Python-基礎-時間日期處理小結涉及對象1. datetime
2. timestamp
3. time tuple
4. string
5. date

datetime基本操作1. 獲取當前datetime
2. 獲取當天date
3. 獲取明天/前N天
4. 獲取當天開始和結束時間(00:00:00 23:59:59)
5. 獲取兩個datetime的時間差
6. 獲取本周/本月/上月最后一天

關系轉換
關系轉換例子datetime <=> string
datetime <=> timetuple
datetime <=> date
datetime <=> timestamp

原則, 以datetime
為中心, 起點或中轉, 轉化為目標對象, 涵蓋了大多數業務場景中需要的日期轉換處理
步驟:

1. 掌握幾種對象及其關系2. 了解每類對象的基本操作方法3. 通過轉化關系轉化

涉及對象

1. datetime
   import datetime
   now = datetime.datetime.now()
   nowdatetime.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. 獲取當前datetime
   import datetime
   datetime.datetime.now()
   datetime.datetime(2015, 1, 12, 23, 26, 24, 475680)

2. 獲取當天date
   datetime.date.today()
   datetime.date(2015, 1, 12)

3. 獲取明天/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. 獲取當天開始和結束時間(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. 獲取兩個datetime的時間差
   (datetime.datetime(2015,1,13,12,0,0) - datetime.datetime.now()).total_seconds()
   44747.768075

6. 獲取本周/本月/上月最后一天
   本周
   today = datetime.date.today()
   todaydatetime.date(2015, 1, 12)
   sunday = today + datetime.timedelta(6 - today.weekday())
   sundaydatetime.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_daydatetime.date(2015, 1, 31)

獲取上個月的最后一天(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)

關系轉換
幾個關系之間的轉化
Datetime Object / String / timestamp / time tuple

關系轉換例子
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())
timestamp1421077403.0

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