时间
time模块
time.time()
>>> import time # 导入time模块
>>> time.time() # 返回UTC时间(从1970.1.1到现在的秒数)
1499435147.90761
time.ctime() 接收一个以秒为单位的实际，然后转换成本地时间的字符串表示
>>> time.ctime() #
'Fri Jul 7 21:46:06 2017'
>>> time.ctime(time.time())
'Fri Jul 7 21:47:18 2017'
格式化时间输出
strftime()
>>> from time import strftime,gmtime
>>> strftime('%Y-%m-%d %H:%M:%S')
'2017-07-07 21:49:47'
gtime() 函数将一个时间戳转换为UTC时区（0时区）的struct_time，可选的参数sec表示从1970-1-1以来的秒数。其默认值为time.time()
>>> strftime('%Y-%m-%d %H:%M:%S',gmtime()) #
'2017-07-07 13:50:18'
应用1:格式化当前时间，并以字符串的形式输出
>>> import time
>>> create_time = str(time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(time.time())))
>>> create_time
'2017-08-29 16:56:36'
datetime模块
>>> from datetime import datetime
>>> datetime.now().strftime('%Y-%m-%d %H:%M:%S')
'2016-07-21 19:49:15'
>>> datetime.now().isoformat()
'2016-07-21T19:56:46.744893'
>>> str(datetime.now())
'2016-07-21 19:48:37.436886'
python计算明天的日期
from datetime import datetime, timedelta
now = datetime.now()
aDay = timedelta(days=1)
now = now + aDay
print now.strftime('%Y-%m-%d')
python计算上周时间
from datetime import datetime
from datetime import timedelta
now = datetime.now()
aWeek = timedelta(weeks=-1)
now = now + aWeek
print now.strftime('%Y-%m-%d')
使用timedelta可以很方便的在日期上做天days，小时hour，分钟，秒，毫秒，微妙的时间计算，如果要计算月份则需要另外的办法
计算上个月的月份
import time
last_month = time.localtime()[1]-1 or 12
print last_month
timedelta实现日期相减
from datetime import timedelta, datetime
import time
d1 = datetime.now()
time.sleep(10)
eclipseTimes = datetime.now() - d1
print eclipseTimes.total_seconds() # 转换成miao