python-时间日期处理

• 原则, 以datetime为中心, 起点或中转, 转化为目标对象, 涵盖了大多数业务场景中需要的日期转换处理

步骤:

1. 掌握几种对象及其关系
2. 了解每类对象的基本操作方法
3. 通过转化关系转化

涉及对象

1. datetime

   >>> import datetime
   >>> now = datetime.datetime.now()
   >>> now
   datetime.datetime(2015, 1, 12, 23, 9, 12, 946118)
   >>> type(now)
   <type 'datetime.datetime'>

2. timestamp

   >>> import time
   >>> time.time()
   1421075455.568243

3. time tuple

   >>> import time
   >>> time.localtime()
   time.struct_time(tm_year=2015, tm_mon=1, tm_mday=12, tm_hour=23, tm_min=10, tm_sec=30, tm_wday=0, tm_yday=12, tm_isdst=0)

4. string

   >>> import datetime
   >>> datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
   '2015-01-12 23:13:08'

5. date

   >>> import datetime
   >>> datetime.datetime.now().date()
   datetime.date(2015, 1, 12)

datetime基本操作

1. 获取当前datetime

   >>> import datetime
   >>> datetime.datetime.now()
   datetime.datetime(2015, 1, 12, 23, 26, 24, 475680)

2. 获取当天date

   >>> datetime.date.today()
   datetime.date(2015, 1, 12)

3. 获取明天/前N天

明天

>>> datetime.date.today() + datetime.timedelta(days=1)
datetime.date(2015, 1, 13)

三天前

>>> datetime.datetime.now()
datetime.datetime(2015, 1, 12, 23, 38, 55, 492226)
>>> datetime.datetime.now() - datetime.timedelta(days=3)
datetime.datetime(2015, 1, 9, 23, 38, 57, 59363)

4. 获取当天开始和结束时间(00:00:00 23:59:59)

   >>> datetime.datetime.combine(datetime.date.today(), datetime.time.min)
   datetime.datetime(2015, 1, 12, 0, 0)
   >>> datetime.datetime.combine(datetime.date.today(), datetime.time.max)
   datetime.datetime(2015, 1, 12, 23, 59, 59, 999999)

5. 获取两个datetime的时间差

   >>> (datetime.datetime(2015,1,13,12,0,0) - datetime.datetime.now()).total_seconds()
   44747.768075

6. 获取本周/本月/上月最后一天

本周

>>> today = datetime.date.today()
>>> today
datetime.date(2015, 1, 12)
>>> sunday = today + datetime.timedelta(6 - today.weekday())
>>> sunday
datetime.date(2015, 1, 18)

本月

>>> import calendar
>>> today = datetime.date.today()
>>> _, last_day_num = calendar.monthrange(today.year, today.month)
>>> last_day = datetime.date(today.year, today.month, last_day_num)
>>> last_day
datetime.date(2015, 1, 31)

获取上个月的最后一天(可能跨年)

>>> import datetime
>>> today = datetime.date.today()
>>> first = datetime.date(day=1, month=today.month, year=today.year)
>>> lastMonth = first - datetime.timedelta(days=1)

关系转换

几个关系之间的转化

Datetime Object / String / timestamp / time tuple

关系转换例子

datetime <=> string
datetime -> string

>>> import datetime
>>> datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
'2015-01-12 23:13:08'

string -> datetime

>>> import datetime
>>> datetime.datetime.strptime("2014-12-31 18:20:10", "%Y-%m-%d %H:%M:%S")
datetime.datetime(2014, 12, 31, 18, 20, 10)

datetime <=> timetuple
datetime -> timetuple

>>> import datetime
>>> datetime.datetime.now().timetuple()
time.struct_time(tm_year=2015, tm_mon=1, tm_mday=12, tm_hour=23, tm_min=17, tm_sec=59, tm_wday=0, tm_yday=12, tm_isdst=-1)

timetuple -> datetime

timetuple => timestamp => datetime [看后面datetime<=>timestamp]

datetime <=> date
datetime -> date

>>> import datetime
>>> datetime.datetime.now().date()
datetime.date(2015, 1, 12)

date -> datetime

>>> datetime.date.today()
datetime.date(2015, 1, 12)
>>> today = datetime.date.today()
>>> datetime.datetime.combine(today, datetime.time())
datetime.datetime(2015, 1, 12, 0, 0)
>>> datetime.datetime.combine(today, datetime.time.min)
datetime.datetime(2015, 1, 12, 0, 0)

datetime <=> timestamp
datetime -> timestamp

>>> now = datetime.datetime.now()
>>> timestamp = time.mktime(now.timetuple())
>>> timestamp
1421077403.0

timestamp -> datetime

>>> datetime.datetime.fromtimestamp(1421077403.0)
datetime.datetime(2015, 1, 12, 23, 43, 23)