>>> import datetime
string转datetime
>>> import datetime
>>> str = "2016-04-03"
>>> date_time = datetime.datetime.strptime(str,'%Y-%m-%d')
>>> date_time
datetime.datetime(2016, 4, 3, 0, 0)
datetime转string
>>> date_time.strftime('%Y-%m-%d')
'2016-04-03'
datetime转时间戳
>>> time_time = time.mktime(date_time.timetuple())
>>> time_time
1459612800.0
时间戳转string
>>> time.strftime('%Y-%m-%d',time.localtime(time_time))
'2016-04-03'