import datetime
import time
#string转datetime
>>>str = '2012-11-19'
>>>date_time = datetime.datetime.strptime(str,'%Y-%m-%d')
>>>date_time
datetime.datetime(2012,11,19,0,0)
#datetime转string
>>>date_time.strftime('%Y-%m-%d')
'2012-11-19'
#datetime转时间戳
>>>time_time = time.mktime(date_time.timetuple())
>>>time_time
1353254400.0
#时间戳转string
>>>time.strftime('%Y-%m-%d',time.localtime(time_time))
'2012-11-19'
#date转datetime
>>>date = datetime.date.today()
>>>date
>>>datetime.date(2012,11,19)
>>>datetime.datetime.strptime(str(date),'%Y-%m-%d') #将date转换为str,在由str转换为datetime
>>>datetime.datetime(2012,11,19,0,0)