Python时间包datetime的使用

目录

• datetime包的常用功能
• datetime包中的常用方法
• python的常用时间格式化符号

认识datetime包

• 日期与时间的结合体-date and time
• 获取当前时间
• 获取时间间隔
• 将时间对象转成时间字符串
• 将字符串转成时间类型

获取当前时间

• 导入包与模块:

  • from datetime import datetime
  • import datetime

• 使用方法:

  • datetime.now()
  • datetime.datetime.now() (today)

• 例子：返回当前年月日时分秒毫秒的datetime对象

In [1]: import datetime

In [2]: datetime.datetime.now()
Out[2]: datetime.datetime(2021, 8, 20, 21, 26, 31, 333349)

获取时间间隔

• 导入包
  • from datetime import datetime
  • from datetime import timedelta
• 使用方法:
  • timeobj = timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, week=0)
• 例子：返回时间间隔的datetime对象

In [3]: from datetime import datetime

In [4]: from datetime import timedelta

In [6]: before_one_day = timedelta(days=1)

In [7]: yestoday = datetime.now() - before_one_day

In [8]: yestoday
Out[8]: datetime.datetime(2021, 8, 19, 21, 30, 27, 315684)

时间对象转字符串

• 获取时间对象∶
  • from datetime import datetime
  • now = datetime.now()
• 时间转字符串:
  • date str = now.strftime(format)
• 例子：符合时间格式的字符串

In [10]: from datetime import datetime

In [11]: date = datetime.now()

In [12]: str_date = date.strftime('%Y-%m-%d %H:%M:%S')

In [13]: str_date
Out[13]: '2021-08-20 21:39:26'

时间字符串转时间类型

• 获取时间模块:
  • from datetime import datetime
• 时间字符串转时间类型:
  • datetime.strptime(tt, format)
• 参数介绍·
  • tt : 符合时间格式的字符串
  • format : tt时间字符串匹配规则

注意：format和字符串中的格式要一致

In [14]: from datetime import datetime

In [15]: str_date = '2021-08-20 19:12:30'

In [16]: date_obj = datetime.strptime(str_date, '%Y-%m-%d %H:%M:%S')

In [17]: date_obj
Out[17]: datetime.datetime(2021, 8, 20, 19, 12, 30)

时间格式符

实战

#!/usr/bin/python3
# -*- coding: utf-8 -*-
# @Time     : 2021/8/20 21:32
# @Author   : InsaneLoafer
# @File     : package_datetime.py

from datetime import datetime
from datetime import timedelta

now = datetime.now()
print(now, type(now))
now_str = now.strftime('%Y-%m-%d %H:%M:%S')
print(now_str, type(now_str))
now_obj = now.strptime(now_str, '%Y-%m-%d %H:%M:%S')
print('====')
print(now_obj, type(now_obj))

three_days = timedelta(days=3)
after_three_day = now + three_days
print(after_three_day)
print('-------')
after_three_day_str = after_three_day.strftime('%Y/%m/%d %H:%M:%S')
before_three_days = now - three_days
print(before_three_days)

one_hour = timedelta(hours=1)
before_one_hour = now - one_hour
print(before_one_hour)

2021-08-20 21:59:30.253475 <class 'datetime.datetime'>
2021-08-20 21:59:30 <class 'str'>
====
2021-08-20 21:59:30 <class 'datetime.datetime'>
2021-08-23 21:59:30.253475
-------
2021-08-17 21:59:30.253475
2021-08-20 20:59:30.253475

Process finished with exit code 0