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Java日期格式化如何避免YYYY引發(fā)的時(shí)間異常

更新時(shí)間：2023年11月16日 10:31:15 作者：myprince003

在編程中,日期格式化是一個(gè)常見(jiàn)的任務(wù),使用不同的格式化選項(xiàng)可能會(huì)導(dǎo)致一些意外的結(jié)果,下面我們就來(lái)學(xué)習(xí)一下Java如何避免YYYY引發(fā)的時(shí)間異常吧

在編程中，日期格式化是一個(gè)常見(jiàn)的任務(wù)。使用不同的格式化選項(xiàng)可能會(huì)導(dǎo)致一些意外的結(jié)果。最近遇到一個(gè)問(wèn)題，就是使用YYYY格式化選項(xiàng)會(huì)導(dǎo)致時(shí)間異常。

public static void main(String[] args) throws ParseException {

    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    SimpleDateFormat sdf2 = new SimpleDateFormat("YYYY-MM-dd HH:mm:ss");
   
    String time = "2023-12-31 23:59:59";
    System.out.printf("yyyy-MM-dd HH:mm:ss: %s\n",sdf.format(sdf.parse(time)));
    System.out.printf("YYYY-MM-dd HH:mm:ss: %s\n",sdf2.format(sdf2.parse(time)));

    System.out.println("======================================");
    String time2 = "2023-11-31 23:59:59"; //11月沒(méi)有31號(hào)
    System.out.printf("yyyy-MM-dd HH:mm:ss: %s\n",sdf.format(sdf.parse(time2)));
    System.out.printf("YYYY-MM-dd HH:mm:ss: %s\n",sdf2.format(sdf2.parse(time2)));

    System.out.println("======================================");
    String time3 = "2023-10-31 23:59:59";
    System.out.printf("yyyy-MM-dd HH:mm:ss: %s\n",sdf.format(sdf.parse(time3)));
    System.out.printf("YYYY-MM-dd HH:mm:ss: %s\n",sdf2.format(sdf2.parse(time3)));
}

輸出結(jié)果

yyyy-MM-dd HH:mm:ss: 2023-12-31 23:59:59
YYYY-MM-dd HH:mm:ss: 2023-01-01 23:59:59
======================================
yyyy-MM-dd HH:mm:ss: 2023-12-01 23:59:59
YYYY-MM-dd HH:mm:ss: 2023-01-01 23:59:59
======================================
yyyy-MM-dd HH:mm:ss: 2023-10-31 23:59:59
YYYY-MM-dd HH:mm:ss: 2023-01-01 23:59:59

網(wǎng)上查閱說(shuō)大寫(xiě)的YYYY表示一個(gè)基于周的年份，它是根據(jù)周計(jì)算的年份，而不是基于日歷的年份。通常情況下，兩者的結(jié)果是相同的，但在跨年的第一周或最后一周可能會(huì)有差異。但這里發(fā)現(xiàn)無(wú)論怎么調(diào)整時(shí)間，YYYY-MM-dd HH:mm:ss格式化后一直是2023-01-01 23:59:59，不僅僅是在跨年的時(shí)候出現(xiàn)問(wèn)題，具體原因尚不清楚

如何避免

定義通用的格式類，所有使用日期格式的地方都引用這個(gè)類，這個(gè)類中就定義好yyyy-MM-dd格式即可，這樣就不會(huì)出現(xiàn)有人手誤給大家埋雷了。

public class LocalDateUtils {

    /**
     * 顯示年月日時(shí)分秒，例如 2023-10-31 09:51:53.
     */
    public static final String DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";

    /**
     * 僅顯示年月日，例如 2023-10-31.
     */
    public static final String DATE_PATTERN = "yyyy-MM-dd";

    private static final String YEAR = "year";
    private static final String MONTH = "month";
    private static final String WEEK = "week";
    private static final String DAY = "day";

    /**
     * 將日期轉(zhuǎn)換為字符串，格式為：yyyy-MM-dd HH:mm:ss
     */
    public static String getLocalDateTimeStr(LocalDateTime localDateTime) {
        return format(localDateTime, DATETIME_PATTERN);
    }

    /**
     * 將日期轉(zhuǎn)換為字符串，格式為：yyyy-MM-dd
     */
    public static String getLocalDateStr(LocalDateTime localDateTime) {
        return format(localDateTime, DATE_PATTERN);
    }


    /**
     * 將字符串轉(zhuǎn)換為日期，格式為：yyyy-MM-dd HH:mm:ss
     */
    public static LocalDateTime parseLocalDateTime(String localDateTimeStr) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATETIME_PATTERN);
        return LocalDateTime.parse(localDateTimeStr, dateTimeFormatter);
    }

    /**
     * 將字符串轉(zhuǎn)換為日期，格式為：yyyy-MM-dd
     */
    public static LocalDate parseLocalDate(String localDateStr) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_PATTERN);
        return LocalDate.parse(localDateStr, dateTimeFormatter);
    }


    /**
     * 將字符串轉(zhuǎn)日期成Long類型的時(shí)間戳
     */
    public static Long convertLocalDateTimeToLong(String time) {
        LocalDateTime parse = parse(time, DATETIME_PATTERN);
        return LocalDateTime.from(parse).atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
    }

    /**
     * 將字符串轉(zhuǎn)日期成Long類型的時(shí)間戳
     */
    public static Long convertLocalDateToLong(String time) {
        LocalDateTime parse = parse(time, DATE_PATTERN);
        return LocalDateTime.from(parse).atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
    }

    public static LocalDateTime parse(String time, String pattern) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(pattern);
        return LocalDateTime.parse(time, dateTimeFormatter);
    }


    /**
     * 將Long類型的時(shí)間戳轉(zhuǎn)換成String 類型的時(shí)間格式
     */
    public static String getLocalDateTimeStr(Long time) {
        return format(LocalDateTime.ofInstant(Instant.ofEpochMilli(time), ZoneId.systemDefault()), DATETIME_PATTERN);
    }

    /**
     * 將Long類型的時(shí)間戳轉(zhuǎn)換成String 類型的時(shí)間格式，時(shí)間格式為：yyyy-MM-dd
     */
    public static String getLocalDateStr(Long time) {
        return format(LocalDateTime.ofInstant(Instant.ofEpochMilli(time), ZoneId.systemDefault()), DATE_PATTERN);
    }

    /**
     * 獲取日期時(shí)間字符串
     */
    public static String format(TemporalAccessor temporal, String pattern) {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(pattern);
        return dateTimeFormatter.format(temporal);
    }


    /**
     * 取本月第一天
     */
    public static LocalDate firstDayOfThisMonth() {
        LocalDate today = LocalDate.now();
        return today.with(TemporalAdjusters.firstDayOfMonth());
    }

    /**
     * 取本月第N天
     */
    public static LocalDate dayOfThisMonth(int n) {
        LocalDate today = LocalDate.now();
        return today.withDayOfMonth(n);
    }

    /**
     * 取本月最后一天
     */
    public static LocalDate lastDayOfThisMonth() {
        LocalDate today = LocalDate.now();
        return today.with(TemporalAdjusters.lastDayOfMonth());
    }


    /**
     * 獲取指定日期時(shí)間加上指定數(shù)量日期時(shí)間單位之后的日期時(shí)間.
     */
    public static LocalDateTime plus(LocalDateTime localDateTime, int num, ChronoUnit chronoUnit) {
        return localDateTime.plus(num, chronoUnit);
    }

    /**
     * 獲取指定日期時(shí)間減去指定數(shù)量日期時(shí)間單位之后的日期時(shí)間.
     */
    public static LocalDateTime minus(LocalDateTime localDateTime, int num, ChronoUnit chronoUnit) {
        return localDateTime.minus(num, chronoUnit);
    }

    /**
     * 根據(jù)ChronoUnit計(jì)算兩個(gè)日期時(shí)間之間相隔日期時(shí)間
     */
    public static long getChronoUnitBetween(LocalDateTime start, LocalDateTime end, ChronoUnit chronoUnit) {
        return Math.abs(start.until(end, chronoUnit));
    }

    /**
     * 根據(jù)ChronoUnit計(jì)算兩個(gè)日期之間相隔年數(shù)或月數(shù)或天數(shù)
     */
    public static long getChronoUnitBetween(LocalDate start, LocalDate end, ChronoUnit chronoUnit) {
        return Math.abs(start.until(end, chronoUnit));
    }


    /**
     * 切割日期。按照周期切割成小段日期段。例如： <br>
     *
     * @param startDate 開(kāi)始日期（yyyy-MM-dd）
     * @param endDate   結(jié)束日期（yyyy-MM-dd）
     * @param period    周期（天，周，月，年）
     * @return 切割之后的日期集合
     * <li>startDate="2023-10-27",endDate="2023-10-31",period="day"</li>
     * <li>結(jié)果為：[2023-10-27, 2023-10-28, 2023-10-29, 2023-10-03,2023-10-31]</li><br>
     * <li>startDate="2023-10-27",endDate="2023-10-31",period="week"</li>
     * <li>結(jié)果為：[2023-10-27,2023-10-31]</li><br>
     * <li>startDate="2023-10-27",endDate="2023-10-31",period="month"</li>
     * <li>結(jié)果為：[2023-10-27,2023-10-31]</li><br>
     * <li>startDate="2023-10-27",endDate="2023-10-31",period="year"</li>
     * <li>結(jié)果為：[2023-10-27,2023-10-31]</li><br>
     */
    public static List<String> listDateStrs(String startDate, String endDate, String period) {
        List<String> result = new ArrayList<>();
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_PATTERN);
        LocalDate end = LocalDate.parse(endDate, dateTimeFormatter);
        LocalDate start = LocalDate.parse(startDate, dateTimeFormatter);
        LocalDate tmp = start;
        switch (period) {
            case DAY:
                while (start.isBefore(end) || start.isEqual(end)) {
                    result.add(start.toString());
                    start = start.plusDays(1);
                }
                break;
            case WEEK:
                while (tmp.isBefore(end) || tmp.isEqual(end)) {
                    if (tmp.plusDays(6).isAfter(end)) {
                        result.add(tmp.toString() + "," + end);
                    } else {
                        result.add(tmp.toString() + "," + tmp.plusDays(6));
                    }
                    tmp = tmp.plusDays(7);
                }
                break;
            case MONTH:
                while (tmp.isBefore(end) || tmp.isEqual(end)) {
                    LocalDate lastDayOfMonth = tmp.with(TemporalAdjusters.lastDayOfMonth());
                    if (lastDayOfMonth.isAfter(end)) {
                        result.add(tmp.toString() + "," + end);
                    } else {
                        result.add(tmp.toString() + "," + lastDayOfMonth);
                    }
                    tmp = lastDayOfMonth.plusDays(1);
                }
                break;
            case YEAR:
                while (tmp.isBefore(end) || tmp.isEqual(end)) {
                    LocalDate lastDayOfYear = tmp.with(TemporalAdjusters.lastDayOfYear());
                    if (lastDayOfYear.isAfter(end)) {
                        result.add(tmp.toString() + "," + end);
                    } else {
                        result.add(tmp.toString() + "," + lastDayOfYear);
                    }
                    tmp = lastDayOfYear.plusDays(1);
                }
                break;
            default:
                break;
        }
        return result;
    }
}

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