from tkinter import *
from tkinter import filedialog
base = Tk()
# 创建画布
base.geometry('150x150')
# 打开文件的函数
def file_opener():
   input = filedialog.askopenfile(initialdir="/")
   print(input)
   for i in input:
      print(i)
# 按钮标签
x = Button(base, text ='选择一个.txt/.csv文件', command = lambda:file_opener())
x.pack()
mainloop()

<_io.TextIOWrapper name='C:/Users/Pradeep/Documents/welcome.txt' mode='r' encoding='cp1252'>
Hello There !
Welcome to Tutorialspoint!