tim/prune/data/Timestamp.java

   1 package tim.prune.data;
   2
   3 import java.text.DateFormat;
   4 import java.text.ParseException;
   5 import java.text.SimpleDateFormat;
   6 import java.util.Calendar;
   7 import java.util.Date;
   8
   9 /**
  10  * Class to hold the timestamp of a track point
  11  * and provide conversion functions
  12  */
  13 public class Timestamp
  14 {
  15         private boolean _valid = false;
  16         private long _seconds = 0L;
  17         private String _text = null;
  18
  19         private static DateFormat DEFAULT_DATE_FORMAT = DateFormat.getDateTimeInstance();
  20         private static DateFormat[] ALL_DATE_FORMATS = null;
  21         private static Calendar CALENDAR = null;
  22         private static long SECS_SINCE_1970 = 0L;
  23         private static long SECS_SINCE_GARTRIP = 0L;
  24         private static long MSECS_SINCE_1970 = 0L;
  25         private static long MSECS_SINCE_1990 = 0L;
  26         private static long TWENTY_YEARS_IN_SECS = 0L;
  27
  28         private static final long GARTRIP_OFFSET = 631065600L;
  29
  30         // Static block to initialise offsets
  31         static
  32         {
  33                 CALENDAR = Calendar.getInstance();
  34                 MSECS_SINCE_1970 = CALENDAR.getTimeInMillis();
  35                 SECS_SINCE_1970 = MSECS_SINCE_1970 / 1000L;
  36                 SECS_SINCE_GARTRIP = SECS_SINCE_1970 - GARTRIP_OFFSET;
  37                 CALENDAR.add(Calendar.YEAR, -20);
  38                 MSECS_SINCE_1990 = CALENDAR.getTimeInMillis();
  39                 TWENTY_YEARS_IN_SECS = (MSECS_SINCE_1970 - MSECS_SINCE_1990) / 1000L;
  40                 // Date formats
  41                 ALL_DATE_FORMATS = new DateFormat[] {
  42                         DEFAULT_DATE_FORMAT,
  43                         new SimpleDateFormat("EEE MMM dd HH:mm:ss yyyy"),
  44                         new SimpleDateFormat("HH:mm:ss dd MMM yyyy"),
  45                         new SimpleDateFormat("dd MMM yyyy HH:mm:ss"),
  46                         new SimpleDateFormat("yyyy MMM dd HH:mm:ss")
  47                 };
  48         }
  49
  50
  51         /**
  52          * Constructor
  53          */
  54         public Timestamp(String inString)
  55         {
  56                 if (inString != null && !inString.equals(""))
  57                 {
  58                         // Try to parse into a long
  59                         try
  60                         {
  61                                 long rawValue = Long.parseLong(inString.trim());
  62                                 // check for each format possibility and pick nearest
  63                                 long diff1 = Math.abs(SECS_SINCE_1970 - rawValue);
  64                                 long diff2 = Math.abs(MSECS_SINCE_1970 - rawValue);
  65                                 long diff3 = Math.abs(MSECS_SINCE_1990 - rawValue);
  66                                 long diff4 = Math.abs(SECS_SINCE_GARTRIP - rawValue);
  67
  68                                 // Start off with "seconds since 1970" format
  69                                 long smallestDiff = diff1;
  70                                 _seconds = rawValue;
  71                                 // Now check millis since 1970
  72                                 if (diff2 < smallestDiff)
  73                                 {
  74                                         // milliseconds since 1970
  75                                         _seconds = rawValue / 1000L;
  76                                         smallestDiff = diff2;
  77                                 }
  78                                 // Now millis since 1990
  79                                 if (diff3 < smallestDiff)
  80                                 {
  81                                         // milliseconds since 1990
  82                                         _seconds = rawValue / 1000L + TWENTY_YEARS_IN_SECS;
  83                                         smallestDiff = diff3;
  84                                 }
  85                                 // Lastly, check garmin offset
  86                                 if (diff4 < smallestDiff)
  87                                 {
  88                                         // milliseconds since garmin offset
  89                                         _seconds = rawValue + GARTRIP_OFFSET;
  90                                 }
  91                                 _valid = true;
  92                         }
  93                         catch (NumberFormatException nfe)
  94                         {
  95                                 // String is not a long, so try a date/time string instead
  96                                 // try each of the date formatters in turn
  97                                 Date date = null;
  98                                 for (int i=0; i<ALL_DATE_FORMATS.length && !_valid; i++)
  99                                 {
 100                                         try
 101                                         {
 102                                                 date = ALL_DATE_FORMATS[i].parse(inString);
 103                                                 CALENDAR.setTime(date);
 104                                                 _seconds = CALENDAR.getTimeInMillis() / 1000L;
 105                                                 _valid = true;
 106                                         }
 107                                         catch (ParseException e) {}
 108                                 }
 109                         }
 110                 }
 111         }
 112
 113
 114         /**
 115          * @return true if timestamp is valid
 116          */
 117         public boolean isValid()
 118         {
 119                 return _valid;
 120         }
 121
 122
 123         /**
 124          * Calculate the difference between two Timestamps in seconds
 125          * @param inOther other, earlier Timestamp
 126          * @return number of seconds since other timestamp
 127          */
 128         public long getSecondsSince(Timestamp inOther)
 129         {
 130                 return _seconds - inOther._seconds;
 131         }
 132
 133
 134         /**
 135          * @return Description of timestamp in locale-specific format
 136          */
 137         public String getText()
 138         {
 139                 if (_text == null)
 140                 {
 141                         if (_valid)
 142                         {
 143                                 CALENDAR.setTimeInMillis(_seconds * 1000L);
 144                                 _text = DEFAULT_DATE_FORMAT.format(CALENDAR.getTime());
 145                         }
 146                         else _text = "";
 147                 }
 148                 return _text;
 149         }
 150 }