格式符说明
%aAbbreviated weekday name (Sun .. Sat)
%bAbbreviated month name (Jan .. Dec)
%cMonth, numeric (0 .. 12)
%dDay of the month, numeric (00 .. 31)
%eDay of the month, numeric (0 .. 31)
%fFraction of second (6 digits for printing: 000000 .. 999000; 1 - 9 digits for parsing: 0 .. 999999999)
%HHour (00 .. 23)
%hHour (01 .. 12)
%IHour (01 .. 12)
%iMinutes, numeric (00 .. 59)
%jDay of year (001 .. 366)
%kHour (0 .. 23)
%lHour (1 .. 12)
%MMonth name (January .. December)
%mMonth, numeric (00 .. 12)
%pAM or PM
%rTime, 12-hour (hh:mm:ss followed by AM or PM)
%SSeconds (00 .. 59)
%sSeconds (00 .. 59)
%TTime, 24-hour (hh:mm:ss)
%vWeek (01 .. 53), where Monday is the first day of the week; used with %x
%WWeekday name (Sunday .. Saturday)
%YYear, numeric, four digits
%yYear, numeric (two digits)
%%A literal % character
%xx, for any x not listed above