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@force2be Time / Timezone conversions

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  1. //http://www.force2b.net/index.php/2010/08/date-time-and-timezone-handling-in-apex/
  2.  
  3. /* **********************************************************************************************
  4. * TimeConversions Class
  5. * Created by: Michael Smith/Force2b, 04/06/2010
  6. *
  7. ************************************************************************************************ */
  8. global class TimeConversions {
  9.  
  10.    /* -------------------------------------------------------------------------------------
  11.    * Returns an Integer  of the Timezone Offset from Eastern Time for the
  12.    * currently logged in user
  13.    *
  14.    * This is used to convert the String DateTime (that is in Eastern Time) into a
  15.    * DateTime value in SalesForce. The default behavior of SFC converts the string into
  16.    * a local datetime value, but we need to get into Eastern Time.
  17.    * ------------------------------------------------------------------------------------- */
  18.    public Integer getCurrentUserTZOffsetFromEastern() {
  19.  
  20.       Map<String, Integer[]> tzSIDKeys = getTZSidKeys();
  21.  
  22.       User user = [SELECT ID, TimeZoneSidKey FROM User WHERE ID = :UserInfo.getUserId() LIMIT 1];
  23.  
  24.       Date[] dstDatesNow = getDSTDates(System.Today().year());
  25.       Integer UsersTZOffset = 0;
  26.  
  27.       if (tzSIDKeys.get(user.TimeZoneSidKey) != null) {
  28.          // Get the base timezone offset from GMT for the user
  29.          if (System.Today() >= dstDatesNow[0] && System.Today() <= dstDatesNow[1]) UsersTZOffset = tzSIDKeys.get(user.TimeZoneSidKey)[1];
  30.          else UsersTZOffset = tzSIDKeys.get(user.TimeZoneSidKey)[0];
  31.          system.debug(LoggingLevel.Error, 'Base TimeZone for Current User=' + user.TimeZoneSidKey + '/' + UsersTZOffset );
  32.  
  33.          // Now make it a timezone offset from EASTERN time
  34.          Integer EasternTZOffset = 0;
  35.          if (System.Today() >= dstDatesNow[0] && System.Today() <= dstDatesNow[1]) EasternTZOffset = tzSIDKeys.get('America/New_York')[1];
  36.          else EasternTZOffset = tzSIDKeys.get('America/New_York')[0];
  37.          UsersTZOffset = Math.abs(EasternTZOffset) - Math.abs(UsersTZOffset);
  38.          system.debug(LoggingLevel.Error, 'TimeZone Offset to Eastern Time=' + UsersTZOffset );
  39.       }
  40.       return UsersTZOffset ;
  41.    }
  42.  
  43.    /* -------------------------------------------------------------------------------------
  44.    * Returns a String Collection of the Timezone Codes based on the Timezone Offset Passed
  45.    * for the date passed.
  46.    *
  47.    * Based on a table from: http://en.wikipedia.org/wiki/Zone.tab
  48.    *
  49.    * getTimeZoneCode[0] = Display Text (ex: EDT)
  50.    * getTimeZoneCode[1] = DateTime.Format() parameter (ex: America/New_York)
  51.    * ------------------------------------------------------------------------------------- */
  52.    public string[] getTimeZoneCode(Integer tzOffset, Date theDate, Boolean isDSTObserved) {
  53.       Date[] dstDates = getDSTDates(theDate.year()); // [0]=startDate, [1]=endDate
  54.       boolean isDSTOn = (theDate >= dstDates[0] && theDate <= dstDates[1]);
  55.  
  56.       if (tzOffset == 0) return new String[]{' GMT', 'Europe/London' };
  57.       else if (tzOffset == 4) return new String[]{' AST (UTC-04)', 'America/Puerto_Rico' };
  58.       else if (tzOffset == 5 && isDSTOn && isDSTObserved) return new String[]{' EDT (UTC-04)', 'America/New_York' };
  59.       else if (tzOffset == 5) return new String[]{' EST (UTC-05)', 'America/New_York' };
  60.       else if (tzOffset == 6 && isDSTOn && isDSTObserved) return new String[]{' CDT (UTC-05)', 'America/Chicago' };
  61.       else if (tzOffset == 6) return new String[]{' CST (UTC-06)', 'America/Chicago' };
  62.       else if (tzOffset == 7 && !isDSTObserved)         return new String[]{' MST (UTC-07)', 'America/Phoenix' };
  63.       else if (tzOffset == 7 && isDSTOn && isDSTObserved) return new String[]{' MDT (UTC-06)', 'America/Denver' };
  64.       else if (tzOffset == 7) return new String[]{' MST (UTC-07)', 'America/Denver' };
  65.       else if (tzOffset == 8 && isDSTOn && isDSTObserved) return new String[]{' PDT (UTC-07)', 'America/Los_Angeles' };
  66.       else if (tzOffset == 8) return new String[]{' PST (UTC-08)', 'America/Los_Angeles' };
  67.       else if (tzOffset == 9 && isDSTOn && isDSTObserved) return new String[]{' AKDT (UTC-08)', 'America/Anchorage' };
  68.       else if (tzOffset == 9) return new String[]{' AKST (UTC-09)', 'America/Anchorage' };
  69.       else if (tzOffset == 10 && !isDSTObserved)        return new String[]{' HST (UTC-10)', 'Pacific/Honolulu' };
  70.       else if (tzOffset == 10 && isDSTOn && isDSTObserved) return new String[]{' HDT (UTC-09)', 'America/Adak' };
  71.       else if (tzOffset == 10) return new String[]{' HST (UTC-10)', 'America/Adak' };
  72.       else if (tzOffset == 11) return new String[]{' HST (UTC-10)', 'Pacific/Pago_Pago' };
  73.       else return new String[]{' UTC-' + tzOffset, 'GMT' };
  74.    }
  75.  
  76.    /* -------------------------------------------------------------------------------------
  77.    * Returns a date Collection of Start/End dates for US Daylight Saving Time
  78.    * for the specified year.
  79.    *
  80.    * Based on code from: http://www.webexhibits.org/daylightsaving/b2.html
  81.    * ------------------------------------------------------------------------------------- */
  82.    public Date[] getDSTDates(Integer theYear) {
  83.       Long thisYear;
  84.       Long AprilDate;
  85.       Long OctoberDate;
  86.       Long MarchDate;
  87.       Long NovemberDate;
  88.       Long longSeven = 7;
  89.       thisYear = Math.round(theYear);
  90.  
  91.       AprilDate = Math.mod(2+6 * thisYear - Math.floor(thisYear / 4).longValue(), longSeven) + 1;
  92.       OctoberDate=  Math.mod(31-( Math.floor(thisYear * 5 / 4).longValue() + 1), longSeven);
  93.  
  94.       MarchDate = 14 - Math.mod(Math.floor(1 + thisYear * 5 / 4).LongValue(), longSeven);
  95.       NovemberDate = 7 - Math.mod(Math.floor (1 + thisYear * 5 / 4).LongValue(), longSeven);
  96.  
  97.       string startDate = (thisYear > 2006 ? ('03/'+MarchDate) : ('04/'+AprilDate)) + '/' + thisYear;
  98.       string endDate = (thisYear > 2006 ? ('11/'+NovemberDate):('10/'+OctoberDate))+ '/' + thisYear;
  99.  
  100.       Date[] rtnDates = new List<Date>();
  101.       rtnDates.add(Date.parse(startDate));
  102.       rtnDates.add(Date.parse(endDate));
  103.       return rtnDates;
  104.    }
  105.  
  106.    public Map<String, Integer[]> getTZSidKeys() {
  107.       Map<String, Integer[]> tzSIDKeys = new Map<String, Integer[]>();
  108.       tzSIDKeys.put('America/Adak', new Integer[]{-10, -9});
  109.       tzSIDKeys.put('America/Anchorage', new Integer[]{-9, -8});
  110.       tzSIDKeys.put('America/Chicago', new Integer[]{-6, -5});
  111.       tzSIDKeys.put('America/Denver', new Integer[]{-7, -6});
  112.       tzSIDKeys.put('America/Detroit', new Integer[]{-5, -4});
  113.       tzSIDKeys.put('America/Halifax', new Integer[]{-4, -3});
  114.       tzSIDKeys.put('America/Indianapolis', new Integer[]{-5, -4});
  115.       tzSIDKeys.put('America/Los_Angeles', new Integer[]{-8, -7});
  116.       tzSIDKeys.put('America/Montreal', new Integer[]{-5, -4});
  117.       tzSIDKeys.put('America/New_York', new Integer[]{-5, -4});
  118.       tzSIDKeys.put('America/Panama', new Integer[]{-5, -5});
  119.       tzSIDKeys.put('America/Phoenix', new Integer[]{-7, -7});
  120.       tzSIDKeys.put('America/Puerto_Rico', new Integer[]{-4, -4});
  121.       tzSIDKeys.put('America/Toronto', new Integer[]{-5, -4});
  122.       tzSIDKeys.put('America/Vancouver', new Integer[]{-8, -7});
  123.       tzSIDKeys.put('Europe/London', new Integer[]{0, 1});
  124.       tzSIDKeys.put('Pacific/Honolulu', new Integer[]{-10, -10});
  125.       tzSIDKeys.put('Pacific/Pago_Pago', new Integer[]{-11, -11});
  126.  
  127.       return tzSIDKeys;
  128.    }
  129. }
  130.  

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