datetime模块中包含3个主要类
- datetime
- timedelta
- timezone
当前时间
from datetime import datetime
now = datetime.now()
now的类型是Class datetime.datetime
指定日期时间
from datetime import datetime
dt = datetime(2016, 10, 19, 14, 13, 00)
datetime构建
class datetime.datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None)
tzinfo指定datetime的时区信息,默认为None,因此这种方式构造的datetime对象为本地时区。
timestamp
timestamp与时区无关，计算机内部存储时间一般存储timestamp，UTC时间确定后可以转换到任意时区。
datetime对象转换成timestamp
from datetime import datetime
dt = datetime(2016, 10, 19, 14, 13, 00)
ts = dt.timestamp()
Python的timestamp是一个浮点数，小数点后表示毫秒数。
timestamp转换成本地时区的datetime对象
from datetime import datetime
ts = 142917200.0
dt = datetime.fromtimestamp(ts)
timestamp转换成UTC标准时区的datetime对象
from datetime import datetime
ts = 142917200.0
dt = datetime.utcfromtimestamp(ts)
str格式的时间
string格式的时间转换成datetime
from datetime import datetime
cday = datetime.strptime('2016-10-19 15:30:00', '%Y-%m-%d %H:%M:%S')
datetime转换成string
from datetime import datetime
now = datetime.now()
str_time = now.strftime('%Y-%m-%d %H:%M:%S')
常用格式化字符的含义
| Directive | Meaning |
|---|---|
| %Y | Year with century as a decimal number |
| %y | Year without century as a decimal number [00,99] |
| %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] |
| %a | Locale’s abbreviated weekday name |
| %A | Locale’s full weekday name |
| %b | Locale’s abbreviated month name |
| %B | Locale’s full month name |
datetime加减
from datetime import datetime, timedelta
now = datetime.now()
dt_new = now + timedelta(hours=1)
本地时间转换为UTC时间
得到一个datetime对象后设置时区属性
from datetime import datetime, timedelta, timezone
now = datetime.now()
tz_utc_8 = timezone(timedelta(hours=8))
now.replace(tzinfo=tz_utc_8)
时区转换
对于一个datetime，强制设置正确时区做为基准时间，通过astimezone()转换时区。