python之time模块

import time
时间戳时间：从1970到现在的秒数，time.time()
>>> time.time()
1500964794.3408804

格式化字符串：20170627 21:30:45

元祖：struct_time共九个元素，结构化时间元祖
>>> time.localtime()
time.struct_time(tm_year=2017, tm_mon=7, tm_mday=25, tm_hour=14, tm_min=40, tm_sec=6, tm_wday=1, tm_yday=206, tm_isdst=0)

取出年份：
>>> x = time.localtime()
>>> x
time.struct_time(tm_year=2017, tm_mon=7, tm_mday=25, tm_hour=15, tm_min=23, tm_sec=57, tm_wday=1, tm_yday=206, tm_isdst=0)
>>> x.tm_year
2017

>>> time.gmtime()
time.struct_time(tm_year=2017, tm_mon=7, tm_mday=25, tm_hour=7, tm_min=12, tm_sec=15, tm_wday=1, tm_yday=206, tm_isdst=0)

将结构化元祖时间转化为时间戳：
>>> x = time.localtime()
>>> x
time.struct_time(tm_year=2017, tm_mon=7, tm_mday=25, tm_hour=14, tm_min=44, tm_sec=59, tm_wday=1, tm_yday=206, tm_isdst=0)
>>> time.mktime(x)
1500965099.0

将结构化元祖时间转化为格式化字符串时间：
>>> time.strftime("%Y-%m-%d %H:%M:%S", x)
'2017-07-25 14:44:59'

字符串格式化时间格式：format
　　strftime(...)

    strftime(format[, tuple]) -> string

    Convert a time tuple to a string according to a format specification.
    See the library reference manual for formatting codes. When the time tuple
    is not present, current time as returned by localtime() is used.

    Commonly used format codes:

    %Y  Year with century as a decimal number.
    %m  Month as a decimal number [01,12].
    %d  Day of the month as a decimal number [01,31].
    %H  Hour (24-hour clock) as a decimal number [00,23].
    %M  Minute as a decimal number [00,59].
    %S  Second as a decimal number [00,61].
    %z  Time zone offset from UTC.
    %a  Locale's abbreviated weekday name.
    %A  Locale's full weekday name.
    %b  Locale's abbreviated month name.
    %B  Locale's full month name.
    %c  Locale's appropriate date and time representation.

将格式化字符串时间转化为结构化元祖时间：
strptime(...)
    strptime(string, format) -> struct_time
>>> time.strptime('2017-07-25 14:44:59',"%Y-%m-%d %H:%M:%S")
time.struct_time(tm_year=2017, tm_mon=7, tm_mday=25, tm_hour=14, tm_min=44, tm_sec=59, tm_wday=1, tm_yday=206, tm_isdst=-1)

将结构化元祖时间转化为字符串：
asctime(...)
    asctime([tuple]) -> string

    Convert a time tuple to a string, e.g. 'Sat Jun 06 16:26:11 1998'.
    When the time tuple is not present, current time as returned by localtime()
    is used.

>>> time.asctime(x)
'Tue Jul 25 14:44:59 2017'

将时间戳转化为string：

>>> time.ctime(time.time())

'Tue Jul 25 15:16:11 2017'

>>> time.timezone
-28800             ---->相隔8个小时，这个是秒为单位

>>> time.altzone
-32400             -----》夏令营相隔时间

import datetime
>>> datetime.datetime.now()                  获取当前时间：
datetime.datetime(2017, 7, 25, 15, 17, 30, 899516)
>>> print(datetime.datetime.now())         格式化字符串时间
2017-07-25 15:17:59.255676

获取三天后的时间：

>>> print(datetime.datetime.now() + datetime.timedelta(3))
2017-07-28 15:20:18.179573

获取三天前的时间：

>>> print(datetime.datetime.now() + datetime.timedelta(-3))
2017-07-22 15:21:25.385973

获取当前时间后三个小时：

>>> print(datetime.datetime.now() + datetime.timedelta(hours=3))
2017-07-25 18:22:05.528957

获取当前时间后30分钟：

>>> print(datetime.datetime.now() + datetime.timedelta(minutes=30))
2017-07-25 15:52:52.346930