Back to index...

	/*
	* Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.nio.file.attribute;

	import java.time.Instant;
	import java.time.LocalDateTime;
	import java.time.ZoneOffset;
	import java.util.Objects;
	import java.util.concurrent.TimeUnit;

	/**
	* Represents the value of a file's time stamp attribute. For example, it may
	* represent the time that the file was last
	* {@link BasicFileAttributes#lastModifiedTime() modified},
	* {@link BasicFileAttributes#lastAccessTime() accessed},
	* or {@link BasicFileAttributes#creationTime() created}.
	*
	* <p> Instances of this class are immutable.
	*
	* @since 1.7
	* @see java.nio.file.Files#setLastModifiedTime
	* @see java.nio.file.Files#getLastModifiedTime
	*/

	public final class FileTime
	implements Comparable<FileTime>
	{
	/**
	* The unit of granularity to interpret the value. Null if
	* this {@code FileTime} is converted from an {@code Instant},
	* the {@code value} and {@code unit} pair will not be used
	* in this scenario.
	*/
	private final TimeUnit unit;

	/**
	* The value since the epoch; can be negative.
	*/
	private final long value;

	/**
	* The value as Instant (created lazily, if not from an instant)
	*/
	private Instant instant;

	/**
	* The value return by toString (created lazily)
	*/
	private String valueAsString;

	/**
	* Initializes a new instance of this class.
	*/
	private FileTime(long value, TimeUnit unit, Instant instant) {
	this.value = value;
	this.unit = unit;
	this.instant = instant;
	}

	/**
	* Returns a {@code FileTime} representing a value at the given unit of
	* granularity.
	*
	* @param value
	* the value since the epoch (1970-01-01T00:00:00Z); can be
	* negative
	* @param unit
	* the unit of granularity to interpret the value
	*
	* @return a {@code FileTime} representing the given value
	*/
	public static FileTime from(long value, TimeUnit unit) {
	Objects.requireNonNull(unit, "unit");
	return new FileTime(value, unit, null);
	}

	/**
	* Returns a {@code FileTime} representing the given value in milliseconds.
	*
	* @param value
	* the value, in milliseconds, since the epoch
	* (1970-01-01T00:00:00Z); can be negative
	*
	* @return a {@code FileTime} representing the given value
	*/
	public static FileTime fromMillis(long value) {
	return new FileTime(value, TimeUnit.MILLISECONDS, null);
	}

	/**
	* Returns a {@code FileTime} representing the same point of time value
	* on the time-line as the provided {@code Instant} object.
	*
	* @param instant
	* the instant to convert
	* @return a {@code FileTime} representing the same point on the time-line
	* as the provided instant
	* @since 1.8
	*/
	public static FileTime from(Instant instant) {
	Objects.requireNonNull(instant, "instant");
	return new FileTime(0, null, instant);
	}

	/**
	* Returns the value at the given unit of granularity.
	*
	* <p> Conversion from a coarser granularity that would numerically overflow
	* saturate to {@code Long.MIN_VALUE} if negative or {@code Long.MAX_VALUE}
	* if positive.
	*
	* @param unit
	* the unit of granularity for the return value
	*
	* @return value in the given unit of granularity, since the epoch
	* since the epoch (1970-01-01T00:00:00Z); can be negative
	*/
	public long to(TimeUnit unit) {
	Objects.requireNonNull(unit, "unit");
	if (this.unit != null) {
	return unit.convert(this.value, this.unit);
	} else {
	long secs = unit.convert(instant.getEpochSecond(), TimeUnit.SECONDS);
	if (secs == Long.MIN_VALUE \|\| secs == Long.MAX_VALUE) {
	return secs;
	}
	long nanos = unit.convert(instant.getNano(), TimeUnit.NANOSECONDS);
	long r = secs + nanos;
	// Math.addExact() variant
	if (((secs ^ r) & (nanos ^ r)) < 0) {
	return (secs < 0) ? Long.MIN_VALUE : Long.MAX_VALUE;
	}
	return r;
	}
	}

	/**
	* Returns the value in milliseconds.
	*
	* <p> Conversion from a coarser granularity that would numerically overflow
	* saturate to {@code Long.MIN_VALUE} if negative or {@code Long.MAX_VALUE}
	* if positive.
	*
	* @return the value in milliseconds, since the epoch (1970-01-01T00:00:00Z)
	*/
	public long toMillis() {
	if (unit != null) {
	return unit.toMillis(value);
	} else {
	long secs = instant.getEpochSecond();
	int nanos = instant.getNano();
	// Math.multiplyExact() variant
	long r = secs * 1000;
	long ax = Math.abs(secs);
	if (((ax \| 1000) >>> 31 != 0)) {
	if ((r / 1000) != secs) {
	return (secs < 0) ? Long.MIN_VALUE : Long.MAX_VALUE;
	}
	}
	return r + nanos / 1000_000;
	}
	}

	/**
	* Time unit constants for conversion.
	*/
	private static final long HOURS_PER_DAY = 24L;
	private static final long MINUTES_PER_HOUR = 60L;
	private static final long SECONDS_PER_MINUTE = 60L;
	private static final long SECONDS_PER_HOUR = SECONDS_PER_MINUTE * MINUTES_PER_HOUR;
	private static final long SECONDS_PER_DAY = SECONDS_PER_HOUR * HOURS_PER_DAY;
	private static final long MILLIS_PER_SECOND = 1000L;
	private static final long MICROS_PER_SECOND = 1000_000L;
	private static final long NANOS_PER_SECOND = 1000_000_000L;
	private static final int NANOS_PER_MILLI = 1000_000;
	private static final int NANOS_PER_MICRO = 1000;
	// The epoch second of Instant.MIN.
	private static final long MIN_SECOND = -31557014167219200L;
	// The epoch second of Instant.MAX.
	private static final long MAX_SECOND = 31556889864403199L;

	/*
	* Scale d by m, checking for overflow.
	*/
	private static long scale(long d, long m, long over) {
	if (d > over) return Long.MAX_VALUE;
	if (d < -over) return Long.MIN_VALUE;
	return d * m;
	}

	/**
	* Converts this {@code FileTime} object to an {@code Instant}.
	*
	* <p> The conversion creates an {@code Instant} that represents the
	* same point on the time-line as this {@code FileTime}.
	*
	* <p> {@code FileTime} can store points on the time-line further in the
	* future and further in the past than {@code Instant}. Conversion
	* from such further time points saturates to {@link Instant#MIN} if
	* earlier than {@code Instant.MIN} or {@link Instant#MAX} if later
	* than {@code Instant.MAX}.
	*
	* @return an instant representing the same point on the time-line as
	* this {@code FileTime} object
	* @since 1.8
	*/
	public Instant toInstant() {
	if (instant == null) {
	long secs = 0L;
	int nanos = 0;
	switch (unit) {
	case DAYS:
	secs = scale(value, SECONDS_PER_DAY,
	Long.MAX_VALUE/SECONDS_PER_DAY);
	break;
	case HOURS:
	secs = scale(value, SECONDS_PER_HOUR,
	Long.MAX_VALUE/SECONDS_PER_HOUR);
	break;
	case MINUTES:
	secs = scale(value, SECONDS_PER_MINUTE,
	Long.MAX_VALUE/SECONDS_PER_MINUTE);
	break;
	case SECONDS:
	secs = value;
	break;
	case MILLISECONDS:
	secs = Math.floorDiv(value, MILLIS_PER_SECOND);
	nanos = (int)Math.floorMod(value, MILLIS_PER_SECOND)
	* NANOS_PER_MILLI;
	break;
	case MICROSECONDS:
	secs = Math.floorDiv(value, MICROS_PER_SECOND);
	nanos = (int)Math.floorMod(value, MICROS_PER_SECOND)
	* NANOS_PER_MICRO;
	break;
	case NANOSECONDS:
	secs = Math.floorDiv(value, NANOS_PER_SECOND);
	nanos = (int)Math.floorMod(value, NANOS_PER_SECOND);
	break;
	default : throw new AssertionError("Unit not handled");
	}
	if (secs <= MIN_SECOND)
	instant = Instant.MIN;
	else if (secs >= MAX_SECOND)
	instant = Instant.MAX;
	else
	instant = Instant.ofEpochSecond(secs, nanos);
	}
	return instant;
	}

	/**
	* Tests this {@code FileTime} for equality with the given object.
	*
	* <p> The result is {@code true} if and only if the argument is not {@code
	* null} and is a {@code FileTime} that represents the same time. This
	* method satisfies the general contract of the {@code Object.equals} method.
	*
	* @param obj
	* the object to compare with
	*
	* @return {@code true} if, and only if, the given object is a {@code
	* FileTime} that represents the same time
	*/
	@Override
	public boolean equals(Object obj) {
	return (obj instanceof FileTime) ? compareTo((FileTime)obj) == 0 : false;
	}

	/**
	* Computes a hash code for this file time.
	*
	* <p> The hash code is based upon the value represented, and satisfies the
	* general contract of the {@link Object#hashCode} method.
	*
	* @return the hash-code value
	*/
	@Override
	public int hashCode() {
	// hashcode of instant representation to satisfy contract with equals
	return toInstant().hashCode();
	}

	private long toDays() {
	if (unit != null) {
	return unit.toDays(value);
	} else {
	return TimeUnit.SECONDS.toDays(toInstant().getEpochSecond());
	}
	}

	private long toExcessNanos(long days) {
	if (unit != null) {
	return unit.toNanos(value - unit.convert(days, TimeUnit.DAYS));
	} else {
	return TimeUnit.SECONDS.toNanos(toInstant().getEpochSecond()
	- TimeUnit.DAYS.toSeconds(days));
	}
	}

	/**
	* Compares the value of two {@code FileTime} objects for order.
	*
	* @param other
	* the other {@code FileTime} to be compared
	*
	* @return {@code 0} if this {@code FileTime} is equal to {@code other}, a
	* value less than 0 if this {@code FileTime} represents a time
	* that is before {@code other}, and a value greater than 0 if this
	* {@code FileTime} represents a time that is after {@code other}
	*/
	@Override
	public int compareTo(FileTime other) {
	// same granularity
	if (unit != null && unit == other.unit) {
	return Long.compare(value, other.value);
	} else {
	// compare using instant representation when unit differs
	long secs = toInstant().getEpochSecond();
	long secsOther = other.toInstant().getEpochSecond();
	int cmp = Long.compare(secs, secsOther);
	if (cmp != 0) {
	return cmp;
	}
	cmp = Long.compare(toInstant().getNano(), other.toInstant().getNano());
	if (cmp != 0) {
	return cmp;
	}
	if (secs != MAX_SECOND && secs != MIN_SECOND) {
	return 0;
	}
	// if both this and other's Instant reps are MIN/MAX,
	// use daysSinceEpoch and nanosOfDays, which will not
	// saturate during calculation.
	long days = toDays();
	long daysOther = other.toDays();
	if (days == daysOther) {
	return Long.compare(toExcessNanos(days), other.toExcessNanos(daysOther));
	}
	return Long.compare(days, daysOther);
	}
	}

	// days in a 400 year cycle = 146097
	// days in a 10,000 year cycle = 146097 * 25
	// seconds per day = 86400
	private static final long DAYS_PER_10000_YEARS = 146097L * 25L;
	private static final long SECONDS_PER_10000_YEARS = 146097L * 25L * 86400L;
	private static final long SECONDS_0000_TO_1970 = ((146097L * 5L) - (30L * 365L + 7L)) * 86400L;

	// append year/month/day/hour/minute/second/nano with width and 0 padding
	private StringBuilder append(StringBuilder sb, int w, int d) {
	while (w > 0) {
	sb.append((char)(d/w + '0'));
	d = d % w;
	w /= 10;
	}
	return sb;
	}

	/**
	* Returns the string representation of this {@code FileTime}. The string
	* is returned in the <a
	* href="http://www.w3.org/TR/NOTE-datetime">ISO 8601</a> format:
	* <pre>
	* YYYY-MM-DDThh:mm:ss[.s+]Z
	* </pre>
	* where "{@code [.s+]}" represents a dot followed by one of more digits
	* for the decimal fraction of a second. It is only present when the decimal
	* fraction of a second is not zero. For example, {@code
	* FileTime.fromMillis(1234567890000L).toString()} yields {@code
	* "2009-02-13T23:31:30Z"}, and {@code FileTime.fromMillis(1234567890123L).toString()}
	* yields {@code "2009-02-13T23:31:30.123Z"}.
	*
	* <p> A {@code FileTime} is primarily intended to represent the value of a
	* file's time stamp. Where used to represent <i>extreme values</i>, where
	* the year is less than "{@code 0001}" or greater than "{@code 9999}" then
	* this method deviates from ISO 8601 in the same manner as the
	* <a href="http://www.w3.org/TR/xmlschema-2/#deviantformats">XML Schema
	* language</a>. That is, the year may be expanded to more than four digits
	* and may be negative-signed. If more than four digits then leading zeros
	* are not present. The year before "{@code 0001}" is "{@code -0001}".
	*
	* @return the string representation of this file time
	*/
	@Override
	public String toString() {
	if (valueAsString == null) {
	long secs = 0L;
	int nanos = 0;
	if (instant == null && unit.compareTo(TimeUnit.SECONDS) >= 0) {
	secs = unit.toSeconds(value);
	} else {
	secs = toInstant().getEpochSecond();
	nanos = toInstant().getNano();
	}
	LocalDateTime ldt;
	int year = 0;
	if (secs >= -SECONDS_0000_TO_1970) {
	// current era
	long zeroSecs = secs - SECONDS_PER_10000_YEARS + SECONDS_0000_TO_1970;
	long hi = Math.floorDiv(zeroSecs, SECONDS_PER_10000_YEARS) + 1;
	long lo = Math.floorMod(zeroSecs, SECONDS_PER_10000_YEARS);
	ldt = LocalDateTime.ofEpochSecond(lo - SECONDS_0000_TO_1970, nanos, ZoneOffset.UTC);
	year = ldt.getYear() + (int)hi * 10000;
	} else {
	// before current era
	long zeroSecs = secs + SECONDS_0000_TO_1970;
	long hi = zeroSecs / SECONDS_PER_10000_YEARS;
	long lo = zeroSecs % SECONDS_PER_10000_YEARS;
	ldt = LocalDateTime.ofEpochSecond(lo - SECONDS_0000_TO_1970, nanos, ZoneOffset.UTC);
	year = ldt.getYear() + (int)hi * 10000;
	}
	if (year <= 0) {
	year = year - 1;
	}
	int fraction = ldt.getNano();
	StringBuilder sb = new StringBuilder(64);
	sb.append(year < 0 ? "-" : "");
	year = Math.abs(year);
	if (year < 10000) {
	append(sb, 1000, Math.abs(year));
	} else {
	sb.append(String.valueOf(year));
	}
	sb.append('-');
	append(sb, 10, ldt.getMonthValue());
	sb.append('-');
	append(sb, 10, ldt.getDayOfMonth());
	sb.append('T');
	append(sb, 10, ldt.getHour());
	sb.append(':');
	append(sb, 10, ldt.getMinute());
	sb.append(':');
	append(sb, 10, ldt.getSecond());
	if (fraction != 0) {
	sb.append('.');
	// adding leading zeros and stripping any trailing zeros
	int w = 100_000_000;
	while (fraction % 10 == 0) {
	fraction /= 10;
	w /= 10;
	}
	append(sb, w, fraction);
	}
	sb.append('Z');
	valueAsString = sb.toString();
	}
	return valueAsString;
	}
	}

Back to index...