“键：”是否对缓存的网络映像执行任何操作

Question

from tkinter import *
quiz_amount = IntVar()

def quiz():
    quiz_window = Tk()
    window(quiz_window)
    quiz_window.title('Quiz Grades')
    width = quiz_window.winfo_width()
    height= quiz_window.winfo_height()
    quiz_window.geometry('{}x{}'.format(width, height))
    entry_for_grades = Entry(quiz_window, textvariable=quiz_amount)
    entry_for_grades.pack()
    grade_amount = Button(quiz_window,text='Ok',command=lambda:see_text(quiz_window)).place(x=85,y=60)   
def see_text(window):
    Label(window,text=float(quiz_amount.get())).place(x=85,y=90)

我在某处读到，使用CachedNetworkImage( key: ValueKey(DateTime.now().millisecondsSinceEpoch), imageUrl: url, placeholder: (context, url) => new CircularProgressIndicator(), ), 可以确保始终重新加载您的图像（例如，如果您想使用key:更改图像url。但是在网上和该示例中都可以看到Flutter示例缓存的网络映像的文件夹未指定密钥