本文利用Python计算今天日期、明天日期、和昨天日期的相关方法，及获取当前日期是星期几。
python编程操作日期时间主要用到的python模块是datetime和time这2个模块
获取星期几from datetime import datetime, date
dayOfWeek = datetime.now().weekday()
print(dayOfWeek)
dayOfWeek = datetime.today().weekday()
print(dayOfWeek)
注意：datetime类的weekday()方法可以获得datetime是星期几，注意weekday()返回的是0~6，是星期一到星期日。
python获取今日日期import datetime
today = datetime.date.today()
print(today)
输出：2019-06-25
python获取昨日日期import datetime
today = datetime.date.today()
zuotian = today- datetime.timedelta(days=1)
print(zuotian)
获取明天日期import datetime
today = datetime.date.today()
tomorrow = today + datetime.timedelta(days=1)
print(tomorrow)
获取后天日期import datetime
today = datetime.date.today()
tomorrow = today + datetime.timedelta(days=2)
print(tomorrow)
小结：不管是往前计算还是往后计算，直接在今日日期上进行天数的相加减