeConverterUtil.toLocalDateTime(date)); //获取星期值 System.out.println(DateTimeCalculatorUtil.getDayOfWeek(date)); //获取星期值当前月的最后一天 System.out.println(DateTimeCalculatorUtil.lastDayOfMonth(date)); //判断是否闰年 System.out.println(DateTimeCalculatorUtil.isLeapYear(date)); //获取月的天数 System.out.println(DateTimeCalculatorUtil.lengthOfMonth(date)); //获取月的天数 System.out.println(DateTimeCalculatorUtil.lengthOfYear(date)); //下一个星期一 System.out.println(DateTimeCalculatorUtil.next(date, DayOfWeek.MONDAY)); //上一个星期一 System.out.println(DateTimeCalculatorUtil.previous(date, DayOfWeek.MONDAY)); //获下一个工作日 System.out.println(DateTimeCalculatorUtil.nextWorkDay(date)); } /** * LocalDateTime其他常用计算 */ @Test public void dateCalculatorOtherTest2(){ LocalDateTime ldt = LocalDateTime.now(); System.out.println(ldt); //获取星期值 System.out.println(DateTimeCalculatorUtil.getDayOfWeek(ldt)); //获取星期值当前月的最后一天 System.out.println(DateTimeCalculatorUtil.lastDayOfMonth(ldt)); //判断是否闰年 System.out.println(DateTimeCalculatorUtil.isLeapYear(ldt)); //获取月的天数 System.out.println(DateTimeCalculatorUtil.lengthOfMonth(ldt)); //获取月的天数 System.out.println(DateTimeCalculatorUtil.lengthOfYear(ldt)); //下一个星期一 System.out.println(DateTimeCalculatorUtil.next(ldt, DayOfWeek.MONDAY)); //上一个星期一 System.out.println(DateTimeCalculatorUtil.previous(ldt, DayOfWeek.MONDAY)); //获下一个工作日 System.out.println(DateTimeCalculatorUtil.nextWorkDay(ldt)); }
测试结果：
Fri Feb 07 18:34:40 CST 2020 2020-02-07T18:34:40.887 5 Sat Feb 29 00:00:00 CST 2020 true 29 366 Mon Feb 10 00:00:00 CST 2020 Mon Feb 03 00:00:00 CST 2020 Mon Feb 10 00:00:00 CST 2020 2020-02-07T18:34:56.421 5 2020-02-29T18:34:56.421 true 29 366 2020-02-10T18:34:56.421 2020-02-03T18:34:56.421 2020-02-10T18:34:56.421