from tkinter import *
import tkinter.filedialog
root = Tk()
def xz():
 filename = tkinter.filedialog.askopenfilename()
 if filename != '':
  lb.config(text = "您选择的文件是："+filename);
 else:
  lb.config(text = "您没有选择任何文件");
lb = Label(root,text = '')
lb.pack()
btn = Button(root,text="弹出选择文件对话框",command=xz)
btn.pack()
root.mainloop()

from tkinter import *
import tkinter.filedialog
root = Tk()
def xz():
 filenames = tkinter.filedialog.askopenfilenames()
 if len(filenames) != 0:
  string_filename =""
  for i in range(0,len(filenames)):
   string_filename += str(filenames[i])+"\n"
  lb.config(text = "您选择的文件是："+string_filename)
 else:
  lb.config(text = "您没有选择任何文件");
lb = Label(root,text = '')
lb.pack()
btn = Button(root,text="弹出选择文件对话框",command=xz)
btn.pack()
root.mainloop()