爬取知名社区技术文章_article_3

时间：2021-02-04 16:21:05

爬虫主逻辑处理，获取字段，获取主url和子url

#!/usr/bin/python3

# -*- coding: utf-8 -*-

import scrapy

from scrapy.http import Request

from urllib import parse

from JobBole.items import JobboleItem, ArticleItemLoader

class ExampleSpider(scrapy.Spider):

    name = 'jobbole'

    # allowed_domains = ['example.com']

    # 起始url

    start_urls = ['http://blog.jobbole.com/all-posts/']

    def parse(self, response):

        # 获取主页面所以有效详情页面url，图片url，下一页url

        home_all_node = response.css('.post.floated-thumb .post-thumb a')

        # 获取节点，循环出每个单张图片和单个url交个下载器和子url处理

        for home_node in home_all_node:

            img_url = home_node.css('img::attr(src)').extract_first('')

            cont_url = home_node.css('::attr(href)').extract_first('')

            # yield 提供异步方法，parser 进行域名拼接，meta进行传值

            yield Request(url=parse.urljoin(response.url, cont_url),

                          meta={'img_url': img_url},

                          callback=self.analysie_go)

        # 提取下一页并下载

        next_page_url = response.css('.next.page-numbers::attr(href)').extract_first('')

        if next_page_url:

            yield Request(url=parse.urljoin(response.url, next_page_url), callback=self.parse)

    def analysie_go(self, response):

        # 解析详情页面获取所需其他字段的值

        img_url = response.meta.get('img_url', '0')

        load_item = ArticleItemLoader(item=JobboleItem(), response=response)

        load_item.add_value('img_url', img_url)

        load_item.add_value('cont_url', response.url)

        load_item.add_value('cont_id', response.url)

        load_item.add_css('title', '.entry-header h1::text')

        load_item.add_css('publish_time', '.entry-meta-hide-on-mobile::text')

        load_item.add_xpath('cont', '//div[@class="entry"]//text()')

        load_item.add_css('link_num', '.vote-post-up h10::text')

        load_item.add_css('collection_num', '.bookmark-btn::text')

        load_item.add_css('comment_num', '.post-adds a span::text')

        article_items = load_item.load_item()

        # 把获取的字段交给items

        yield article_items

　　

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