scrapy spider的几种爬取方式实例代码

本节课介绍了scrapy的爬虫框架，重点说了scrapy组件spider。

spider的几种爬取方式：

1. 爬取1页内容
2. 按照给定列表拼出链接爬取多页
3. 找到‘下一页'标签进行爬取
4. 进入链接，按照链接进行爬取
   

下面分别给出了示例

1.爬取1页内容

#by 寒小阳(hanxiaoyang.ml@gmail.com)

import scrapy


class JulyeduSpider(scrapy.Spider):
  name = "julyedu"
  start_urls = [
    'https://www.julyedu.com/category/index',
  ]

  def parse(self, response):
    for julyedu_class in response.xpath('//div[@class="course_info_box"]'):
      print julyedu_class.xpath('a/h4/text()').extract_first()
      print julyedu_class.xpath('a/p[@class="course-info-tip"][1]/text()').extract_first()
      print julyedu_class.xpath('a/p[@class="course-info-tip"][2]/text()').extract_first()
      print response.urljoin(julyedu_class.xpath('a/img[1]/@src').extract_first())
      print "\n"

      yield {
        'title':julyedu_class.xpath('a/h4/text()').extract_first(),
        'desc': julyedu_class.xpath('a/p[@class="course-info-tip"][1]/text()').extract_first(),
        'time': julyedu_class.xpath('a/p[@class="course-info-tip"][2]/text()').extract_first(),
        'img_url': response.urljoin(julyedu_class.xpath('a/img[1]/@src').extract_first())
      }

2.按照给定列表拼出链接爬取多页

#by 寒小阳(hanxiaoyang.ml@gmail.com)

import scrapy


class CnBlogSpider(scrapy.Spider):
  name = "cnblogs"
  allowed_domains = ["cnblogs.com"]
  start_urls = [
    'http://www.cnblogs.com/pick/#p%s' % p for p in xrange(1, 11)
    ]

  def parse(self, response):
    for article in response.xpath('//div[@class="post_item"]'):
      print article.xpath('div[@class="post_item_body"]/h3/a/text()').extract_first().strip()
      print response.urljoin(article.xpath('div[@class="post_item_body"]/h3/a/@href').extract_first()).strip()
      print article.xpath('div[@class="post_item_body"]/p/text()').extract_first().strip()
      print article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/a/text()').extract_first().strip()
      print response.urljoin(article.xpath('div[@class="post_item_body"]/div/a/@href').extract_first()).strip()
      print article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/span[@class="article_comment"]/a/text()').extract_first().strip()
      print article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/span[@class="article_view"]/a/text()').extract_first().strip()
      print ""

      yield {
        'title': article.xpath('div[@class="post_item_body"]/h3/a/text()').extract_first().strip(),
        'link': response.urljoin(article.xpath('div[@class="post_item_body"]/h3/a/@href').extract_first()).strip(),
        'summary': article.xpath('div[@class="post_item_body"]/p/text()').extract_first().strip(),
        'author': article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/a/text()').extract_first().strip(),
        'author_link': response.urljoin(article.xpath('div[@class="post_item_body"]/div/a/@href').extract_first()).strip(),
        'comment': article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/span[@class="article_comment"]/a/text()').extract_first().strip(),
        'view': article.xpath('div[@class="post_item_body"]/div[@class="post_item_foot"]/span[@class="article_view"]/a/text()').extract_first().strip(),
      }

3.找到‘下一页'标签进行爬取

import scrapy
class QuotesSpider(scrapy.Spider):
  name = "quotes"
  start_urls = [
    'http://quotes.toscrape.com/tag/humor/',
  ]

  def parse(self, response):
    for quote in response.xpath('//div[@class="quote"]'):
      yield {
        'text': quote.xpath('span[@class="text"]/text()').extract_first(),
        'author': quote.xpath('span/small[@class="author"]/text()').extract_first(),
      }

    next_page = response.xpath('//li[@class="next"]/@herf').extract_first()
    if next_page is not None:
      next_page = response.urljoin(next_page)
      yield scrapy.Request(next_page, callback=self.parse)

4.进入链接，按照链接进行爬取

#by 寒小阳(hanxiaoyang.ml@gmail.com)

import scrapy


class QQNewsSpider(scrapy.Spider):
  name = 'qqnews'
  start_urls = ['http://news.qq.com/society_index.shtml']

  def parse(self, response):
    for href in response.xpath('//*[@id="news"]/div/div/div/div/em/a/@href'):
      full_url = response.urljoin(href.extract())
      yield scrapy.Request(full_url, callback=self.parse_question)

  def parse_question(self, response):
    print response.xpath('//div[@class="qq_article"]/div/h1/text()').extract_first()
    print response.xpath('//span[@class="a_time"]/text()').extract_first()
    print response.xpath('//span[@class="a_catalog"]/a/text()').extract_first()
    print "\n".join(response.xpath('//div[@id="Cnt-Main-Article-QQ"]/p[@class="text"]/text()').extract())
    print ""
    yield {
      'title': response.xpath('//div[@class="qq_article"]/div/h1/text()').extract_first(),
      'content': "\n".join(response.xpath('//div[@id="Cnt-Main-Article-QQ"]/p[@class="text"]/text()').extract()),
      'time': response.xpath('//span[@class="a_time"]/text()').extract_first(),
      'cate': response.xpath('//span[@class="a_catalog"]/a/text()').extract_first(),
    }

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