def download_big_file_with_wget(url, target_file_name):

    """

        使用wget下载大文件

        Note: 需要系统安装wget

    """

    import os

    import subprocess

    download_process = subprocess.Popen(["wget", "-c", "-O", target_file_name, "'{}'".format(url)])

    download_process.wait()

    if not os.path.exists(target_file_name):

        raise Exception("fail to download file from {}".format(url))

def download_big_file(url, target_file_name):

    """

        使用python核心库下载大文件

        ref: https://*.com/questions/1517616/stream-large-binary-files-with-urllib2-to-file

    """

    import sys

    if sys.version_info > (2, 7):

        # Python 3

        from urllib.request import urlopen

    else:

        # Python 2

        from urllib2 import urlopen

    response = urlopen(url)

    chunk = 16 * 1024

    with open(target_file_name, 'wb') as f:

        while True:

            chunk = response.read(chunk)

            if not chunk:

                break

            f.write(chunk)