Java处理日期

前言

JDK8中时间处理类库

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日期格式字符串转日期

• JDK8之前

使用SimpleDateFormat进行转换，但是线程不安全。如下所示

/**
 * 日期格式字符串转日期
 * @param recoure   日期格式字符串
 * @param pattern   日期格式
 *                     
 * @return
 */
public static Date strToDate(String recoure, String pattern) {
    try {
        SimpleDateFormat dateTimeFormat = new SimpleDateFormat(pattern);
        return dateTimeFormat.parse(recoure);
    } catch (Exception e) {
        throw new RuntimeException("parse date error");
    }
}

• JDK8之后

线程安全

/**
 * 日期格式字符串转日期 线程安全
 * @param recoure   日期格式字符串
 * @param pattern   日期格式
 *                     
 * @return
 */
public static Date strToDate8(String recoure, String pattern) {
    try {
        DateTimeFormatter dateTimeFormat = DateTimeFormatter.ofPattern(pattern);
        if ("yyyy-MM-dd".equals(pattern)) {
            return Date.from(LocalDate.parse(recoure,dateTimeFormat)
                    .atStartOfDay()
                    .atZone(ZoneId.systemDefault()).toInstant());
        } else {
            return Date.from(LocalDateTime.parse(recoure,dateTimeFormat)
                    .atZone(ZoneId.systemDefault()).toInstant());
        }
    } catch (Exception e) {
        throw new BusinessException(ResError.SYS_427);
    }
}

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日期转日期格式字符串

• JDK8之前

使用SimpleDateFormat进行转换，但是线程不安全。

/**
 * 日期转日期格式字符串
 * @param date      日期
 * @param pattern   日期格式
 *                     
 * @return
 */
public static String dateToStr(Date date, String pattern) {
    try {
        SimpleDateFormat dateTimeFormat = new SimpleDateFormat(pattern);
        return dateTimeFormat.format(date);
    } catch (Exception e) {
        throw new RuntimeException("parse date error");
    }
}

• JDK8之后

/**
 * LocalDateTime转日期格式字符串 线程安全
 * @param date      日期
 * @param pattern   日期格式
 *                     
 * @return
 */
public static String dateToStr8(LocalDateTime date, String pattern) {
    try {
        DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern(pattern);
        return dateFormat.format(date);
    } catch (Exception e) {
        throw new RuntimeException("parse date error");
    }
}
 
/**
 * 日期转日期格式字符串 线程安全
 * @param date      日期
 * @param pattern   日期格式
 *                     
 * @return
 */
public static String dateToStr8(Date date, String pattern) {
    try {
        DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern(pattern);
        if ("yyyy-MM-dd".equals(pattern)) {
            LocalDate localDate = LocalDateTime
                    .ofInstant(date.toInstant(),ZoneId.systemDefault())
                    .toLocalDate();
            return dateFormat.format(localDate);
        } else {
            LocalDateTime localDateTime = LocalDateTime
                    .ofInstant(date.toInstant(),ZoneId.systemDefault());
            return dateFormat.format(localDateTime);
        }
 
    } catch (Exception e) {
        throw new BusinessException(ResError.SYS_427);
    }
}

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LocalDate、Date、String转换

• Date与LocalDate/LocalDateTime互转

// LocalDateTime转Date
LocalDateTime localDateTime = LocalDateTime.now();
Date date = Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
 
// LocalDate转Date
LocalDate localDate = LocalDate.now();
Date date = Date.from(localDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant());
 
// Date转LocalDateTime
Date date = new Date();
LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(),ZoneId.systemDefault());
 
// Date转LocalDate
Date date = new Date();
LocalDate localDate = LocalDateTime.ofInstant(date.toInstant(),ZoneId.systemDefault()).toLocalDate();

• LocalDate/LocalDateTime与String互转

// LocalDate转String
LocalDate localDate = LocalDate.now();
DateTimeFormatter dateTimeFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd");
String dateStr = localDate.format(dateTimeFormat);
 
// LocalDateTime转String
LocalDateTime localDateTime = LocalDateTime.now();
DateTimeFormatter dateTimeFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String dateStr = localDateTime.format(dateTimeFormat);
 
// String转LocalDate
String dateStr = "2022-11-07";
DateTimeFormatter dateTimeFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate localDate = LocalDate.parse(dateStr,dateTimeFormat);
 
// String转LocalDateTime
String dateStr = "2022-11-07 12:00:00";
DateTimeFormatter dateTimeFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime localDateTime = LocalDateTime.parse(dateStr,dateTimeFormat);

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时间加减

• JDK8之前

Jdk1.1 之后, 带来了java.util.Calendar工具类, 用于处理时间，格式为【Calendar.getInstance().add(int field, int amount)】；

field为Calendar.DATE表示加减的是天，为Calendar.MONTH表示加减的是月，等；

amount表示加减的日期数，正数表示日期加，负数表示日期减，如下：

// 三天前
Calendar calendar1 = Calendar.getInstance();
calendar1.add(Calendar.DATE, -3);
System.out.println(calendar1.getTime());
// 三天后
Calendar calendar2 = Calendar.getInstance();
calendar2.add(Calendar.DATE, 3);
System.out.println(calendar2.getTime());
// 三分钟后
Calendar calendar3 = Calendar.getInstance();
calendar3.add(Calendar.MINUTE, 3);
System.out.println(calendar3.getTime());
// 三小时后
Calendar calendar4 = Calendar.getInstance();
calendar4.add(Calendar.HOUR, 3);
System.out.println(calendar4.getTime());
// 三月后
Calendar calendar5 = Calendar.getInstance();
calendar5.add(Calendar.MONTH, 3);
System.out.println(calendar5.getTime());

操作结果：

Fri Nov 04 11:06:14 CST 2022
Thu Nov 10 11:06:14 CST 2022
Mon Nov 07 11:09:14 CST 2022
Mon Nov 07 14:06:14 CST 2022
Tue Feb 07 11:06:14 CST 2023

• JDK8之后

直接使用LocalDateTime自带的方法即可，如下所示

DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime now = LocalDateTime.now();
System.out.println("当前时间："+ now.format(format));
LocalDateTime plusTime = now.plusMonths(1).plusDays(1).plusHours(1).plusMinutes(1).plusSeconds(1);
System.out.println("增加1月1天1小时1分钟1秒时间后：" + plusTime.format(format));
LocalDateTime minusTime = now.minusMonths(1).minusDays(1).minusHours(1).minusMinutes(1).minusSeconds(1);
System.out.println("减去1月1天1小时1分钟1秒时间后：" + minusTime.format(format));

操作结果：

当前时间：2022-11-07 11:14:26
增加1月1天1小时1分钟1秒时间后：2022-12-08 12:15:27
减去1月1天1小时1分钟1秒时间后：2022-10-06 10:13:25

---

时间比较

LocalDateTime now = LocalDateTime.now();
LocalDateTime yesterday = now.minusDays(1);
System.out.println(now + "在" + yesterday + "之后吗?" + now.isAfter(yesterday));
System.out.println(now + "在" + yesterday + "之前吗?" + now.isBefore(yesterday));
 
// 时间差
long day = yesterday.until(now, ChronoUnit.DAYS);
long month = yesterday.until(now, ChronoUnit.MONTHS);
long hours = yesterday.until(now, ChronoUnit.HOURS);
long minutes = yesterday.until(now, ChronoUnit.MINUTES);
System.out.println("相差月份" + month);
System.out.println("相差天数" + day);
System.out.println("相差小时" + hours);
System.out.println("相差分钟" + minutes);

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时间扩展方法

• JDK8之前

/**
 * 获取上周周一（第一天是周一）
 *
 * @return
 */
public static Date getPreviousMonday() {
    Calendar cal = Calendar.getInstance();
    // 将每周第一天设为星期一，默认是星期天
    cal.setFirstDayOfWeek(Calendar.MONDAY);
    cal.add(Calendar.DATE, -1 * 7);
    cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
 
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);
    return cal.getTime();
}
 
/**
 * 获取上周周日（第一天是周一）
 * @return
 */
public static Date getLastSunday() {
    Calendar cal = Calendar.getInstance();
    //将每周第一天设为星期一，默认是星期天
    cal.setFirstDayOfWeek(Calendar.MONDAY);
    cal.add(Calendar.DATE, -1*7);
    cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
 
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);
    return cal.getTime();
}

• JDK8之后

LocalDateTime now = LocalDateTime.now();
System.out.println("当前时间：" + now);
// 当天最后一秒
LocalDateTime lastSecondOfDay = now.withHour(23).withMinute(59).withSecond(59);
System.out.println("当天最后一秒：" + lastSecondOfDay);
// 本月第一天
LocalDateTime firstDay = now.withDayOfMonth(1);
System.out.println("本月第一天：" + firstDay);
// 本月最后一天
LocalDateTime lastDay = now.with(TemporalAdjusters.lastDayOfMonth());
System.out.println("本月最后一天:" + lastDay);
// 今日所在周的周一
LocalDateTime monday = now.with(TemporalAdjusters.previous(DayOfWeek.SUNDAY)).plusDays(1).withHour(0).withMinute(0).withSecond(0);
System.out.println("今日所在周的周一:" + monday);
// 今日所在周的周二
LocalDateTime tuesday = now.with(TemporalAdjusters.previous(DayOfWeek.SUNDAY)).plusDays(2).withHour(0).withMinute(0).withSecond(0);
System.out.println("今日所在周的周二:" + tuesday);
// 今日所在周的周日
LocalDateTime sunday = now.with(TemporalAdjusters.next(DayOfWeek.MONDAY)).minusDays(1).withHour(23).withMinute(59).withSecond(59);
System.out.println("今日所在周的周日:" + sunday);
// 今日所在周的上周一
LocalDateTime lastMonday = now.with(TemporalAdjusters.previous(DayOfWeek.MONDAY));
System.out.println("今日所在周的上周一:" + lastMonday);
// 是否闰年
System.out.println("今年是否闰年：" + Year.isLeap(now.getYear()));

操作结果：

当前时间：2022-11-07T11:40:20.377
当天最后一秒：2022-11-07T23:59:59.377
本月第一天：2022-11-01T11:40:20.377
本月最后一天:2022-11-30T11:40:20.377
今日所在周的周一:2022-11-07T00:00:00.377
今日所在周的周二:2022-11-08T00:00:00.377
今日所在周的周日:2022-11-13T23:59:59.377
今日所在周的上周一:2022-10-31T11:40:20.377
今年是否闰年：false

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获取上/下一个分钟值以0或者5结尾的时间点

/**
 * 获取下一个分钟值以0或者5结尾的时间点(单位：毫秒)
 * @return
 */
public static long getNextMillisEndWithMinute0or5(Date baseTime) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(baseTime);
    int minute = calendar.get(Calendar.MINUTE);
    if (minute < 55) {
        int add = minute%10 < 5? 5 - minute%10 : 10 - minute%10;
        calendar.add(Calendar.MINUTE,add);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTime().getTime();
    }
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
    Date endTime = DateUtils.addHours(calendar.getTime(), 1);
    return endTime.getTime();
}
 
/**
 * 获取上一个分钟值以0或者5结尾的时间点(单位：毫秒)
 * @return
 */
public static long getLastMillisEndWithMinute0or5(Date baseTime) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(baseTime);
    int minute = calendar.get(Calendar.MINUTE);
    if (minute < 55) {
        int add = minute%10 < 5? 5 - minute%10 : 10 - minute%10;
        calendar.add(Calendar.MINUTE, -(5-add));
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTime().getTime();
    }
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
    Date endTime = DateUtils.addHours(calendar.getTime(), 1);
    return endTime.getTime();
}
 
public static String getNextStrTimeEndWithMinute0or5(Date date, String format) {
    if(StringUtil.isEmpty(format)){
        format = "yyyy-MM-dd HH:mm:ss";
    }
    return DateFormatUtils.format(getNextMillisEndWithMinute0or5(date),format);
}
 
public static String getLastStrTimeEndWithMinute0or5(Date date, String format) {
    if(StringUtil.isEmpty(format)){
        format = "yyyy-MM-dd HH:mm:ss";
    }
    return DateFormatUtils.format(getLastMillisEndWithMinute0or5(date),format);
}

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