java8 LocalDateTime 工具類

參考連接1：java8時間類LocalDateTime

參考連接2：如何在Java 8中愉快地處理日期和時間

參考連接3：Java Date Time - Custom Date Format Patterns

import java.time.DayOfWeek;
import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Period;
import java.time.format.DateTimeFormatter;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAdjusters;

public class DateTimeUtils {

    public static final DateTimeFormatter DATETIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    public static final DateTimeFormatter MONTH_FORMATTER    = DateTimeFormatter.ofPattern("yyyy-MM");
    public static final DateTimeFormatter DATE_FORMATTER     = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    public static final DateTimeFormatter TIME_FORMATTER     = DateTimeFormatter.ofPattern("HH:mm:ss");

    public static LocalDate parseLocalDate(String dateStr) {
        return LocalDate.parse(dateStr, DATE_FORMATTER);
    }

    public static LocalDateTime parseLocalDateTime(String dateTimeStr) {
        return LocalDateTime.parse(dateTimeStr, DATETIME_FORMATTER);
    }

    public static LocalTime parseLocalTime(String timeStr) {
        return LocalTime.parse(timeStr, TIME_FORMATTER);
    }

    public static String formatLocalDate(LocalDate date) {
        return date.format(DATE_FORMATTER);
    }

    public static String formatLocalDateTime(LocalDateTime datetime) {
        return datetime.format(DATETIME_FORMATTER);
    }

    public static String formatLocalTime(LocalTime time) {
        return time.format(TIME_FORMATTER);
    }

    /**
     * 日期相隔天數
     * @param startDateInclusive
     * @param endDateExclusive
     * @return
     */
    public static int periodDays(LocalDate startDateInclusive, LocalDate endDateExclusive) {
        return Period.between(startDateInclusive, endDateExclusive).getDays();
    }

    /**
     * 日期相隔小時
     * @param startInclusive
     * @param endExclusive
     * @return
     */
    public static long durationHours(Temporal startInclusive, Temporal endExclusive) {
        return Duration.between(startInclusive, endExclusive).toHours();
    }

    /**
     * 日期相隔分鐘
     * @param startInclusive
     * @param endExclusive
     * @return
     */
    public static long durationMinutes(Temporal startInclusive, Temporal endExclusive) {
        return Duration.between(startInclusive, endExclusive).toMinutes();
    }

    /**
     * 日期相隔毫秒數
     * @param startInclusive
     * @param endExclusive
     * @return
     */
    public static long durationMillis(Temporal startInclusive, Temporal endExclusive) {
        return Duration.between(startInclusive, endExclusive).toMillis();
    }

    /**
     * 返回當前的日期
     * @return
     */
    public static LocalDate getCurrentLocalDate() {
        return LocalDate.now();
    }

    /**
     * 返回當前時間
     * @return
     */
    public static LocalTime getCurrentLocalTime() {
        return LocalTime.now();
    }

    public static LocalDateTime get() {
        return LocalDateTime.now();
    }

    public static int getYear() {
        return get().getYear();
    }

    public static LocalDateTime withYear(int year) {
        return get().withYear(year);
    }

    public static int getMonth() {
        return get().getMonthValue();
    }

    public static LocalDateTime firstDayOfThisYear(int year) {
        return withYear(year).with(TemporalAdjusters.firstDayOfYear()).with(LocalTime.MIN);
    }

    /**
     * @Title: getFirstDayOfThisYear
     * @Description: 獲取設置所屬年最初時間
     * @param year
     * @return String
     */
    public static String getFirstDayOfThisYear(int year) {
        LocalDateTime firstDayOfThisYear = firstDayOfThisYear(year);
        return DATETIME_FORMATTER.format(firstDayOfThisYear);
    }

    public static LocalDateTime lastDayOfThisYear(int year) {
        return withYear(year).with(TemporalAdjusters.lastDayOfYear()).with(LocalTime.MAX);
    }

    /**
     * @Title: getLastDayOfThisYear
     * @Description: 獲取設置所屬年最後時間
     * @param year
     * @return String
     */
    public static String getLastDayOfThisYear(int year) {
        LocalDateTime lastDayOfThisYear = lastDayOfThisYear(year);
        return DATETIME_FORMATTER.format(lastDayOfThisYear);
    }

    /**
     * @Title: getFirstDayOfThisMonth
     * @Description: 獲取本月的第一天
     * @return String
     */
    public static String getFirstDayOfThisMonth() {
        LocalDateTime firstDayOfThisYear = get().with(TemporalAdjusters.firstDayOfMonth());
        return DATETIME_FORMATTER.format(firstDayOfThisYear);
    }

    /**
     * @Title: getFirstDayOfThisMonth
     * @Description: 獲取本月的最末天
     * @return String
     */
    public static String getLastDayOfThisMonth() {
        LocalDateTime firstDayOfThisYear = get().with(TemporalAdjusters.lastDayOfMonth());
        return DATETIME_FORMATTER.format(firstDayOfThisYear);
    }

    /**
     * @Title: plusDays
     * @Description: 當前日期向後推多少天
     * @param day
     * @return LocalDateTime
     */
    public static LocalDateTime plusDays(int days) {
        return get().plusDays(days);
    }

    /**
     * @Title: firstDayOfWeekInYearMonth
     * @Description: 獲取指定年月的第一個週一
     * @param year
     * @param month
     * @return LocalDateTime
     */
    public static LocalDateTime firstDayOfWeekInYearMonth(int year, int month) {
        return get().withYear(year).withMonth(month).with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
    }

    /**
     * @Title: todayStart
     * @Description: 當天開始時間
     * @return LocalDateTime
     */
    public static LocalDateTime todayStart() {
        return LocalDateTime.of(getCurrentLocalDate(), LocalTime.MIN);
    }

    /**
     * @Title: todayEnd
     * @Description: 當天結束時間
     * @return LocalDateTime
     */
    public static LocalDateTime todayEnd() {
        return LocalDateTime.of(getCurrentLocalDate(), LocalTime.MAX);
    }

    /**
     * @Title: getStartDayOfWeekToString
     * @Description: 獲取周第一天
     * @return String
     */
    public static String getStartDayOfWeekToString() {
        return formatLocalDate(getStartDayOfWeek());
    }

    public static LocalDate getStartDayOfWeek() {
        TemporalAdjuster FIRST_OF_WEEK = TemporalAdjusters.ofDateAdjuster(localDate -> localDate.minusDays(localDate
                .getDayOfWeek().getValue() - DayOfWeek.MONDAY.getValue()));
        return getCurrentLocalDate().with(FIRST_OF_WEEK);
    }

    /**
     * @Title: getEndDayOfWeekToString
     * @Description: 獲取周最後一天
     * @return String
     */
    public static String getEndDayOfWeekToString() {
        return formatLocalDate(getEndDayOfWeek());
    }
	
	/**     
     * @Description: 當前開始時間
     * @return LocalDateTime
     */
	public static LocalDateTime getNow() {
        return LocalDateTime.of(LocalDate.now(), LocalTime.MIDNIGHT);
    }
	
	/**     
     * @Description: 指定時間添加一週
     * @return LocalDateTime
     */
	public static LocalDateTime minusOneWeek(LocalDateTime now) {
        return now.minus(1, ChronoUnit.WEEKS);
    }

    public static LocalDate getEndDayOfWeek() {
        TemporalAdjuster LAST_OF_WEEK = TemporalAdjusters.ofDateAdjuster(localDate -> localDate.plusDays(
                DayOfWeek.SUNDAY.getValue() - localDate.getDayOfWeek().getValue()));
        return getCurrentLocalDate().with(LAST_OF_WEEK);
    }	

    public static String formatLocalDateTime(LocalDateTime datetime) {
        return datetime.format(DATETIME_FORMATTER);
    }

    public static String formatLocalDateTime() {
        return formatLocalDateTime(LocalDateTime.now());
    }

    public static LocalDateTime date2LocalDateTime(Date date) {
        if (date == null) {
            return null;
        }
        Instant instant = date.toInstant();
        return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
    }
    
    public static Date localDateTime2Date(LocalDateTime localDateTime) {
        if (localDateTime == null) {
            return null;
        }
        return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
    }

    public static void main(String[] args) {
        //
        Integer year = 2019;
        System.out.println(getFirstDayOfThisYear(year));
        System.out.println(getLastDayOfThisYear(year));
        //
        System.out.println(DATETIME_FORMATTER.format(plusDays(1)));
        System.out.println(DATETIME_FORMATTER.format(plusDays(-1)));

        // 取第一個週一
        LocalDate ld = LocalDate.parse("2019-01-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
        System.out.println(DATE_FORMATTER.format(ld));
        //
        System.out.println(DATETIME_FORMATTER.format(firstDayOfWeekInYearMonth(year, 3)));
        System.out.println("-------------------");
        // new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format();
        System.out.println(getStartDayOfWeekToString());
        System.out.println(getEndDayOfWeekToString());
        System.out.println("-------------------");
        System.out.println(DATETIME_FORMATTER.format(todayStart()));
        System.out.println(DATETIME_FORMATTER.format(todayEnd()));
    }

}