【python】常用的日期和时间操作

#-*- coding: utf-8 -*-
import datetime

#给定日期向后N天的日期
def dateadd_day(days):
  d1 = datetime.datetime.now()
  d3 = d1 + datetime.timedelta(days)
  return d3

#昨天
def getYesterday():
  today = datetime.date.today()
  oneday = datetime.timedelta(days=1)
  yesterday = today - oneday
  return yesterday

#今天
def getToday():
  return datetime.date.today()

#获取给定参数的前几天的日期，返回一个list
def getDaysBefore(num):
  today = datetime.date.today()
  oneday = datetime.timedelta(days=1)
  li = []
  for i in range(0, num):
    #今天减一天，一天一天减
    today = today - oneday
    #把日期转换成字符串
    li.append(datetostr(today))
  return li

#将字符串转换成datetime类型
def strtodatetime(datestr, format):
  return datetime.datetime.strptime(datestr, format)

#时间转换成字符串,格式为2015-02-02
def datetostr(date):
  return str(date)[0:10]

#时间转换成字符串,格式为2015-02-02
def datetostr_secod(date):
  return str(date)[0:19]

#两个日期相隔多少天，例：2015-2-04和2015-3-1
def datediff(beginDate, endDate):
  format = "%Y-%m-%d"
  bd = strtodatetime(beginDate, format)
  ed = strtodatetime(endDate, format)
  oneday = datetime.timedelta(days=1)
  count = 0
  while bd != ed:
    ed = ed - oneday
    count += 1
  return count

#两个日期之间相差的秒
def datediff_seconds(beginDate, endDate):
  format = "%Y-%m-%d %H:%M:%S"
  if " " not in beginDate or ':' not in beginDate:
    bformat = "%Y-%m-%d"
  else:
    bformat = format
  if " " not in endDate or ':' not in endDate:
    eformat = "%Y-%m-%d"
  else:
    eformat = format
  starttime = strtodatetime(beginDate, bformat)
  endtime = strtodatetime(endDate, eformat)
  ret = endtime - starttime
  return ret.days * 86400 + ret.seconds

#获取两个时间段的所有时间,返回list
def getDays(beginDate, endDate):
  format = "%Y-%m-%d"
  begin = strtodatetime(beginDate, format)
  oneday = datetime.timedelta(days=1)
  num = datediff(beginDate, endDate) + 1
  li = []
  for i in range(0, num):
    li.append(datetostr(begin))
    begin = begin + oneday
  return li

#获取当前年份 是一个字符串
def getYear(date=datetime.date.today()):
  return str(date)[0:4]

#获取当前月份 是一个字符串
def getMonth(date=datetime.date.today()):
  return str(date)[5:7]

#获取当前天 是一个字符串
def getDay(date=datetime.date.today()):
  return str(date)[8:10]

#获取当前小时 是一个字符串
def getHour(date=datetime.datetime.now()):
  return str(date)[11:13]

#获取当前分钟 是一个字符串
def getMinute(date=datetime.datetime.now()):
  return str(date)[14:16]

#获取当前秒 是一个字符串
def getSecond(date=datetime.datetime.now()):
  return str(date)[17:19]

def getNow():
  return datetime.datetime.now()

print dateadd_day(10)
#2015-02-14 16:41:13.275000

print getYesterday()
#2015-02-03

print getToday()
#2015-02-04

print getDaysBefore(3)
#['2015-02-03', '2015-02-02', '2015-02-01']

print datediff('2015-2-01', '2015-10-05')
#246

print datediff_seconds('2015-02-04', '2015-02-05')
#86400

print datediff_seconds('2015-02-04 22:00:00', '2015-02-05')
#7200

print getDays('2015-2-03', '2015-2-05')
#['2015-02-03', '2015-02-04', '2015-02-05']

print datetostr_secod(getNow())
#2015-02-04 16:46:47

print str(getYear(dateadd_day(-50))) + '-'\
  + getMonth() + '-'\
  + getDay() + ' '\
  + getHour() + ':'\
  + getMinute() + ':'\
  + getSecond()
#2014-02-04 16:59:04

print getNow()