Java8日期/時間

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Java8日期/時間

這篇介紹在Java8時間/日期轉換的方法。
1.以Java 8新的time package為基礎做轉換，效能較佳
2.採用builder設計模式跟lambda組合方式，讓程式更直覺
3.讓String、Date、Calendar、LocalDateTime的相互轉換更有彈性

DateTimeBuilder

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public class DateTimeBuilder {

	@FunctionalInterface
	public interface DateProcessor {
		ZonedDateTime process(ZonedDateTime zonedDateTime);
	}

	private final ZonedDateTime zonedDateTime;

	private List<DateProcessor> dateProcessors = null;

	public static final TemporalField FIRST_DAY_OF_WEEK = WeekFields.of(DayOfWeek.MONDAY, 1).dayOfWeek();

	private DateTimeBuilder(ZonedDateTime zonedDateTime) {
		this.zonedDateTime = zonedDateTime;
	}

	private DateTimeBuilder(LocalDateTime localDateTime) {
		this.zonedDateTime = ZonedDateTime.of(localDateTime, ZoneId.systemDefault());
	}

	private DateTimeBuilder(LocalDateTime localDateTime, ZoneId zoneId) {
		this.zonedDateTime = ZonedDateTime.of(localDateTime, zoneId);
	}

	/**
	 * 採用預設時區
	 *
	 * @return
	 */
	public static DateTimeBuilder localDateTime() {
		return new DateTimeBuilder(LocalDateTime.now());
	}
}

指定時間

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public DateTimeBuilder with(int hour, int minute, int second) {
	add((localDateTime) -> localDateTime.withHour(hour).withMinute(minute).withSecond(second));
	return this;
}

public DateTimeBuilder withHour(int value) {
	add((localDateTime) -> localDateTime.withHour(value));
	return this;
}

public DateTimeBuilder withMinute(int value) {
	add((localDateTime) -> localDateTime.withMinute(value));
	return this;
}

public DateTimeBuilder withSecond(int value) {
	add((localDateTime) -> localDateTime.withSecond(value));
	return this;
}

public DateTimeBuilder withMilliSecond(int value) {
	add((localDateTime) -> localDateTime.with(ChronoField.MILLI_OF_SECOND, value));
	return this;
}

plus時間

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public DateTimeBuilder plusYears(int value) {
	add((zonedDateTime) -> zonedDateTime.plusYears(value));
	return this;
}

public DateTimeBuilder plusMonths(int value) {
	add((zonedDateTime) -> zonedDateTime.plusMonths(value));
	return this;
}

public DateTimeBuilder plusWeeks(int value) {
	add((zonedDateTime) -> zonedDateTime.plusWeeks(value));
	return this;
}

public DateTimeBuilder plusDays(int value) {
	add((zonedDateTime) -> zonedDateTime.plusDays(value));
	return this;
}

public DateTimeBuilder plusHours(int value) {
	add((zonedDateTime) -> zonedDateTime.plus(value, ChronoUnit.HOURS));
	return this;
}

public DateTimeBuilder plusMinutes(int value) {
	add((zonedDateTime) -> zonedDateTime.plus(value, ChronoUnit.MINUTES));
	return this;
}

public DateTimeBuilder plusSeconds(int value) {
	add((zonedDateTime) -> zonedDateTime.plus(value, ChronoUnit.SECONDS));
	return this;
}

public DateTimeBuilder plusMillis(int value) {
	add((zonedDateTime) -> zonedDateTime.plus(value, ChronoUnit.MILLIS));
	return this;
}

minus時間

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public DateTimeBuilder minusYears(int value) {
	add((zonedDateTime) -> zonedDateTime.minusYears(value));
	return this;
}

public DateTimeBuilder minusMonths(int value) {
	add((zonedDateTime) -> zonedDateTime.minusMonths(value));
	return this;
}

public DateTimeBuilder minusWeeks(int value) {
	add((zonedDateTime) -> zonedDateTime.minusWeeks(value));
	return this;
}

public DateTimeBuilder minusDays(int value) {
	add((zonedDateTime) -> zonedDateTime.minusDays(value));
	return this;
}

public DateTimeBuilder minusHours(int value) {
	add((zonedDateTime) -> zonedDateTime.minus(value, ChronoUnit.HOURS));
	return this;
}

public DateTimeBuilder minusMinutes(int value) {
	add((zonedDateTime) -> zonedDateTime.minus(value, ChronoUnit.MINUTES));
	return this;
}

public DateTimeBuilder minusSeconds(int value) {
	add((zonedDateTime) -> zonedDateTime.minus(value, ChronoUnit.SECONDS));
	return this;
}

public DateTimeBuilder minusMillis(int value) {
	add((zonedDateTime) -> zonedDateTime.minus(value, ChronoUnit.MILLIS));
	return this;
}

Example

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DateTimeBuilder.localDateTime().toTimestamp();
DateTimeBuilder.localDateTime().withSecond(0).withMilliSecond(0).minusSeconds(secondsAgo).toTimestamp();
DateTimeBuilder.localDateTime().withMinTime().minusDays(dayAgo).toTimestamp();
...