org.apache.commons.net.ntp
Class TimeStamp

java.lang.Object
  org.apache.commons.net.ntp.TimeStamp

All Implemented Interfaces:

Serializable, Comparable

public class TimeStamp
extends Object
implements Serializable, Comparable

TimeStamp class represents the Network Time Protocol (NTP) timestamp as defined in RFC-1305 and SNTP (RFC-2030). It is represented as a 64-bit unsigned fixed-point number in seconds relative to 0-hour on 1-January-1900. The 32-bit low-order bits are the fractional seconds whose precision is about 200 picoseconds. Assumes overflow date when date passes MAX_LONG and reverts back to 0 is 2036 and not 1900. Test for most significant bit: if MSB=0 then 2036 basis is used otherwise 1900 if MSB=1.

Methods exist to convert NTP timestamps to and from the equivalent Java date representation, which is the number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.

Version:

$Revision: 165675 $ $Date: 2005-05-02 21:09:55 +0100 (Mon, 02 May 2005) $

Author:

Jason Mathews, MITRE Corp

See Also:

Date, Serialized Form

Field Summary

protected static long	msb0baseTime baseline NTP time if bit-0=0 -> 7-Feb-2036 @ 06:28:16 UTC
protected static long	msb1baseTime baseline NTP time if bit-0=1 -> 1-Jan-1900 @ 01:00:00 UTC
static String	NTP_DATE_FORMAT Default NTP date string format.

Constructor Summary

TimeStamp(Date d)
Constructs a newly allocated NTP timestamp object that represents the Java Date argument.

TimeStamp(long ntpTime)
Constructs a newly allocated NTP timestamp object that represents the native 64-bit long argument.

TimeStamp(String s)
Constructs a newly allocated NTP timestamp object that represents the value represented by the string in hexdecimal form (e.g.

Method Summary

int	compareTo(Object o) Compares this TimeStamp to another Object.
int	compareTo(TimeStamp anotherTimeStamp) Compares two Timestamps numerically.
protected static long	decodeNtpHexString(String s) Convert NTP timestamp hexstring (e.g.
boolean	equals(Object obj) Compares this object against the specified object.
static TimeStamp	getCurrentTime() Constructs a NTP timestamp object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.
Date	getDate() Convert NTP timestamp to Java Date object.
long	getFraction() Returns low-order 32-bits representing the fractional seconds.
static TimeStamp	getNtpTime(long date) Helper method to convert Java time to NTP timestamp object.
long	getSeconds() Returns high-order 32-bits representing the seconds of this NTP timestamp.
long	getTime() Convert NTP timestamp to Java standard time.
static long	getTime(long ntpTimeValue) Convert 64-bit NTP timestamp to Java standard time.
int	hashCode() Computes a hashcode for this Timestamp.
long	ntpValue() Returns the value of this Timestamp as a long value.
static TimeStamp	parseNtpString(String s) Parses the string argument as a NTP hexidecimal timestamp representation string (e.g.
String	toDateString() Converts this TimeStamp object to a String of the form:
protected static long	toNtpTime(long t) Converts Java time to 64-bit NTP time representation.
String	toString() Converts this TimeStamp object to a String.
static String	toString(long ntpTime) Converts 64-bit NTP timestamp value to a String.
String	toUTCString() Converts this TimeStamp object to a String of the form:

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

msb0baseTime

protected static final long msb0baseTime

baseline NTP time if bit-0=0 -> 7-Feb-2036 @ 06:28:16 UTC

See Also:

Constant Field Values

msb1baseTime

protected static final long msb1baseTime

baseline NTP time if bit-0=1 -> 1-Jan-1900 @ 01:00:00 UTC

See Also:

Constant Field Values

NTP_DATE_FORMAT

public static final String NTP_DATE_FORMAT

Default NTP date string format. E.g. Fri, Sep 12 2003 21:06:23.860. See java.text.SimpleDateFormat for code descriptions.

See Also:

Constant Field Values

Constructor Detail

TimeStamp

public TimeStamp(long ntpTime)

Constructs a newly allocated NTP timestamp object that represents the native 64-bit long argument.

TimeStamp

public TimeStamp(String s)
          throws NumberFormatException

Constructs a newly allocated NTP timestamp object that represents the value represented by the string in hexdecimal form (e.g. "c1a089bd.fc904f6d").

Throws:

NumberFormatException - - if the string does not contain a parsable timestamp.

TimeStamp

public TimeStamp(Date d)

Constructs a newly allocated NTP timestamp object that represents the Java Date argument.

Parameters:

d - - the Date to be represented by the Timestamp object.

Method Detail

ntpValue

public long ntpValue()

Returns the value of this Timestamp as a long value.

Returns:

the 64-bit long value represented by this object.

getSeconds

public long getSeconds()

Returns high-order 32-bits representing the seconds of this NTP timestamp.

Returns:

seconds represented by this NTP timestamp.

getFraction

public long getFraction()

Returns low-order 32-bits representing the fractional seconds.

Returns:

fractional seconds represented by this NTP timestamp.

getTime

public long getTime()

Convert NTP timestamp to Java standard time.

Returns:

NTP Timestamp in Java time

getDate

public Date getDate()

Convert NTP timestamp to Java Date object.

Returns:

NTP Timestamp in Java Date

getTime

public static long getTime(long ntpTimeValue)

Convert 64-bit NTP timestamp to Java standard time. Note that java time (milliseconds) by definition has less precision then NTP time (picoseconds) so converting NTP timestamp to java time and back to NTP timestamp loses precision. For example, Tue, Dec 17 2002 09:07:24.810 EST is represented by a single Java-based time value of f22cd1fc8a, but its NTP equivalent are all values ranging from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.

Parameters:

ntpTimeValue -

Returns:

the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this NTP timestamp value.

getNtpTime

public static TimeStamp getNtpTime(long date)

Helper method to convert Java time to NTP timestamp object. Note that Java time (milliseconds) by definition has less precision then NTP time (picoseconds) so converting Ntptime to Javatime and back to Ntptime loses precision. For example, Tue, Dec 17 2002 09:07:24.810 is represented by a single Java-based time value of f22cd1fc8a, but its NTP equivalent are all values from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.

Parameters:

date - the milliseconds since January 1, 1970, 00:00:00 GMT.

Returns:

NTP timestamp object at the specified date.

getCurrentTime

public static TimeStamp getCurrentTime()

Constructs a NTP timestamp object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.

Returns:

NTP timestamp object set to the current time.

See Also:

System.currentTimeMillis()

decodeNtpHexString

protected static long decodeNtpHexString(String s)
                                  throws NumberFormatException

Convert NTP timestamp hexstring (e.g. "c1a089bd.fc904f6d") to the NTP 64-bit unsigned fixed-point number.

Returns:

NTP 64-bit timestamp value.

Throws:

NumberFormatException - - if the string does not contain a parsable timestamp.

parseNtpString

public static TimeStamp parseNtpString(String s)
                                throws NumberFormatException

Parses the string argument as a NTP hexidecimal timestamp representation string (e.g. "c1a089bd.fc904f6d").

Parameters:

s - - hexstring.

Returns:

the Timestamp represented by the argument in hexidecimal.

Throws:

NumberFormatException - - if the string does not contain a parsable timestamp.

toNtpTime

protected static long toNtpTime(long t)

Converts Java time to 64-bit NTP time representation.

Parameters:

t - Java time

Returns:

NTP timestamp representation of Java time value.

hashCode

public int hashCode()

Computes a hashcode for this Timestamp. The result is the exclusive OR of the two halves of the primitive long value represented by this TimeStamp object. That is, the hashcode is the value of the expression:

 (int)(this.ntpValue()^(this.ntpValue() >>> 32))
 

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

equals

public boolean equals(Object obj)

Compares this object against the specified object. The result is true if and only if the argument is not null and is a Long object that contains the same long value as this object.

Overrides:

equals in class Object

Parameters:

obj - the object to compare with.

Returns:

true if the objects are the same; false otherwise.

toString

public String toString()

Converts this TimeStamp object to a String. The NTP timestamp 64-bit long value is represented as hex string with seconds separated by fractional seconds by a decimal point; e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986

Overrides:

toString in class Object

Returns:

NTP timestamp 64-bit long value as hex string with seconds separated by fractional seconds.

toString

public static String toString(long ntpTime)

Converts 64-bit NTP timestamp value to a String. The NTP timestamp value is represented as hex string with seconds separated by fractional seconds by a decimal point; e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986

Returns:

NTP timestamp 64-bit long value as hex string with seconds separated by fractional seconds.

toDateString

public String toDateString()

Converts this TimeStamp object to a String of the form:

 EEE, MMM dd yyyy HH:mm:ss.SSS

See java.text.SimpleDataFormat for code descriptions.

Returns:

a string representation of this date.

toUTCString

public String toUTCString()

Converts this TimeStamp object to a String of the form:

 EEE, MMM dd yyyy HH:mm:ss.SSS UTC

See java.text.SimpleDataFormat for code descriptions.

Returns:

a string representation of this date in UTC.

compareTo

public int compareTo(TimeStamp anotherTimeStamp)

Compares two Timestamps numerically.

Parameters:

anotherTimeStamp - - the TimeStamp to be compared.

Returns:

the value 0 if the argument TimeStamp is equal to this TimeStamp; a value less than 0 if this TimeStamp is numerically less than the TimeStamp argument; and a value greater than 0 if this TimeStamp is numerically greater than the TimeStamp argument (signed comparison).

compareTo

public int compareTo(Object o)

Compares this TimeStamp to another Object. If the Object is a TimeStamp, this function behaves like compareTo(TimeStamp). Otherwise, it throws a ClassCastException (as TimeStamps are comparable only to other TimeStamps).

Specified by:

compareTo in interface Comparable

Parameters:

o - the Object to be compared.

Returns:

the value 0 if the argument is a TimeStamp numerically equal to this TimeStamp; a value less than 0 if the argument is a TimeStamp numerically greater than this TimeStamp; and a value greater than 0 if the argument is a TimeStamp numerically less than this TimeStamp.

Throws:

ClassCastException - if the argument is not a TimeStamp.

See Also:

Comparable