Java8 新特性LocalDate 線程安全的時間處理類

Java8 新特性中推出了日期處理類LocalDate，實在是太方便了，主要用到是下面的3個類。

java.time.LocalDate ->只對年月日做出處理

java.time.LocalTime ->只對時分秒納秒做出處理

java.time.LocalDateTime ->同時可以處理年月日和時分秒

優點：

除了使用起來更加簡單和靈活，主要是傳統的時期處理類Date、Calendar不是多線程安全的，而LocalDate 線程安全的，所以不用擔心併發問題。下面是我的實戰代碼：

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.google.common.collect.Lists;

/**
 *
 *
 * Java 8 的時間工具類
 */
public class DateUtils {

    /**
     * 默認使用系統當前時區
     */
    private static final ZoneId ZONE = ZoneId.systemDefault();

    private static final String DATE_FORMAT = "yyyy-MM-dd";

    private static final String DATE_FORMAT_DS = "yyyyMMdd";

    private static final String DATE_FORMAT_DEFAULT = "yyyy-MM-dd HH:mm:ss";

    private static final String TIME_FORMAT = "yyyyMMddHHmmss";

    private static final String REGEX = "\\:|\\-|\\s";

    public static final DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    /**
     * 獲取當前時間
     *
     * @param format
     * @return
     */
    public static String getCurrentTime(String format) {

        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);

        LocalDateTime now = LocalDateTime.now();

        return now.format(dateTimeFormatter);

    }

    /**
     * 獲取昨日時間
     *
     * @param format
     * @return
     */
    public static String getYesterday(String format) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate nowDate = LocalDate.now();
        LocalDate yesterday = nowDate.minusDays(1);
        return yesterday.format(dateTimeFormatter);

    }

    /**
     * 獲取上週的時間
     *
     * @param format
     * @return
     */
    public static String getLastWeek(String format) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate nowDate = LocalDate.now();
        LocalDate lastWeek = nowDate.minusWeeks(1);
        return lastWeek.format(dateTimeFormatter);
    }

    /**
     * 獲取上個月的時間
     *
     * @param format
     * @return
     */
    public static String getLastMonth(String format) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate nowDate = LocalDate.now();
        LocalDate lastMonth = nowDate.minusMonths(1);
        return lastMonth.format(dateTimeFormatter);

    }

    /**
     * 獲取去年的時間
     *
     * @param format
     * @return
     */
    public static String getLastYear(String format) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate nowDate = LocalDate.now();
        LocalDate lastYear = nowDate.minusYears(1);
        return lastYear.format(dateTimeFormatter);
    }

    /**
     * 獲取前多少天的日期
     *
     * @param format
     * @param num
     * @return
     */
    public static String getBeforeSomeDay(String format, int num) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate nowDate = LocalDate.now();
        LocalDate beforeDay = nowDate.minusDays(num);
        return beforeDay.format(dateTimeFormatter);
    }

    /**
     * 獲取指定時間的前多少天
     *
     * @param format
     * @param date
     * @param num
     * @return
     */
    public static String getBeforeDayOfDate(String format, String date, int num) {

        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate localDate = LocalDate.parse(date, dateTimeFormatter);
        LocalDate beforeDay = localDate.minusDays(num);
        return beforeDay.format(dateTimeFormatter);

    }

    /**
     * 獲取當天的開始時間  yyyy-MM-dd 00:00:00
     *
     * @param format
     * @return
     */
    public static String getDayStartTime(String format, String date) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate localDate = LocalDate.parse(date, dateTimeFormatter);
        LocalDateTime toDayStart = LocalDateTime.of(localDate, LocalTime.MIN);
        return toDayStart.format(FORMATTER);
    }

    /**
     * 獲取當天的結束時間 yyyy-MM-dd 23:59:59
     *
     * @param format
     * @return
     */
    public static String getDayEndTime(String format, String date) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(format);
        LocalDate localDate = LocalDate.parse(date, dateTimeFormatter);
        LocalDateTime toDayStart = LocalDateTime.of(localDate, LocalTime.MAX);
        return toDayStart.format(FORMATTER);
    }

    /**
     * 獲取兩個時間之間的間隔天數
     *
     * @param startDate yyyyMMdd
     * @param endDate   yyyyMMdd
     * @return
     */
    public static long getRangeCountOfDate(String startDate, String endDate) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_FORMAT_DS);
        LocalDate startLocalDate = LocalDate.parse(startDate, dateTimeFormatter);
        LocalDate endLocalDate = LocalDate.parse(endDate, dateTimeFormatter);
        long count = ChronoUnit.DAYS.between(startLocalDate, endLocalDate);
        return count;

    }

    /**
     * 後期兩個時間之間的所有日期 【包含開始時間和結束時間】
     *
     * @param startDate yyyyMMdd
     * @param endDate   yyyyMMdd
     * @return
     */
    public static List<String> getRangeOfDate(String startDate, String endDate) {
        List<String> range = Lists.newArrayList();
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_FORMAT_DS);
        LocalDate startLocalDate = LocalDate.parse(startDate, dateTimeFormatter);
        LocalDate endLocalDate = LocalDate.parse(endDate, dateTimeFormatter);
        long count = ChronoUnit.DAYS.between(startLocalDate, endLocalDate);
        if (count < 0) {
            return range;
        }

        range = Stream.iterate(startLocalDate, d -> d.plusDays(1)).limit(count + 1).map(
            s -> s.format(dateTimeFormatter)).collect(Collectors.toList());
        return range;
    }

    public static void main(String[] args) {
        System.out.println(getRangeOfDate("20191010", "20191020"));
    }

}