python - 如何检查要完成下载 Python3 的文件？

Question

我想弄清楚如何检查下载是否已完成。基本上我希望它等到文件下载完成然后打印:下载完成。

这是我当前的代码以及我想用它做什么:

from  urllib import request

print("Are you sure you want to download the newest file? y/n")
answer = input()

while True:
    if answer == 'y':
        print("Downloading file...")
        downloading = True
        request.urlretrieve("FILE_URL", "FILE_NAME")
    elif answer == 'n':
         exit()
    else:
         print("That is not a valid answer, please answer with y/n.")
         answer = input()

#I need some sort of function here that checks if the file is still being 
#downloaded

when downloading == False:
    print("Download Completed.")

Answer 1

当 urlretrieve 返回时，文件已经下载完成。

请参阅 docs 中的用法示例:

>>> import urllib.request
>>> local_filename, headers = urllib.request.urlretrieve('http://python.org/')
>>> html = open(local_filename)

可以看出，文件在调用 urlretrieve 后立即打开，因为它已经创建并且内容已经写入那里。