这是一个简易版的万年历，目的实现的功能是显示所选中的年份和月份一个月中每个日期所对应的星期数（默认显示的是当天日期），比如选择2023年6月，你可以看到六月的7、14、21、28日是周三（在按钮中选择完年、月后需要按“更新”按钮才可以实现界面的转换），万年历还有拓展功能（显示所选年月日的农历号），需要的可以在评论区留言。

运行结果：  

 程序代码：

from tkinter import *
import time

class Calendar:
    def __init__(self):
        self.vYear = StringVar()
        self.vMonth = StringVar()
        self.vDay = StringVar()
        self.vNongLi = StringVar()

    def leap_year(self,year):
        #判断是否为闰年
        if (year %400 == 0) or ((year % 4 == 0) and (year % 100 != 0)):
            return True
        else:
            return False
    def year_days(self,year,month):  #计算本月天数
        if month in (1,3,5,7,8,10,12):
            return 31
        elif month in (4,6,9,11):
            return 30
        else:
            if self.leap_year(year)==True:
                return 29
            else:
                return 28

    def get_total_days(self,year,month,day):
        total_days=0
        for m in range(1800,year):
            if self.leap_year(m)==True:
                total_days+=366
            else:
                total_days+=365
        for i in range(1,month):
            total_days+=self.year_days(year,i)
        return total_days

    def calcFirstDayOfMonth(self,year,month,day):
        #返回当月1日是星期几，由1800.01.01是星期三推算
        return(self.get_total_days(year,month,day)+3)%7


    def createMonth(self,master):
            #创建日历
        for i in range(6):
            for j in range(7):
                Label(master,text='').grid(row = i + 2,column = j)

    #更新日历
    def updateDate(self):
        #得到当前选择的日期
        year = int(self.vYear.get())
        month = int(self.vMonth.get())
        day = int(self.vDay.get())
        fd = self.calcFirstDayOfMonth(year,month,1)
        print(fd)
        #fd=2
        for i in range(6):
            for j in range(7):
                #返回 grid 中 (i +2,j)位置的组件
                root.grid_slaves(i +2,j)[0]['text'] = ''
        #计算本月的天数
        days=self.year_days(year,month)
        for i in range(1,days + 1):
            root.grid_slaves(int((i + fd - 1)//7 + 2),(i + fd -1)%7)[0]['text'] = str(i)

    def drawHeader(self,master):
        '''添加日历头'''
        #得到当前的日期，设置为默认值
        now = time.localtime(time.time())
        col_idx = 0

        #创建年份组件
        self.vYear = StringVar()
        self.vYear.set(now[0])
        Label(master,text = '年').grid(row = 0,column = col_idx);col_idx += 1
        #设置年份可选菜单OptionMenu项，OptionMenu功能与combox相似
        omYear = OptionMenu(master,self.vYear,*tuple(range(1900,2051)))
        omYear.grid(row = 0,column = col_idx);col_idx += 1

        #创建月份组件
        self.vMonth.set(now[1])
        Label(master,text = '月').grid(row = 0,column = col_idx);col_idx += 1
        #设置月份可选菜单OptionMenu项
        omMonth = OptionMenu(master,self.vMonth,*tuple(range(1,13)))
        omMonth.grid(row = 0,column = col_idx);col_idx += 1

        #创建日组件
        self.vDay.set(now[2])
        Label(master,text = '日').grid(row = 0,column = col_idx);col_idx +=1

        #设置日可选菜单OptionMenu项
        omDay = OptionMenu(master,self.vDay,*tuple(range(1,32)))
        omDay.grid(row = 0,column = col_idx);col_idx += 1

        #创建更新按钮
        btUpdate=Button(master,text = '更新日历',command = self.updateDate)
        btUpdate.grid(row = 0,column = col_idx);col_idx += 1


        #打印星期标签
        weeks = ['周日','周一','周二','周三','周四','周五','周六']
        for week in weeks:
            Label(master,text = week).grid(row = 1,column = weeks.index(week))


root = Tk()
root.title("万年历")
AppCal=Calendar()
AppCal.drawHeader(root)
AppCal.createMonth(root)
AppCal.updateDate()
root.mainloop()