爬取知名社区技术文章_article_3

#!/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