电影天堂的种子爬取（数据获取不全面，存在bug望各位指点）

import requests
from lxml import etree
import pymysql
from urllib import parse
class MysqlHelper(object):
    def __init__(self):
        self.db = pymysql.connect(host='127.0.0.1', port=3306, user='root', password='123456', database='py11', charset='utf8')
        self.cursor = self.db.cursor()

    def execute_modify_sql(self,sql, data):
        self.cursor.execute(sql, data)
        self.db.commit()

    def __del__(self):
        self.cursor.close()
        self.db.close()

sql = 'insert into dy(url_list,tr_list) values (%s,%s)'
mc = MysqlHelper()

headers = {
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
    'Accept-Encoding': 'gzip, deflate',
    'Accept-Language': 'zh-CN,zh;q=0.9',
    'Cache-Control': 'max-age=0',
    'Connection': 'keep-alive',
    'Cookie': 'UM_distinctid=1654b8ae4b08db-0313750a9b0b41-9393265-1fa400-1654b8ae4b2679; XLA_CI=73872247efe6cc02697c8a3cacbe04fa; cscpvcouplet4298_fidx=4; CNZZDATA1260535040=665870404-1534569071-%7C1534671676; cscpvrich5041_fidx=3',
    'Host': 'www.dytt8.net',
    'If-Modified-Since': 'Thu, 09 Aug 2018 15:38:45 GMT',
    'If-None-Match': '"8070a9ef72fd41:328"',
    'Upgrade-Insecure-Requests': '1',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36',
}
#主页
for i in range(1,4):
    url = 'http://www.dytt8.net/html/gndy/dyzz/list_23_{}.html'.format(i)

    response = requests.get(url, headers=headers)

    # with open('dytt8.html', 'wb') as f:
    #     f.write(response.content)

    html_ele = etree.HTML(response.text)

    # print(html_ele)

    tr_list = html_ele.xpath('//div[@class = "co_content8"]/ul/td/table')
    # print(tr_list)
    # url_list = parse.urljoin(url, tr_list)
    # print(url_list)
    #详情页
    for tr_ele in tr_list:
        # print(tr_ele)
        tr_ele_a = tr_ele.xpath('./tr[2]/td[2]/b/a/@href')[0]
        # print(tr_ele_a)
        url_list = parse.urljoin(url, tr_ele_a)
        # print(url_list)
        response_a = requests.get(url_list, headers=headers)
        # print(response_a)

        html_ele_a = etree.HTML(response_a.content.decode('gbk'))
        # print(html_ele_a)

        tr_list = html_ele_a.xpath('//div[@class="bd3r"]/div[2]/div[1]/h1/font/text()')

        data = (url_list, tr_list)
        mc.execute_modify_sql(sql, data)