LocalDate & LocalDateTime 常用 API 互相转换

Java LocalDate LocalDateTime
在平常时开发过程中，总有很多奇奇怪怪的时间需要互相转换，比如 Date to String , Date to DateTime、String to Date、String to DateTime、Date to TimeStamp等等。

1、LocalDateTime to String(将LocalDateTime 转为自定义的时间格式字符串

public static String localDateTimeToString(LocalDateTime localDateTime, String format) {
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
    return localDateTime.format(formatter);
}

2、timestamp to LocalDateTime (将long类型的timeStamp转为LocalDateTime )

public static LocalDateTime timestampToLocalDateTime(long timestamp) {
    Instant instant = Instant.ofEpochMilli(timestamp);
    ZoneId zone = ZoneId.systemDefault();
    return LocalDateTime.ofInstant(instant, zone);
}

3、LocalDateTime to timestamp ( 将LocalDateTime转为long类型的timeStamp )

public static long localDateTimeToTimestamp(LocalDateTime localDateTime) {
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    return instant.toEpochMilli();
}

4、LocalDateTime to Date ( 将LocalDateTime to Date )

public static Date localDateTimeToDate(LocalDateTime localDateTime) {
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    return Date.from(instant);
}

5、String to 自定义格式 ( Formatter ) 的LocalDateTime ( 将时间字符串转为自定义格式的LocalDateTime )

public static LocalDateTime parseStringToDateTime(String time, String format) {
    DateTimeFormatter df = DateTimeFormatter.ofPattern(format);
    return LocalDateTime.parse(time, df);
}

6、Date to LocalDateTime ( 将Date转为LocalDateTime )

public static LocalDateTime dateToLocalDateTime(Date date) {
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    return LocalDateTime.ofInstant(instant, zone);
}

7、Date to LocalDate（ 将Date 转为 LocalDate ）

public static LocalDate dateToLocalDate(Date date) {
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
    return localDateTime.toLocalDate();
}

8、LocalDate to Date

public static Date localDateToDate(LocalDate localDate) {
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDate.atStartOfDay().atZone(zone).toInstant();
    return Date.from(instant);
}

9、Date to LocalTime ( 将 Date 转为 LocalTime )

public static LocalTime dateToLocalTime(Date date) {
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
    return localDateTime.toLocalTime();
}

10、LocalTime to Date

public static Date localTimeToDate(LocalTime localTime , LocalDate localDate) {
    LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    return Date.from(instant);
}

11、获取任意日期

public static LocalDate anyDay(LocalDate localDate) {
    /**
        * 当月第一天-写法1
        */
    //第一天传入1，第二天2，第三天3，第四天4，第五天5,......
    LocalDate dayOfMonth = localDate.withDayOfMonth(2);
    /**
        * 当月第一天-写法2
        */
    LocalDate with = localDate.with(TemporalAdjusters.firstDayOfMonth());
    //当月最后一天
    LocalDate lastDate = localDate.with(TemporalAdjusters.lastDayOfMonth());
    //下一天
    LocalDate plusDays = dayOfMonth.plusDays(1);
    //前一天
    LocalDate minusDays = dayOfMonth.minusDays(1);
    // 取2014年1月第一个周一
    LocalDate firstMondayOf2014 = LocalDate.parse("2014-01-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
    return dayOfMonth;
}