Date Date and DateFormat class java source code Detailed
The definition of the Date class
public class Date
implements java.io.Serializable, Cloneable, Comparable<Date>
{
private static final BaseCalendar gcal =
CalendarSystem.getGregorianCalendar();
private static BaseCalendar jcal;
private transient long fastTime;
private transient BaseCalendar.Date cdate;
// Initialized just before the value is used. See parse().
private static int defaultCenturyStart;
private static final long serialVersionUID = 7523967970034938905L;
public Date() {
this(System.currentTimeMillis());
}
public Date(long date) {
fastTime = date;
}
public Object clone() {
Date d = null;
try {
d = (Date)super.clone();
if (cdate != null) {
d.cdate = (BaseCalendar.Date) cdate.clone();
}
} catch (CloneNotSupportedException e) {} // Won't happen
return d;
}
}No-argument constructor Date () automatically calls the internal System.currentTimeMills () to get the time stamp (long type, representatives from 1 January 1970 to now experienced a few milliseconds) when the Date object is created.
Date (long date) need to call manually incoming timestamp Date object to obtain a particular time. fastTime as a member variable of the class object is saved timestamp data for the Date class other function calls.
public long getTime() {
return getTimeImpl();
}
private final long getTimeImpl() {
if (cdate != null && !cdate.isNormalized()) {
normalize();
}
return fastTime;
}
public void setTime(long time) {
fastTime = time;
cdate = null;
}
public boolean before(Date when) {
return getMillisOf(this) < getMillisOf(when);
}
public boolean after(Date when) {
return getMillisOf(this) > getMillisOf(when);
}
public boolean equals(Object obj) {
return obj instanceof Date && getTime() == ((Date) obj).getTime();
}
static final long getMillisOf(Date date) {
if (date.cdate == null || date.cdate.isNormalized()) {
return date.fastTime;
}
BaseCalendar.Date d = (BaseCalendar.Date) date.cdate.clone();
return gcal.getTime(d);
}
public int compareTo(Date anotherDate) {
long thisTime = getMillisOf(this);
long anotherTime = getMillisOf(anotherDate);
return (thisTime<anotherTime ? -1 : (thisTime==anotherTime ? 0 : 1));
}
public int hashCode() {
long ht = this.getTime();
return (int) ht ^ (int) (ht >> 32);
}
public String toString() {
// "EEE MMM dd HH:mm:ss zzz yyyy";
BaseCalendar.Date date = normalize();
StringBuilder sb = new StringBuilder(28);
int index = date.getDayOfWeek();
if (index == BaseCalendar.SUNDAY) {
index = 8;
}
convertToAbbr(sb, wtb[index]).append(' '); // EEE
convertToAbbr(sb, wtb[date.getMonth() - 1 + 2 + 7]).append(' '); // MMM
CalendarUtils.sprintf0d(sb, date.getDayOfMonth(), 2).append(' '); // dd
CalendarUtils.sprintf0d(sb, date.getHours(), 2).append(':'); // HH
CalendarUtils.sprintf0d(sb, date.getMinutes(), 2).append(':'); // mm
CalendarUtils.sprintf0d(sb, date.getSeconds(), 2).append(' '); // ss
TimeZone zi = date.getZone();
if (zi != null) {
sb.append(zi.getDisplayName(date.isDaylightTime(), TimeZone.SHORT, Locale.US)); // zzz
} else {
sb.append("GMT");
}
sb.append(' ').append(date.getYear()); // yyyy
return sb.toString();
}
private static final StringBuilder convertToAbbr(StringBuilder sb, String name) {
sb.append(Character.toUpperCase(name.charAt(0)));
sb.append(name.charAt(1)).append(name.charAt(2));
return sb;
}
private final BaseCalendar.Date normalize() {
if (cdate == null) {
BaseCalendar cal = getCalendarSystem(fastTime);
cdate = (BaseCalendar.Date) cal.getCalendarDate(fastTime,
TimeZone.getDefaultRef());
return cdate;
}
// Normalize cdate with the TimeZone in cdate first. This is
// required for the compatible behavior.
if (!cdate.isNormalized()) {
cdate = normalize(cdate);
}
// If the default TimeZone has changed, then recalculate the
// fields with the new TimeZone.
TimeZone tz = TimeZone.getDefaultRef();
if (tz != cdate.getZone()) {
cdate.setZone(tz);
CalendarSystem cal = getCalendarSystem(cdate);
cal.getCalendarDate(fastTime, cdate);
}
return cdate;
}
// fastTime and the returned data are in sync upon return.
private final BaseCalendar.Date normalize(BaseCalendar.Date date) {
int y = date.getNormalizedYear();
int m = date.getMonth();
int d = date.getDayOfMonth();
int hh = date.getHours();
int mm = date.getMinutes();
int ss = date.getSeconds();
int ms = date.getMillis();
TimeZone tz = date.getZone();
// If the specified year can't be handled using a long value
// in milliseconds, GregorianCalendar is used for full
// compatibility with underflow and overflow. This is required
// by some JCK tests. The limits are based max year values -
// years that can be represented by max values of d, hh, mm,
// ss and ms. Also, let GregorianCalendar handle the default
// cutover year so that we don't need to worry about the
// transition here.
if (y == 1582 || y > 280000000 || y < -280000000) {
if (tz == null) {
tz = TimeZone.getTimeZone("GMT");
}
GregorianCalendar gc = new GregorianCalendar(tz);
gc.clear();
gc.set(GregorianCalendar.MILLISECOND, ms);
gc.set(y, m-1, d, hh, mm, ss);
fastTime = gc.getTimeInMillis();
BaseCalendar cal = getCalendarSystem(fastTime);
date = (BaseCalendar.Date) cal.getCalendarDate(fastTime, tz);
return date;
}
BaseCalendar cal = getCalendarSystem(y);
if (cal != getCalendarSystem(date)) {
date = (BaseCalendar.Date) cal.newCalendarDate(tz);
date.setNormalizedDate(y, m, d).setTimeOfDay(hh, mm, ss, ms);
}
// Perform the GregorianCalendar-style normalization.
fastTime = cal.getTime(date);
// In case the normalized date requires the other calendar
// system, we need to recalculate it using the other one.
BaseCalendar ncal = getCalendarSystem(fastTime);
if (ncal != cal) {
date = (BaseCalendar.Date) ncal.newCalendarDate(tz);
date.setNormalizedDate(y, m, d).setTimeOfDay(hh, mm, ss, ms);
fastTime = ncal.getTime(date);
}
return date;
}
private static final BaseCalendar getCalendarSystem(int year) {
if (year >= 1582) {
return gcal;
}
return getJulianCalendar();
}
private static final BaseCalendar getCalendarSystem(long utc) {
// Quickly check if the time stamp given by `utc' is the Epoch
// or later. If it's before 1970, we convert the cutover to
// local time to compare.
if (utc >= 0
|| utc >= GregorianCalendar.DEFAULT_GREGORIAN_CUTOVER
- TimeZone.getDefaultRef().getOffset(utc)) {
return gcal;
}
return getJulianCalendar();
}
private static final BaseCalendar getCalendarSystem(BaseCalendar.Date cdate) {
if (jcal == null) {
return gcal;
}
if (cdate.getEra() != null) {
return jcal;
}
return gcal;
}
synchronized private static final BaseCalendar getJulianCalendar() {
if (jcal == null) {
jcal = (BaseCalendar) CalendarSystem.forName("julian");
}
return jcal;
}
private void writeObject(ObjectOutputStream s)
throws IOException
{
s.writeLong(getTimeImpl());
}
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException
{
fastTime = s.readLong();
}
public static Date from(Instant instant) {
try {
return new Date(instant.toEpochMilli());
} catch (ArithmeticException ex) {
throw new IllegalArgumentException(ex);
}
}
public Instant toInstant() {
return Instant.ofEpochMilli(getTime());
}
}
Date commonly used functions
after(Date date)
This function is used to compare datewhether the incoming parameters than whenlater in time, if later it returns true, otherwise it returns false. Wherein the getMillisOfmethod is used to obtain a Datetimestamp object storage time.
before(Date date)
Meaning above and after()vice versa
compareTo(Date date)
This approach is in order sort(sort) services, compareTothree ways to return value (-1, 0) meaning not repeat them here. This method is by comparing the two datedetermined from the number of milliseconds of the target time 1970.1.1 who whose large small.
getTime()
In fact, return to save the Datemember variables timestamp of the object fastTime(the dateobject is the number of milliseconds from the time of 1970.1.1).
Annotated Java class library contains two classes, one is used to indicate the point in time of the Date class, and the other is used to indicate a familiar calendar notation LocalDate class.
Separating the calendar time is a good object-oriented design, is usually best to use different classes represent different concepts.
public final class LocalDate
implements Temporal, TemporalAdjuster, ChronoLocalDate, Serializable {
/**
* 最小的LocalDate日期 '-999999999-01-01'.
* 表示过去很久
*/
public static final LocalDate MIN = LocalDate.of(Year.MIN_VALUE, 1, 1);
/**
* 最大的LocalDate日期'+999999999-12-31'
* 表示很久以后
*/
public static final LocalDate MAX = LocalDate.of(Year.MAX_VALUE, 12, 31);
/**
* Serialization version.
*/
private static final long serialVersionUID = 2942565459149668126L;
/**
* 400年是一个循环 共146097天
*/
private static final int DAYS_PER_CYCLE = 146097;
/**
* 计算0000-1970年共多少天，这里倒过来算即先算2000年的再回退30年
*/
static final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
/**
* The year.
*/
private final int year;
/**
* The month-of-year.
*/
private final short month;
/**
* The day-of-month.
*/
private final short day;
//-----------------------------------------------------------------------
/**
* 获取本地系统时钟的时区
*/
public static LocalDate now() {
return now(Clock.systemDefaultZone());
}
/**
* 使用特定时区
*/
public static LocalDate now(ZoneId zone) {
return now(Clock.system(zone));
}
/**
* 获取当前日期，传入参数clock
*/
public static LocalDate now(Clock clock) {
Objects.requireNonNull(clock, "clock");
// inline to avoid creating object and Instant checks
final Instant now = clock.instant(); // called once
ZoneOffset offset = clock.getZone().getRules().getOffset(now);
long epochSec = now.getEpochSecond() + offset.getTotalSeconds(); // overflow caught later
long epochDay = Math.floorDiv(epochSec, SECONDS_PER_DAY);
return LocalDate.ofEpochDay(epochDay);
}
//-----------------------------------------------------------------------
/**
*用特定的年月日返回LocalDate,这里月份是Month类型，也就是英文的JUNE,MAY那些
*/
public static LocalDate of(int year, Month month, int dayOfMonth) {
YEAR.checkValidValue(year);
Objects.requireNonNull(month, "month");
DAY_OF_MONTH.checkValidValue(dayOfMonth);
return create(year, month.getValue(), dayOfMonth);
}
/**
*用特定的年月日返回LocalDate
*/
public static LocalDate of(int year, int month, int dayOfMonth) {
YEAR.checkValidValue(year);
MONTH_OF_YEAR.checkValidValue(month);
DAY_OF_MONTH.checkValidValue(dayOfMonth);
return create(year, month, dayOfMonth);
}
//-----------------------------------------------------------------------
/**
*用年和一年中的第几天来返回LocalDate
*/
public static LocalDate ofYearDay(int year, int dayOfYear) {
YEAR.checkValidValue(year);
DAY_OF_YEAR.checkValidValue(dayOfYear);
boolean leap = IsoChronology.INSTANCE.isLeapYear(year);
if (dayOfYear == 366 && leap == false) {
throw new DateTimeException("Invalid date 'DayOfYear 366' as '" + year + "' is not a leap year");
}
Month moy = Month.of((dayOfYear - 1) / 31 + 1);
int monthEnd = moy.firstDayOfYear(leap) + moy.length(leap) - 1;
if (dayOfYear > monthEnd) {
moy = moy.plus(1);
}
int dom = dayOfYear - moy.firstDayOfYear(leap) + 1;
return new LocalDate(year, moy.getValue(), dom);
}
//-----------------------------------------------------------------------
/**
* 用纪元时间来返回LocalDate。就是从1970-01-01
*/
public static LocalDate ofEpochDay(long epochDay) {
long zeroDay = epochDay + DAYS_0000_TO_1970;
// find the march-based year
zeroDay -= 60; // adjust to 0000-03-01 so leap day is at end of four year cycle
long adjust = 0;
if (zeroDay < 0) {
// adjust negative years to positive for calculation
long adjustCycles = (zeroDay + 1) / DAYS_PER_CYCLE - 1;
adjust = adjustCycles * 400;
zeroDay += -adjustCycles * DAYS_PER_CYCLE;
}
long yearEst = (400 * zeroDay + 591) / DAYS_PER_CYCLE;
long doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
if (doyEst < 0) {
// fix estimate
yearEst--;
doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
}
yearEst += adjust; // reset any negative year
int marchDoy0 = (int) doyEst;
// convert march-based values back to january-based
int marchMonth0 = (marchDoy0 * 5 + 2) / 153;
int month = (marchMonth0 + 2) % 12 + 1;
int dom = marchDoy0 - (marchMonth0 * 306 + 5) / 10 + 1;
yearEst += marchMonth0 / 10;
// check year now we are certain it is correct
int year = YEAR.checkValidIntValue(yearEst);
return new LocalDate(year, month, dom);
}
//-----------------------------------------------------------------------
/**
*
*/
public static LocalDate from(TemporalAccessor temporal) {
Objects.requireNonNull(temporal, "temporal");
LocalDate date = temporal.query(TemporalQueries.localDate());
if (date == null) {
throw new DateTimeException("Unable to obtain LocalDate from TemporalAccessor: " +
temporal + " of type " + temporal.getClass().getName());
}
return date;
}
//-----------------------------------------------------------------------
/**
* 解析像 {@code 2007-12-03} 格式的为LocalDate.实际底层封装了DateTimeFormatter.ISO_LOCAL_DATE格式也就是2007-12-03这种
*/
public static LocalDate parse(CharSequence text) {
return parse(text, DateTimeFormatter.ISO_LOCAL_DATE);
}
/**
* 传入一直预定义的DateTimeFormatter格式，进行解析返回LocalDate.可查看相关
*/
public static LocalDate parse(CharSequence text, DateTimeFormatter formatter) {
Objects.requireNonNull(formatter, "formatter");
return formatter.parse(text, LocalDate::from);
}
//-----------------------------------------------------------------------
/**
*私有方法返回传入年月日参数的LocalDate
*/
private static LocalDate create(int year, int month, int dayOfMonth) {
if (dayOfMonth > 28) {
int dom = 31;
switch (month) {
case 2:
dom = (IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
break;
case 4:
case 6:
case 9:
case 11:
dom = 30;
break;
}
if (dayOfMonth > dom) {
if (dayOfMonth == 29) {
throw new DateTimeException("Invalid date 'February 29' as '" + year + "' is not a leap year");
} else {
throw new DateTimeException("Invalid date '" + Month.of(month).name() + " " + dayOfMonth + "'");
}
}
}
return new LocalDate(year, month, dayOfMonth);
}
/**
* 判断传递的日期是否合理
*/
private static LocalDate resolvePreviousValid(int year, int month, int day) {
switch (month) {
case 2:
day = Math.min(day, IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
break;
case 4:
case 6:
case 9:
case 11:
day = Math.min(day, 30);
break;
}
return new LocalDate(year, month, day);
}
/**
* 私有的构造函数
*/
private LocalDate(int year, int month, int dayOfMonth) {
this.year = year;
this.month = (short) month;
this.day = (short) dayOfMonth;
}
//-----------------------------------------------------------------------
/**
* 检查特定的变量是否被支持，以下是支持的种类：
* <ul>
* <li>{@code DAY_OF_WEEK}
* <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
* <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR}
* <li>{@code DAY_OF_MONTH}
* <li>{@code DAY_OF_YEAR}
* <li>{@code EPOCH_DAY}
* <li>{@code ALIGNED_WEEK_OF_MONTH}
* <li>{@code ALIGNED_WEEK_OF_YEAR}
* <li>{@code MONTH_OF_YEAR}
* <li>{@code PROLEPTIC_MONTH}
* <li>{@code YEAR_OF_ERA}
* <li>{@code YEAR}
* <li>{@code ERA}
* </ul>
*对于非以上种类返回false
*/
@Override // override for Javadoc
public boolean isSupported(TemporalField field) {
return ChronoLocalDate.super.isSupported(field);
}
/**
* 检查特定的unit是否支持，如果不支持在进行plus，minus方法时会抛出异常
* 支持的单元有：
* <ul>
* <li>{@code DAYS}
* <li>{@code WEEKS}
* <li>{@code MONTHS}
* <li>{@code YEARS}
* <li>{@code DECADES}
* <li>{@code CENTURIES}
* <li>{@code MILLENNIA}
* <li>{@code ERAS}
* </ul>
* 其他类型会返回false
*/
@Override // override for Javadoc
public boolean isSupported(TemporalUnit unit) {
return ChronoLocalDate.super.isSupported(unit);
}
//-----------------------------------------------------------------------
/**
* 获取特定变量的合法值
*/
@Override
public ValueRange range(TemporalField field) {
if (field instanceof ChronoField) {
ChronoField f = (ChronoField) field;
if (f.isDateBased()) {
switch (f) {
case DAY_OF_MONTH: return ValueRange.of(1, lengthOfMonth());
case DAY_OF_YEAR: return ValueRange.of(1, lengthOfYear());
case ALIGNED_WEEK_OF_MONTH: return ValueRange.of(1, getMonth() == Month.FEBRUARY && isLeapYear() == false ? 4 : 5);
case YEAR_OF_ERA:
return (getYear() <= 0 ? ValueRange.of(1, Year.MAX_VALUE + 1) : ValueRange.of(1, Year.MAX_VALUE));
}
return field.range();
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.rangeRefinedBy(this);
}
/**
* 从特定的变量中取值返回int类型
*/
@Override // override for Javadoc and performance
public int get(TemporalField field) {
if (field instanceof ChronoField) {
return get0(field);
}
return ChronoLocalDate.super.get(field);
}
/**
* 从特定的变量中取值返回long类型
*/
@Override
public long getLong(TemporalField field) {
if (field instanceof ChronoField) {
if (field == EPOCH_DAY) {
return toEpochDay();
}
if (field == PROLEPTIC_MONTH) {
return getProlepticMonth();
}
return get0(field);
}
return field.getFrom(this);
}
private int get0(TemporalField field) {
switch ((ChronoField) field) {
case DAY_OF_WEEK: return getDayOfWeek().getValue();
case ALIGNED_DAY_OF_WEEK_IN_MONTH: return ((day - 1) % 7) + 1;
case ALIGNED_DAY_OF_WEEK_IN_YEAR: return ((getDayOfYear() - 1) % 7) + 1;
case DAY_OF_MONTH: return day;
case DAY_OF_YEAR: return getDayOfYear();
case EPOCH_DAY: throw new UnsupportedTemporalTypeException("Invalid field 'EpochDay' for get() method, use getLong() instead");
case ALIGNED_WEEK_OF_MONTH: return ((day - 1) / 7) + 1;
case ALIGNED_WEEK_OF_YEAR: return ((getDayOfYear() - 1) / 7) + 1;
case MONTH_OF_YEAR: return month;
case PROLEPTIC_MONTH: throw new UnsupportedTemporalTypeException("Invalid field 'ProlepticMonth' for get() method, use getLong() instead");
case YEAR_OF_ERA: return (year >= 1 ? year : 1 - year);
case YEAR: return year;
case ERA: return (year >= 1 ? 1 : 0);
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
private long getProlepticMonth() {
return (year * 12L + month - 1);
}
//-----------------------------------------------------------------------
/**
* 获取数据的年表，ISO日历系统标准
*/
@Override
public IsoChronology getChronology() {
return IsoChronology.INSTANCE;
}
/**
* 获取时间的era，像BE.AD这些（公元，公元前...）
*/
@Override // override for Javadoc
public Era getEra() {
return ChronoLocalDate.super.getEra();
}
/**
* 获取年
*/
public int getYear() {
return year;
}
/**
* 获取月份
*/
public int getMonthValue() {
return month;
}
/**
* 获取英文的那种月份
*/
public Month getMonth() {
return Month.of(month);
}
/**
* 获取日
*/
public int getDayOfMonth() {
return day;
}
/**
* 获取一年中的第几天
*/
public int getDayOfYear() {
return getMonth().firstDayOfYear(isLeapYear()) + day - 1;
}
/**
* 获取1周中的第几天
*/
public DayOfWeek getDayOfWeek() {
int dow0 = (int)Math.floorMod(toEpochDay() + 3, 7);
return DayOfWeek.of(dow0 + 1);
}
//-----------------------------------------------------------------------
/**
* 判断是否是闰年
*/
@Override // override for Javadoc and performance
public boolean isLeapYear() {
return IsoChronology.INSTANCE.isLeapYear(year);
}
/**
* 返回月份的长度
*/
@Override
public int lengthOfMonth() {
switch (month) {
case 2:
return (isLeapYear() ? 29 : 28);
case 4:
case 6:
case 9:
case 11:
return 30;
default:
return 31;
}
}
/**
* 返回年的长度
public int lengthOfYear() {
return (isLeapYear() ? 366 : 365);
}
//-----------------------------------------------------------------------
/**
* 返回一个调整过的LocalDate类型，这些adjuster是预定义的
*/
@Override
public LocalDate with(TemporalAdjuster adjuster) {
// optimizations
if (adjuster instanceof LocalDate) {
return (LocalDate) adjuster;
}
return (LocalDate) adjuster.adjustInto(this);
}
/**
* 返回一个调整过的LocalDate类型，这些adjuster是预定义的，传入一个新的值
*/
@Override
public LocalDate with(TemporalField field, long newValue) {
if (field instanceof ChronoField) {
ChronoField f = (ChronoField) field;
f.checkValidValue(newValue);
switch (f) {
case DAY_OF_WEEK: return plusDays(newValue - getDayOfWeek().getValue());
case ALIGNED_DAY_OF_WEEK_IN_MONTH: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_MONTH));
case ALIGNED_DAY_OF_WEEK_IN_YEAR: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_YEAR));
case DAY_OF_MONTH: return withDayOfMonth((int) newValue);
case DAY_OF_YEAR: return withDayOfYear((int) newValue);
case EPOCH_DAY: return LocalDate.ofEpochDay(newValue);
case ALIGNED_WEEK_OF_MONTH: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_MONTH));
case ALIGNED_WEEK_OF_YEAR: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_YEAR));
case MONTH_OF_YEAR: return withMonth((int) newValue);
case PROLEPTIC_MONTH: return plusMonths(newValue - getProlepticMonth());
case YEAR_OF_ERA: return withYear((int) (year >= 1 ? newValue : 1 - newValue));
case YEAR: return withYear((int) newValue);
case ERA: return (getLong(ERA) == newValue ? this : withYear(1 - year));
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.adjustInto(this, newValue);
}
//-----------------------------------------------------------------------
/**
* 改年返回新的LocalDate
*/
public LocalDate withYear(int year) {
if (this.year == year) {
return this;
}
YEAR.checkValidValue(year);
return resolvePreviousValid(year, month, day);
}
/**
* 改月返回新的LocalDate
*/
public LocalDate withMonth(int month) {
if (this.month == month) {
return this;
}
MONTH_OF_YEAR.checkValidValue(month);
return resolvePreviousValid(year, month, day);
}
/**
*改日返回新的LocalDate
*/
public LocalDate withDayOfMonth(int dayOfMonth) {
if (this.day == dayOfMonth) {
return this;
}
return of(year, month, dayOfMonth);
}
/**
* 改一年中第几日返回新的LocalDate
*/
public LocalDate withDayOfYear(int dayOfYear) {
if (this.getDayOfYear() == dayOfYear) {
return this;
}
return ofYearDay(year, dayOfYear);
}
//-----------------------------------------------------------------------
/**
* 返回新的LocalDate，在原值上进行 加 操作
*/
@Override
public LocalDate plus(TemporalAmount amountToAdd) {
if (amountToAdd instanceof Period) {
Period periodToAdd = (Period) amountToAdd;
return plusMonths(periodToAdd.toTotalMonths()).plusDays(periodToAdd.getDays());
}
Objects.requireNonNull(amountToAdd, "amountToAdd");
return (LocalDate) amountToAdd.addTo(this);
}
/**
* 返回新的LocalDate，在原值上进行 加 操作
/
@Override
public LocalDate plus(long amountToAdd, TemporalUnit unit) {
if (unit instanceof ChronoUnit) {
ChronoUnit f = (ChronoUnit) unit;
switch (f) {
case DAYS: return plusDays(amountToAdd);
case WEEKS: return plusWeeks(amountToAdd);
case MONTHS: return plusMonths(amountToAdd);
case YEARS: return plusYears(amountToAdd);
case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
}
throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
}
return unit.addTo(this, amountToAdd);
}
//-----------------------------------------------------------------------
/**
* 在原本基础上对年添加传入值后返回一个LocalDate
*/
public LocalDate plusYears(long yearsToAdd) {
if (yearsToAdd == 0) {
return this;
}
int newYear = YEAR.checkValidIntValue(year + yearsToAdd); // safe overflow
return resolvePreviousValid(newYear, month, day);
}
/**
* 在原本基础上对月添加传入值后返回一个LocalDate
*/
public LocalDate plusMonths(long monthsToAdd) {
if (monthsToAdd == 0) {
return this;
}
long monthCount = year * 12L + (month - 1);
long calcMonths = monthCount + monthsToAdd; // safe overflow
int newYear = YEAR.checkValidIntValue(Math.floorDiv(calcMonths, 12));
int newMonth = (int)Math.floorMod(calcMonths, 12) + 1;
return resolvePreviousValid(newYear, newMonth, day);
}
/**
* 在原本基础上对周添加传入值后返回一个LocalDate，底层调用的是加7天
*/
public LocalDate plusWeeks(long weeksToAdd) {
return plusDays(Math.multiplyExact(weeksToAdd, 7));
}
/**
* 在原本基础上对日添加传入值后返回一个LocalDate
*/
public LocalDate plusDays(long daysToAdd) {
if (daysToAdd == 0) {
return this;
}
long mjDay = Math.addExact(toEpochDay(), daysToAdd);
return LocalDate.ofEpochDay(mjDay);
}
//-----------------------------------------------------------------------
/**
* 减，底层调用的还是plus相关的方法，传入的是实际上是负值
*/
@Override
public LocalDate minus(TemporalAmount amountToSubtract) {
if (amountToSubtract instanceof Period) {
Period periodToSubtract = (Period) amountToSubtract;
return minusMonths(periodToSubtract.toTotalMonths()).minusDays(periodToSubtract.getDays());
}
Objects.requireNonNull(amountToSubtract, "amountToSubtract");
return (LocalDate) amountToSubtract.subtractFrom(this);
}
@Override
public LocalDate minus(long amountToSubtract, TemporalUnit unit) {
return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
}
public LocalDate minusYears(long yearsToSubtract) {
return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
}
public LocalDate minusMonths(long monthsToSubtract) {
return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
}
public LocalDate minusWeeks(long weeksToSubtract) {
return (weeksToSubtract == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeksToSubtract));
}
public LocalDate minusDays(long daysToSubtract) {
return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
}
//-----------------------------------------------------------------------
/**
* 特定查询
*/
@SuppressWarnings("unchecked")
@Override
public <R> R query(TemporalQuery<R> query) {
if (query == TemporalQueries.localDate()) {
return (R) this;
}
return ChronoLocalDate.super.query(query);
}
/**
*
* <pre>
* // 下面两种是相同的，但推荐第二种
* temporal = thisLocalDate.adjustInto(temporal);
* temporal = temporal.with(thisLocalDate);
* </pre>
*
*/
@Override // override for Javadoc
public Temporal adjustInto(Temporal temporal) {
return ChronoLocalDate.super.adjustInto(temporal);
}
@Override
public long until(Temporal endExclusive, TemporalUnit unit) {
LocalDate end = LocalDate.from(endExclusive);
if (unit instanceof ChronoUnit) {
switch ((ChronoUnit) unit) {
case DAYS: return daysUntil(end);
case WEEKS: return daysUntil(end) / 7;
case MONTHS: return monthsUntil(end);
case YEARS: return monthsUntil(end) / 12;
case DECADES: return monthsUntil(end) / 120;
case CENTURIES: return monthsUntil(end) / 1200;
case MILLENNIA: return monthsUntil(end) / 12000;
case ERAS: return end.getLong(ERA) - getLong(ERA);
}
throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
}
return unit.between(this, end);
}
long daysUntil(LocalDate end) {
return end.toEpochDay() - toEpochDay(); // no overflow
}
private long monthsUntil(LocalDate end) {
long packed1 = getProlepticMonth() * 32L + getDayOfMonth(); // no overflow
long packed2 = end.getProlepticMonth() * 32L + end.getDayOfMonth(); // no overflow
return (packed2 - packed1) / 32;
}
@Override
public Period until(ChronoLocalDate endDateExclusive) {
LocalDate end = LocalDate.from(endDateExclusive);
long totalMonths = end.getProlepticMonth() - this.getProlepticMonth(); // safe
int days = end.day - this.day;
if (totalMonths > 0 && days < 0) {
totalMonths--;
LocalDate calcDate = this.plusMonths(totalMonths);
days = (int) (end.toEpochDay() - calcDate.toEpochDay()); // safe
} else if (totalMonths < 0 && days > 0) {
totalMonths++;
days -= end.lengthOfMonth();
}
long years = totalMonths / 12; // safe
int months = (int) (totalMonths % 12); // safe
return Period.of(Math.toIntExact(years), months, days);
}
/**
* 用特定的格式格式化日期
*/
@Override // override for Javadoc and performance
public String format(DateTimeFormatter formatter) {
Objects.requireNonNull(formatter, "formatter");
return formatter.format(this);
}
//-----------------------------------------------------------------------
/**
* 结合时间格式LocalTime，返回一个LocalDateTime对象
*/
@Override
public LocalDateTime atTime(LocalTime time) {
return LocalDateTime.of(this, time);
}
/**
* 结合时间格式： 时 分，返回一个LocalDateTime对象
*/
public LocalDateTime atTime(int hour, int minute) {
return atTime(LocalTime.of(hour, minute));
}
/**
* 结合时分秒，返回一个LocalDateTime对象
*/
public LocalDateTime atTime(int hour, int minute, int second) {
return atTime(LocalTime.of(hour, minute, second));
}
/**
* 结合时分秒 纳秒，返回一个LocalDateTime对象
*/
public LocalDateTime atTime(int hour, int minute, int second, int nanoOfSecond) {
return atTime(LocalTime.of(hour, minute, second, nanoOfSecond));
}
/**
* 结合一个OffsetTime格式，返回一个OffsetTime对象。OffsetTime表示具有相对于UTC的固定区偏移的时间。
*/
public OffsetDateTime atTime(OffsetTime time) {
return OffsetDateTime.of(LocalDateTime.of(this, time.toLocalTime()), time.getOffset());
}
/**
* 结合午夜时间0点返回一个LocalDateTime对象
*/
public LocalDateTime atStartOfDay() {
return LocalDateTime.of(this, LocalTime.MIDNIGHT);
}
/**
* 传入时区id，返回一个ZonedDateTime
*/
public ZonedDateTime atStartOfDay(ZoneId zone) {
Objects.requireNonNull(zone, "zone");
// need to handle case where there is a gap from 11:30 to 00:30
// standard ZDT factory would result in 01:00 rather than 00:30
LocalDateTime ldt = atTime(LocalTime.MIDNIGHT);
if (zone instanceof ZoneOffset == false) {
ZoneRules rules = zone.getRules();
ZoneOffsetTransition trans = rules.getTransition(ldt);
if (trans != null && trans.isGap()) {
ldt = trans.getDateTimeAfter();
}
}
return ZonedDateTime.of(ldt, zone);
}
//-----------------------------------------------------------------------
@Override
public long toEpochDay() {
long y = year;
long m = month;
long total = 0;
total += 365 * y;
if (y >= 0) {
total += (y + 3) / 4 - (y + 99) / 100 + (y + 399) / 400;
} else {
total -= y / -4 - y / -100 + y / -400;
}
total += ((367 * m - 362) / 12);
total += day - 1;
if (m > 2) {
total--;
if (isLeapYear() == false) {
total--;
}
}
return total - DAYS_0000_TO_1970;
}
//-----------------------------------------------------------------------
/**
* 和另一个日期的年月日进行比较判断
*/
@Override // override for Javadoc and performance
public int compareTo(ChronoLocalDate other) {
if (other instanceof LocalDate) {
return compareTo0((LocalDate) other);
}
return ChronoLocalDate.super.compareTo(other);
}
int compareTo0(LocalDate otherDate) {
int cmp = (year - otherDate.year);
if (cmp == 0) {
cmp = (month - otherDate.month);
if (cmp == 0) {
cmp = (day - otherDate.day);
}
}
return cmp;
}
/**
* 判断一个日期是否在另一个之后
*/
@Override // override for Javadoc and performance
public boolean isAfter(ChronoLocalDate other) {
if (other instanceof LocalDate) {
return compareTo0((LocalDate) other) > 0;
}
return ChronoLocalDate.super.isAfter(other);
}
/**
* 判断一个日期是否在另一个日期之前
*/
@Override // override for Javadoc and performance
public boolean isBefore(ChronoLocalDate other) {
if (other instanceof LocalDate) {
return compareTo0((LocalDate) other) < 0;
}
return ChronoLocalDate.super.isBefore(other);
}
/**
* 判断一个日期是否在另一个之前
*/
@Override // override for Javadoc and performance
public boolean isEqual(ChronoLocalDate other) {
if (other instanceof LocalDate) {
return compareTo0((LocalDate) other) == 0;
}
return ChronoLocalDate.super.isEqual(other);
}
//-----------------------------------------------------------------------
/**
* 重写object的equals方法，判断与对象obj是否相等
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof LocalDate) {
return compareTo0((LocalDate) obj) == 0;
}
return false;
}
/**
* 重写object的hashcode方法
*/
@Override
public int hashCode() {
int yearValue = year;
int monthValue = month;
int dayValue = day;
return (yearValue & 0xFFFFF800) ^ ((yearValue << 11) + (monthValue << 6) + (dayValue));
}
//-----------------------------------------------------------------------
/**
*重写toString方法，返回格式： {@code 2007-12-03}.
*
*/
@Override
public String toString() {
int yearValue = year;
int monthValue = month;
int dayValue = day;
int absYear = Math.abs(yearValue);
StringBuilder buf = new StringBuilder(10);
if (absYear < 1000) {
if (yearValue < 0) {
buf.append(yearValue - 10000).deleteCharAt(1);
} else {
buf.append(yearValue + 10000).deleteCharAt(0);
}
} else {
if (yearValue > 9999) {
buf.append('+');
}
buf.append(yearValue);
}
return buf.append(monthValue < 10 ? "-0" : "-")
.append(monthValue)
.append(dayValue < 10 ? "-0" : "-")
.append(dayValue)
.toString();
}
private Object writeReplace() {
return new Ser(Ser.LOCAL_DATE_TYPE, this);
}
private void readObject(ObjectInputStream s) throws InvalidObjectException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
void writeExternal(DataOutput out) throws IOException {
out.writeInt(year);
out.writeByte(month);
out.writeByte(day);
}
static LocalDate readExternal(DataInput in) throws IOException {
int year = in.readInt();
int month = in.readByte();
int dayOfMonth = in.readByte();
return LocalDate.of(year, month, dayOfMonth);
}
}
原文链接：https://blog.csdn.net/sayWhat_sayHello/article/details/80418498Do not use the constructor to construct an object LocalDate class. In fact, you should use the static factory method on behalf of the constructor call
LocalDate.now();
The date may be provided to construct objects of a particular date, LocalDate newYearValue = LocalDate.of (1999,12,31)
Once you have LocalDate object, you can use getYear, getMonthValue, getDayOfMonth get date.
newYearValue .plusDays (1000) will get a new target date, a specified number of days from the current date of the new date.
Displays the current month's calendar
