Package org.apache.commons.net.ntp

Class TimeStamp

java.lang.Object
org.apache.commons.net.ntp.TimeStamp
All Implemented Interfaces:
Serializable, Comparable<TimeStamp>
public class TimeStamp extends Object implements Serializable, Comparable<TimeStamp>
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.

See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected static final long
    msb0baseTime
    Baseline NTP time if bit-0=0 is 7-Feb-2036 @ 06:28:16 UTC
    protected static final long
    msb1baseTime
    Baseline NTP time if bit-0=1 is 1-Jan-1900 @ 01:00:00 UTC
    static final String
    NTP_DATE_FORMAT
    Default NTP date string format.

  • Constructor Summary

    Constructors
    Constructor
    Description
    TimeStamp(long ntpTime)
    Constructs a newly allocated NTP timestamp object that represents the native 64-bit long argument.
    TimeStamp(String hexStamp)
    Constructs a newly allocated NTP timestamp object that represents the value represented by the string in hexdecimal form (e.g.
    TimeStamp(Date d)
    Constructs a newly allocated NTP timestamp object that represents the Java Date argument.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    compareTo(TimeStamp anotherTimeStamp)
    Compares two Timestamps numerically.
    protected static long
    decodeNtpHexString(String hexString)
    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()
    Converts NTP timestamp to Java Date object.
    long
    getFraction()
    Returns low-order 32-bits representing the fractional seconds.
    static TimeStamp
    getNtpTime(long dateMillis)
    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()
    Converts NTP timestamp to Java standard time.
    static long
    getTime(long ntpTimeValue)
    Converts 64-bit NTP timestamp to Java standard time.
    int
    hashCode()
    Computes a hash code 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 millis)
    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 Details

  • Constructor Details

    • 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.

    • TimeStamp

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

    • TimeStamp

      public TimeStamp(String hexStamp) throws NumberFormatException
      Constructs a newly allocated NTP timestamp object that represents the value represented by the string in hexdecimal form (e.g. "c1a089bd.fc904f6d").
      Parameters:
      hexStamp - the hex timestamp
      Throws:
      NumberFormatException - - if the string does not contain a parsable timestamp.

  • Method Details

    • decodeNtpHexString

      protected static long decodeNtpHexString(String hexString) throws NumberFormatException
      Convert NTP timestamp hexstring (e.g. "c1a089bd.fc904f6d") to the NTP 64-bit unsigned fixed-point number.
      Parameters:
      hexString - the string to convert
      Returns:
      NTP 64-bit timestamp value.
      Throws:
      NumberFormatException - - if the string does not contain a parsable timestamp.

    • 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:

    • getNtpTime

      public static TimeStamp getNtpTime(long dateMillis)
      Helper method to convert Java time to NTP timestamp object. Note that Java time (milliseconds) by definition has less precision than 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:
      dateMillis - the milliseconds since January 1, 1970, 00:00:00 GMT.
      Returns:
      NTP timestamp object at the specified date.

    • getTime

      public static long getTime(long ntpTimeValue)
      Converts 64-bit NTP timestamp to Java standard time. Note that java time (milliseconds) by definition has less precision than 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 - the input time
      Returns:
      the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this NTP timestamp value.

    • 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 millis)
      Converts Java time to 64-bit NTP time representation.
      Parameters:
      millis - Java time
      Returns:
      NTP timestamp representation of Java time value.

    • 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
      Parameters:
      ntpTime - the 64 bit timestamp
      Returns:
      NTP timestamp 64-bit long value as hex string with seconds separated by fractional seconds.

    • compareTo

      public int compareTo(TimeStamp anotherTimeStamp)
      Compares two Timestamps numerically.
      Specified by:
      compareTo in interface Comparable<TimeStamp>
      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).

    • 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.

    • getDate

      public Date getDate()
      Converts NTP timestamp to Java Date object.
      Returns:
      NTP Timestamp in Java Date

    • getFraction

      public long getFraction()
      Returns low-order 32-bits representing the fractional seconds.
      Returns:
      fractional seconds represented by this NTP timestamp.

    • getSeconds

      public long getSeconds()
      Returns high-order 32-bits representing the seconds of this NTP timestamp.
      Returns:
      seconds represented by this NTP timestamp.

    • getTime

      public long getTime()
      Converts NTP timestamp to Java standard time.
      Returns:
      the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this NTP timestamp value.

    • hashCode

      public int hashCode()
      Computes a hash code 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 hash code 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.

    • ntpValue

      public long ntpValue()
      Returns the value of this Timestamp as a long value.
      Returns:
      the 64-bit long value represented by this object.

    • 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.

    • 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.

    • 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.