一. 时间的表示类型

py中可能涉及的time有四种类型

  1. time string
  2. datetime tuple(datetime obj)
  3. time tuple(time obj)
  4. timestamp

1. time string

string是最简单的表示time的方式
如如下代码生成的即为string

>>> time.ctime()
'Mon Dec 17 21:02:55 2012'


或者更简单的生成一个字符串

time_string = '2000-01-02 03:04:05'


2. datetime tuple(datetime obj)

datetime tuple是datetime.datetime对象类型

>>> datetime.now()
datetime.datetime(2012, 12, 17, 21, 3, 44, 139715)


3. time tuple(time obj)

time tuple是time.struct_time对象类型

time.struct_time(tm_year=2008, tm_mon=11, tm_mday=10, tm_hour=17, tm_min=53, tm_sec=59, tm_wday=0, tm_yday=315, tm_isdst=-1)


4. timestamp

时间戳类型:自1970年1月1日(00:00:00 GMT)以来的秒数

>>> time.time()
1355749338.05917



二. 类型之间的转换

1. string 转换为其它

初始化:

date_str = "2008-11-10 17:53:59"


1.1 string --> datetime obj

导入:

import datetime
datetime.datetime.strptime(string, format)
>>> dt_obj = datetime.datetime.strptime(date_str, "%Y-%m-%d %H:%M:%S")
>>> dt_obj
datetime.datetime(2008, 11, 10, 17, 53, 59)


1.2 string --> time obj

导入:

import time
time.strptime(string, format)

#time模块有类似datetime中的strptime()函数
>>> date_str = "2008-11-10 17:53:59"
>>> t_obj = time.strptime(date_str, "%Y-%m-%d %H:%M:%S")
>>> t_obj
time.struct_time(tm_year=2008, tm_mon=11, tm_mday=10, tm_hour=17, tm_min=53, tm_sec=59, tm_wday=0, tm_yday=315, tm_isdst=-1)


2. datetime obj转换为其它

datetime obj转换为其它类型,用的都是datetime的函数
初始化:

dt_obj = datetime.datetime(2008, 11, 10, 17, 53, 59)


2.1 dt obj --> string

date_str = dt_obj.strftime("%Y-%m-%d %H:%M:%S")


2.2 dt obj --> time obj

time_tuple = dt_obj.timetuple()


3. time obj转换为其它

初始化:

time_tuple = (2008, 11, 12, 13, 51, 18, 2, 317, 0)


3.1 time obj --> string

date_str = time.strftime("%Y-%m-%d %H:%M:%S", time_tuple)


3.2 time obj --> datetime obj

datetime.datetime(*time_tuple[0:6])


3.3 time obj --> timestamp

ts = time.mktime(time_tuple)


4. timestamp转换为其它

初始化:

timestamp = 1226527167.595983


!!注意以下两种都使用local时区

4.1 timestamp --> dt obj

dt_obj = datetime.fromtimestamp(timestamp)


4.2 timestamp --> time obj

time_tuple = time.localtime(timestamp)


!!以下两种方式和时区相关,比较标准时区时间和本地时区时间

4.3 使用UTC --> dt obj

#本地时区时间
>>> datetime.datetime.fromtimestamp(tm)
datetime.datetime(2012, 12, 17, 23, 39, 58, 401881)
#标准时区时间
>>> datetime.datetime.utcfromtimestamp(tm)
datetime.datetime(2012, 12, 17, 15, 39, 58, 401881)


4.4 使用UTC --> time obj

#本地时区时间
>>> time.localtime(tm)
time.struct_time(tm_year=2012, tm_mon=12, tm_mday=17, tm_hour=23, tm_min=39, tm_sec=58, tm_wday=0, tm_yday=352, tm_isdst=0)
#标准时区时间
>>> time.gmtime(tm)
time.struct_time(tm_year=2012, tm_mon=12, tm_mday=17, tm_hour=15, tm_min=39, tm_sec=58, tm_wday=0, tm_yday=352, tm_isdst=0)