python 爬虫简单的demo

'''
@author :Eric-chen
@contact:809512722@qq.com
@time   :2018/1/3 17:55
@desc   :通过爬取http://movie.douban.com/top250/得到豆瓣Top 250的电影，并输出到文件movies.txt
'''
import codecs

import requests
from bs4 import BeautifulSoup

DOWNLOAD_URL = 'http://movie.douban.com/top250/'

def download_page(url):
    return requests.get(url).content

def parse_html(html):
    soup = BeautifulSoup(html,"lxml")
    movie_list_soup = soup.find('ol', attrs={'class': 'grid_view'})

    movie_name_list = []

    for movie_li in movie_list_soup.find_all('li'):
        detail = movie_li.find('div', attrs={'class': 'hd'})
        movie_name = detail.find('span', attrs={'class': 'title'}).getText()

        movie_name_list.append(movie_name)

    next_page = soup.find('span', attrs={'class': 'next'}).find('a')
    if next_page:
        return movie_name_list, DOWNLOAD_URL + next_page['href']
    return movie_name_list, None

def main():
    url = DOWNLOAD_URL

    with codecs.open('movies.txt', 'wb', encoding='utf-8') as fp:
        while url:
            html = download_page(url)
            movies, url = parse_html(html)
            fp.write(u'{movies}\n'.format(movies='\n'.join(movies)))

if __name__ == '__main__':
    main()