浅谈python中爬虫框架（talonspider）的介绍

1.为什么写这个？

一些简单的页面，无需用比较大的框架来进行爬取，自己纯手写又比较麻烦

因此针对这个需求写了talonspider:

•1.针对单页面的item提取 - 具体介绍点这里
•2.spider模块 - 具体介绍点这里

2.介绍&&使用

2.1.item

这个模块是可以独立使用的，对于一些请求比较简单的网站（比如只需要get请求），单单只用这个模块就可以快速地编写出你想要的爬虫，比如(以下使用python3，python2见examples目录)：

2.1.1.单页面单目标

比如要获取这个网址http://book.qidian.com/info/1004608738 的书籍信息，封面等信息，可直接这样写：

import time
from talonspider import Item, TextField, AttrField
from pprint import pprint

class TestSpider(Item):
  title = TextField(css_select='.book-info>h1>em')
  author = TextField(css_select='a.writer')
  cover = AttrField(css_select='a#bookImg>img', attr='src')

  def tal_title(self, title):
    return title

  def tal_cover(self, cover):
    return 'http:' + cover

if name == 'main':
  item_data = TestSpider.get_item(url='http://book.qidian.com/info/1004608738')
  pprint(item_data)

具体见qidian_details_by_item.py

2.1.1.单页面多目标

比如获取豆瓣250电影首页展示的25部电影，这一个页面有25个目标，可直接这样写：

from talonspider import Item, TextField, AttrField
from pprint import pprint

# 定义继承自item的爬虫类
class DoubanSpider(Item):
  target_item = TextField(css_select='p.item')
  title = TextField(css_select='span.title')
  cover = AttrField(css_select='p.pic>a>img', attr='src')
  abstract = TextField(css_select='span.inq')

  def tal_title(self, title):
    if isinstance(title, str):
      return title
    else:
      return ''.join([i.text.strip().replace('\xa0', '') for i in title])

if name == 'main':
  items_data = DoubanSpider.get_items(url='movie.douban.com/top250')
  result = []
  for item in items_data:
    result.append({
      'title': item.title,
      'cover': item.cover,
      'abstract': item.abstract,
    })
  pprint(result)

具体见douban_page_by_item.py

2.2.spider

当需要爬取有层次的页面时，比如爬取豆瓣250全部电影，这时候spider部分就派上了用场：

# !/usr/bin/env python
from talonspider import Spider, Item, TextField, AttrField, Request
from talonspider.utils import get_random_user_agent


# 定义继承自item的爬虫类
class DoubanItem(Item):
  target_item = TextField(css_select='p.item')
  title = TextField(css_select='span.title')
  cover = AttrField(css_select='p.pic>a>img', attr='src')
  abstract = TextField(css_select='span.inq')

  def tal_title(self, title):
    if isinstance(title, str):
      return title
    else:
      return ''.join([i.text.strip().replace('\xa0', '') for i in title])


class DoubanSpider(Spider):
  # 定义起始url，必须
  start_urls = ['https://movie.douban.com/top250']
  # requests配置
  request_config = {
    'RETRIES': 3,
    'DELAY': 0,
    'TIMEOUT': 20
  }
  # 解析函数 必须有
  def parse(self, html):
    # 将html转化为etree
    etree = self.e_html(html)
    # 提取目标值生成新的url
    pages = [i.get('href') for i in etree.cssselect('.paginator>a')]
    pages.insert(0, '?start=0&filter=')
    headers = {
      "User-Agent": get_random_user_agent()
    }
    for page in pages:
      url = self.start_urls[0] + page
      yield Request(url, request_config=self.request_config, headers=headers, callback=self.parse_item)

  def parse_item(self, html):
    items_data = DoubanItem.get_items(html=html)
    # result = []
    for item in items_data:
      # result.append({
      #   'title': item.title,
      #   'cover': item.cover,
      #   'abstract': item.abstract,
      # })
      # 保存
      with open('douban250.txt', 'a+') as f:
        f.writelines(item.title + '\n')


if name == 'main':
  DoubanSpider.start()

控制台：

/Users/howie/anaconda3/envs/work3/bin/python /Users/howie/Documents/programming/python/git/talonspider/examples/douban_page_by_spider.py
2017-06-07 23:17:30,346 - talonspider - INFO: talonspider started
2017-06-07 23:17:30,693 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250
2017-06-07 23:17:31,074 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=25&filter=
2017-06-07 23:17:31,416 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=50&filter=
2017-06-07 23:17:31,853 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=75&filter=
2017-06-07 23:17:32,523 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=100&filter=
2017-06-07 23:17:33,032 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=125&filter=
2017-06-07 23:17:33,537 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=150&filter=
2017-06-07 23:17:33,990 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=175&filter=
2017-06-07 23:17:34,406 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=200&filter=
2017-06-07 23:17:34,787 - talonspider_requests - INFO: GET a url: https://movie.douban.com/top250?start=225&filter=
2017-06-07 23:17:34,809 - talonspider - INFO: Time usage：0:00:04.462108

Process finished with exit code 0

此时当前目录会生成douban250.txt，具体见douban_page_by_spider.py。

3.说明

学习之作，待完善的地方还有很多，欢迎提意见，项目地址talonspider。

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