from urllib.request import urlretrieve
import sys
import os

prev_reported_download_percent = None

# 首先定義下載 hook，作為 urllib.request.urlretrive 的關鍵字引數
def download_hook(count, block_size, total_size):
    """ 介面是寫死的 """
    global prev_reported_download_percent
    percent = int(count*block_size*100/total_size)
    if
 
 prev_reported_download_percent != percent:
        if percent % 5 == 0:
            sys.stdout.write('%s%%' % percent)
            sys.stdout.flush()
        else:
            sys.stdout.write('.')
            sys.stdout.flush()
        prev_reported_download_percent = percent

def maybe_download(filename, force=False)
 
:
    """ force 表示是否強制下載 """
    if force or not os.path.exists(filename):
        print('Attempting to download')
        filename, _ = urlretrieve(url+filename, filename, reporthook=download_hook)
            # url+filename：表示檔案的 url 地址，
            # filename 則為儲存到本地時的檔名
        print('\nDownload completed!'
 
)
    # statinfo = os.stat(filename)
    return filename

比如對於 http://ufldl.stanford.edu/housenumbers/ 網站下的 train.tar.gz/test.tar.gz兩檔案，客戶端的呼叫方式為：

url = 'http://ufldl.stanford.edu/housenumbers/'
train_filename = maybe_download('train.tar.gz')
test_filename = maybe_download('test.tar.gz')