def downloadPage2(url, req_num=10, charset='utf-8', user_agent=None):
    """
    下載網頁資訊,user-Agent的設定
    處理了500-600的錯誤
    限制了錯誤處理的上限次數
    網頁的編碼設定
    :param url: 請求的url連線
    :return: 返回值
    """
    if not user_agent:
        user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64)\
            AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36'
    headers = {'User-Agent': user_agent}
    req = request.Request(url, headers=headers)
    try:
        response = request.urlopen(req)
        with open('test.html', 'wb') as f:
            f.write(response.read())
    except error.HTTPError as e:
        # 伺服器錯誤
        print(e.code)
        html = None
        if req_num > 0:
            if hasattr(e, 'code') and 500 <= e.code <= 600:
                time.sleep(random.randint(5, 11))
                downloadPage2(url, req_num-1)
    except error.URLError:
        print("url error")
        html = None
    return html


if __name__ == '__main__':
    url = 'http://www.sina.com.cnn'
    req = {
        'charset': 'utf-8',
        'req_num': 5,
    }
    print(downloadPage2(url,**req))
    re = redis.Redis()