python中日期转字符串/字符串转日期

此处使用的是python的标准库：datetime

先要引用：

from datetime import datetime, timedelta

日期转字符串：

def date2str(datetime1:datetime, strformat:str=None):
    """
    日期转字符串
    """
    try:
        if strformat is None or strformat == "":
            return datetime1.strftime('%Y-%m-%d %H:%M:%S')
        else:
            return datetime1.strftime(strformat)
    except BaseException as ex:
        exstr = "无法转换成str"
        raise ex

使用方式：

datetime3 = datetime.now()
datetime3fm = "%Y-%m-%d"
datetime3str = date2str(datetime3, datetime3fm)

字符串转日期：

def str2date(datetimestr:str, strpattern:str=None):
    """
    字符串转日期
    """
    try:
        if strpattern is None or strpattern == "":
            return datetime.strptime(datetimestr, '%Y-%m-%d %H:%M:%S')
        else:
            return datetime.strptime(datetimestr, strpattern)
    except BaseException as ex:
        exstr = "格式不匹配，无法转换成datetime"
        raise ex

使用方式：

datetime4str = "2022-10-22 10:20"
datetime4pattern = "%Y-%m-%d %H:%M"
datetime4 = str2date(datetime4str, datetime4pattern)

日期的加减计算：

def date_calculate(datetime1:datetime, adddays:int):
    """
    字符串时间的日期加减
    """
    try:
        return datetime1 - timedelta(days=-adddays)
    except BaseException as ex:
        exstr = "计算出错"
        raise ex

使用方式：

datetime1 = datetime.now()
datetime2 = date_calculate(datetime1, -1)

自定义日期：

def getnewDate(year:int=None, month:int=None, day:int=None, hour:int=None, minute:int=None, second:int=None, microsecond:int=None):
    """
    当前时间基础上自定义日期
    """
    try:
        timenow = datetime.now()
        timenow = timenow if year is None else timenow.replace(year=year)
        timenow = timenow if month is None else timenow.replace(month=month)
        timenow = timenow if day is None else timenow.replace(day=day)
        timenow = timenow if hour is None else timenow.replace(hour=hour)
        timenow = timenow if minute is None else timenow.replace(minute=minute)
        timenow = timenow if second is None else timenow.replace(second=second)
        timenow = timenow if microsecond is None else timenow.replace(microsecond=microsecond)
        return timenow
    except BaseException as ex:
        exstr = "获取出错"
        raise ex

使用方式：

datetime1 = getnewDate(year=2001, hour=10)

如果需要对上述代码修改，容易被忽视的一点是：

字符串转日期，使用的是：strptime

日期转字符串，使用的是：strftime

注意两个方法是不一样的！