用python可以下载网页源码吗

import urllib2

def download(url, num_retries = 5):

    '''

    function: 下载网页源代码，如果遇到 5xx 错误状态，则继续尝试下载，直到下载 num_retries 次为止。

    '''

    print "downloading " , url

    try:

        html = urllib2.urlopen(url).read()

    except urllib2.URLError as e:

        print "download error: " , e.reason

        html = None

        if num_retries > 0:

            if hasattr(e,'code') and 500 <= e.code < 600:

                return download(url, num_retries-1)

    return html