Java 1.8 不可变且线程安全的日期工具类

/**
 * @author vzhenghuarui
 * @date 2021-05-16 15:25
 */
public class LocalDateDemo {

    public static void main(String[] args) {

        LocalDate localDate = LocalDate.now();//当前日期

        System.out.println("获取今年年份：" + localDate.getYear());
        System.out.println("获取今年月份：" + localDate.getMonthValue());
        System.out.println("获取当月的天数：" + localDate.getDayOfMonth());
        System.out.println("获取今年的天数：" + localDate.getDayOfYear());
        System.out.println("获取今天周几(枚举)：" + localDate.getDayOfWeek());
        System.out.println("获取今天周几(数值)：" + localDate.getDayOfWeek().getValue());


        int year = 1996;
        System.out.println("获取今年日期的年份改为year年的日期：" + localDate.withYear(year));
        int month = 11;
        System.out.println("获取今年日期的月份改为month月的日期：" + localDate.withMonth(month));
        int dayOfMonth = 31;
        System.out.println("获取今年日期的天数改为dayOfMonth天的日期：" + localDate.withDayOfMonth(dayOfMonth));


        Long count = 3L;
        System.out.println("获取今天日期count年之前的日期：" + localDate.minusYears(count));
        int monthCount = 3*12;
        System.out.println("获取今天日期monthCount月之前的日期：" + localDate.minusMonths(monthCount));
        int weekCount = 2;
        System.out.println("获取今天日期weekCount周之前的日期：" + localDate.minusWeeks(weekCount));
        int dayCount = 365;
        System.out.println("获取今天日期dayCount天之前的日期：" + localDate.minusDays(dayCount));


        System.out.println("获取今天日期count年之后的日期：" + localDate.plusYears(count));
        System.out.println("获取今天日期monthCount月之后的日期：" + localDate.plusMonths(monthCount));
        System.out.println("获取今天日期weekCount周之后的日期：" + localDate.plusWeeks(weekCount));
        System.out.println("获取今天日期dayCount天之后的日期：" + localDate.plusDays(dayCount));


        System.out.println("今年是否为润年：" + localDate.isLeapYear());
        System.out.println("今年年份天数：" + localDate.lengthOfYear());
        System.out.println("当月月份天数：" + localDate.lengthOfMonth());
        System.out.println("日期比较：" + localDate.compareTo(localDate));
        System.out.println("是否相等：" + localDate.isEqual(localDate));
        System.out.println("是否在localDate之前：" + localDate.isBefore(localDate));
        System.out.println("是否在localDate之后：" + localDate.isAfter(localDate));

        // localDate 转 String
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
        String date = formatter.format(localDate);
        System.out.println(date);

        // String 转 localDate
        localDate = LocalDate.parse(date,formatter);
        System.out.println(localDate);
    }
}