深入了解python的tkinter实现简单登录

import tkinter as tk
from tkinter import messagebox  # import this to fix messagebox error
import pickle
username = ''
# 登录界面
def welcome():
    def usr_login():
        usr_name = var_usr_name.get()
        usr_pwd = var_usr_pwd.get()
        try:
            with open('usrs_info.pickle', 'rb') as usr_file:
                usrs_info = pickle.load(usr_file)
                usr_file.close()
        except FileNotFoundError:
            with open('usrs_info.pickle', 'wb') as usr_file:
                usrs_info = {'admin': 'admin'}
                pickle.dump(usrs_info, usr_file)
                usr_file.close()
        if usr_name in usrs_info:
            if usr_pwd == usrs_info[usr_name]:
                tk.messagebox.showinfo(title='Welcome', message='How are you? ' + usr_name)
                # 进入主页
                global username
                username= usr_name
                print(username)
                window.destroy()
                index_page()
            else:
                tk.messagebox.showerror(message='Error, your password is wrong, try again.')
        else:
            is_sign_up = tk.messagebox.askyesno('Welcome', 'You have not signed up yet. Sign up today?')
            if is_sign_up:
                usr_sign_up()
    window = tk.Tk()
    window.title('Welcome to the login page!')
    window.geometry('450x300')
    # welcome image
    canvas = tk.Canvas(window, height=200, width=500)
    image_file = tk.PhotoImage(file='welcome.gif')
    image = canvas.create_image(0, 0, anchor='nw', image=image_file)
    canvas.pack(side='top')
    # user information
    tk.Label(window, text='User name: ').place(x=50, y=150)
    tk.Label(window, text='Password: ').place(x=50, y=190)
    var_usr_name = tk.StringVar()
    entry_usr_name = tk.Entry(window, textvariable=var_usr_name)
    entry_usr_name.place(x=160, y=150)
    var_usr_pwd = tk.StringVar()
    entry_usr_pwd = tk.Entry(window, textvariable=var_usr_pwd, show='*')
    entry_usr_pwd.place(x=160, y=190)
    # login and sign up button
    btn_login = tk.Button(window, text='Login', command=usr_login)
    btn_login.place(x=170, y=230)
    btn_sign_up = tk.Button(window, text='Sign up', command=usr_sign_up)
    btn_sign_up.place(x=270, y=230)
    window.mainloop()
# 个人信息页面
def index_page():
    global username
    index_window = tk.Tk()
    index_window.title('请选择你要进行的操作')
    index_window.geometry('300x200')
    tk.Label(index_window,text="你好!"+username).place(x=50,y=50)
    # 修改个人信息
    def change_personal_info():
        # 新窗口
        change_info__window = tk.Toplevel()
        change_info__window.title('修改个人信息')
        change_info__window.geometry('400x300')
        # 修改个人信息点击页面
        def change_info_click():
            name = new_name.get()
            psw = new_password.get()
            conpsw = new_password_confirm.get()
            with open('usrs_info.pickle', 'rb') as f:
                usrs_info = pickle.load(f)
                f.close()
            if conpsw!= psw:
                tk.messagebox.showerror(title='Error', message='两次密码不一致请重新输入！')
            else:
                if name in usrs_info:
                    tk.messagebox.showerror(title='Error', message='用户名已存在，请重新换一个新用户名')
                else:
                    # 创建新
                    usrs_info.pop(username)
                    usrs_info[name] = psw
                    with open('usrs_info.pickle', 'wb') as file:
                        pickle.dump(usrs_info, file)
                        f.close()
                    tk.messagebox.showinfo(title='修改成功', message='修改成功！')
                    change_info__window.destroy()
                    tk.messagebox.showinfo(title='请重新登录！', message='请重新登录！')
                    index_window.destroy()
                    welcome()
        # 修改用户名变量
        new_name = tk.StringVar()
        tk.Label(change_info__window, text="用户名：").place(x=50, y=50)
        new_name_entry = tk.Entry(change_info__window, show=None, textvariable=new_name).place(x=120, y=50)
        # 修改新密码变量
        new_password = tk.StringVar()
        tk.Label(change_info__window, text='密码:').place(x=50, y=80)
        new_password_entry = tk.Entry(change_info__window, show="*", textvariable=new_password).place(x=120, y=80)
        # 修改新确认密码变量
        new_password_confirm = tk.StringVar()
        tk.Label(change_info__window, text="确认密码：").place(x=50, y=110)
        new_password_confirm_entry = tk.Entry(change_info__window, show="*", textvariable=new_password_confirm).place(x=120,
                                                                                                 y=110)
        # 修改信息按钮绑定
        sign_window_button = tk.Button(change_info__window, text='确认', command=change_info_click).place(x=150, y=140)
    # 修改个人信息按钮绑定
    change_info_button = tk.Button(index_window,text='修改个人信息',command=change_personal_info).place(x=100,y=100)
# 注册页面
def usr_sign_up():
    sign_up_window = tk.Toplevel()
    sign_up_window.title('注册')
    sign_up_window.geometry('400x200')
    # 注册点击事件
    def sign_up_hit():
        name = new_name.get()
        psw = new_password.get()
        conpsw = new_password_confirm.get()
        with open('usrs_info.pickle', 'rb') as usr_file:
            usrs_info = pickle.load(usr_file)
        if psw!=conpsw:
            tk.messagebox.showerror(title='Error', message='两次密码不一致请重新输入！')
        else:
            if name in usrs_info:
                tk.messagebox.showerror(title='Error', message='用户名已存在')
            else:
                # 创建新
                usrs_info[name] = psw
                with open('usrs_info.pickle', 'wb') as f:
                    pickle.dump(usrs_info,f)
                tk.messagebox.showinfo(title='注册成功', message='注册成功！')
                sign_up_window.destroy()
    # 注册名变量
    new_name = tk.StringVar()
    tk.Label(sign_up_window,text="注册名：").place(x=50,y=50)
    new_name_entry = tk.Entry(sign_up_window,show=None,textvariable=new_name).place(x=120,y=50)
    # 注册密码变量
    new_password = tk.StringVar()
    tk.Label(sign_up_window,text='密码:').place(x=50,y=80)
    new_password_entry = tk.Entry(sign_up_window,show="*",textvariable=new_password).place(x=120,y=80)
    # 注册确认密码变量
    new_password_confirm= tk.StringVar()
    tk.Label(sign_up_window,text="确认密码：").place(x=50,y=110)
    new_password_confirm_entry = tk.Entry(sign_up_window,show="*",textvariable=new_password_confirm).place(x=120,y=110)
    # 注册按钮和点击事件绑定
    sign_window_button = tk.Button(sign_up_window,text='注册',command=sign_up_hit).place(x=150,y=140)
welcome()