Ruby--時間，日期 用法

基本的時間轉換
>> now=Time.now
=> Sat Jan 29 21:47:07 0800 2011
#utc秒數互相轉換
>> now.to_i
=> 1296308827
>> Time.at(1296308827)
=> Sat Jan 29 21:47:07 0800 2011
#當前時間的一些變量
>> now.sec
=> 7
>> now.min
=> 47
>> now.hour
=> 21
>> now.month
=> 1
>> now.year
=> 2011
#現在是星期幾(注意!!!週日是返回 0 )
>> now.wday
=> 6
#現在是本月第幾天
>> now.day
=> 29
#現在是今年第幾天
>> now.yday
=> 29
#時間參數的數組
>> now.to_a
=> [7, 47, 21, 29, 1, 2011, 6, 29, false, "CST"]

時間化輸出
>> now.strftime("%Y-%m-%d %H:%M:%S")
=> "2011-01-29 21:47:07"

參數解釋如下

  %a - 星期幾的英文簡寫 (``Sun'')
  %A - 星期幾的英文全稱 (``Sunday'')
  %b - 月份的英文簡寫 (``Jan'')
  %B - 月份的英文全稱 (``January'')
  %c - 默認的首選本地時間輸出格式
  %d - 本月第幾天 (01..31)
  %H - 24小時制的小時 (00..23)
  %I - 12小時制的小時 (01..12)
  %j - 今年的第幾天 (001..366)
  %m - 月份 (01..12)
  %M - 分鐘 (00..59)
  %p - 上午還是下午 (``AM''  or  ``PM'')
  %S - 秒數 (00..60)
  %U - 從星期天算一週開始的本年第幾周 (00..53)
  %W - 從星期一算一週開始的本年第幾周 (00..53)
  %w - 現在是星期幾 (週日是0 , 0..6)
  %x - 默認的日期輸出格式 ("01/29/11")
  %X - 默認的時間輸出格式 ("21:47:07")
  %y - 年份的後兩位 (00..99)
  %Y - 年份
  %Z - 時區名
  %% - 輸出%字符

以上是ruby的基本方法，rails對其做了更多的擴展

#重寫了to_s方法，能夠接受參數
>> now.to_s
=> "Sat Jan 29 21:47:07 +0800 2011"
>> now.to_s(:db)
=> "2011-01-29 21:47:07"
>> now.to_s(:number)
=> "20110129214707"
>> now.to_s(:time)
=> "21:47"
>> now.to_s(:short)
=> "29 Jan 21:47"
>> now.to_s(:long)
=> "January 29, 2011 21:47"
>> now.to_s(:long_ordinal)
=> "January 29th, 2011 21:47"
>> now.to_s(:rfc822)
=> "Sat, 29 Jan 2011 21:47:07 +0800"

如果要自己設計時間輸出格式，按下面方法來，新建一個配置文件

  # config/initializers/time_formats.rb
  Time::DATE_FORMATS[:month_and_year] = "%B %Y"
  Time::DATE_FORMATS[:short_ordinal] = lambda { |time| time.strftime("%B #{time.day.ordinalize}") }

rails對日期的一些擴展

#指定時間
>> now.change(:year=>2012, :month=>12, :day => 21, :hour => 0, :min => 0, :sec => 0, :usec => 0)
=> Fri Dec 21 00:00:00 0800 2012

#begginning家族
>> now.beginning_of_day
=> Sat Jan 29 00:00:00 0800 2011
>> now.midnight
=> Sat Jan 29 00:00:00 0800 2011
>> now.beginning_of_week
=> Mon Jan 24 00:00:00 0800 2011
>> now.beginning_of_month
=> Sat Jan 01 00:00:00 0800 2011
>> now.beginning_of_quarter
=> Sat Jan 01 00:00:00 0800 2011
>> now.beginning_of_year
=> Sat Jan 01 00:00:00 0800 2011
#end家族
>> now.end_of_day
=> Sat Jan 29 23:59:59 0800 2011
>> now.end_of_week
=> Sun Jan 30 23:59:59 0800 2011
>> now.end_of_month
=> Mon Jan 31 23:59:59 0800 2011
>> now.end_of_quarter
=> Thu Mar 31 23:59:59 0800 2011
>> now.end_of_year
=> Sat Dec 31 23:59:59 0800 2011
#時間的魔術方法
>> now.yesterday
=> Fri Jan 28 21:47:07 0800 2011
>> now.tomorrow
=> Sun Jan 30 21:47:07 0800 2011
>> now.next_week
=> Mon Jan 31 00:00:00 0800 2011
>> now.next_month
=> Mon Feb 28 21:47:07 0800 2011
>> now.next_year
#注意沒有prev_week
>> now.prev_month
=> Wed Dec 29 21:47:07 0800 2010
>> now.prev_year
=> Fri Jan 29 21:47:07 0800 2010
#今日已過秒數
>> now.seconds_since_midnight
=> 78427.615017
#日期輸出
>> now.to_date
=> Sat, 29 Jan 2011
>> now.to_datetime
=> Sat, 29 Jan 2011 21:47:07 0800
#按秒數計算
>> now.ago(3600)
=> Sat Jan 29 20:47:07 0800 2011
>> now.since(3600)
=> Sat Jan 29 22:47:07 0800 2011