Scrapy(python爬虫框架)入门笔记

本文章仅作为个人笔记

Scrpy官网

Scrpy官方文档

Scrpy中文文档

个人ScrapyDemo项目地址

python环境安装
  • win下安装:
    • python:下载python安装包直接安装即可
    • pip: easy_install pip
  • mac下安装:
    • python:mac下自带python2.7
    • pip: easy_install pip
  • centos7下安装:
    • python:centos7下自带python2.7
    • pip: easy_install pip
scrapy 安装
pip install Scrapy
创建项目
scrapy startproject 
创建爬虫
scrapy genspider  
在文件夹根目录创建 requirements.txt文件并加入需要的组件,例如:
Scrapy==1.5.0
beautifulsoup4==4.6.0
requests==2.18.4
项目环境搭建
pip install -r requirements.txt
运行单个爬虫
scrapy crawl 
运行多个爬虫(Scrapy本身并不支持命令行直接运行多个Spiders,创建一个新的python文件加入如下内容运行此python文件便可)(需按需更改)
# -*- coding: utf-8 -*-
import sys
    from scrapy.crawler import CrawlerProcess
from scrapy.utils.project import get_project_settings
from ScrapyDemo.spiders.news_estadao import EstadaoSpider
from ScrapyDemo.spiders.news_gazetaesportiva import DemoSpider
from ScrapyDemo.spiders.news_megacurioso import MegacuriosoSpider

if sys.getdefaultencoding != 'utf-8':
    reload(sys)
    sys.setdefaultencoding('utf-8')

process = CrawlerProcess(get_project_settings())
process.crawl(EstadaoSpider)
process.crawl(DemoSpider)
process.crawl(MegacuriosoSpider)
process.start()
启用pipelines用于处理结果
  • 打开settings.py文件在ITEM_PIPELINES选项下加入peline并赋值,0-1000,数字越小越优先
输出单个spider运行结果到文件
scrapy crawl demo -o /path/to/demo.json
多个spider的结果混合处理:
  • 上面的运行多个爬虫脚本并不能将多个spider的结果混合处理
  • 因为业务需要,只可退而求其次
    • 思路:借助commands库运行linux命令顺序运行并输出结果到文件,最后读取文件内容解析为对象进行混合处理

    • 代码(需按需更改):

      #!/usr/bin/env python
      # encoding: utf-8
      import commands
      
      def test():
        result = []
        try:
            commands.getoutput("echo '' > /path/to/megacurioso.json") #清空上次运行结果
            commands.getoutput("scrapy crawl demo -o /path/to/demo.json") # 运行结果并输出
            result = json.loads(commands.getoutput("cat /path/to/megacurioso.json")) # 获取运行结果
        except:
            print "Get megacurioso error."
        return result
      
解决结果爬虫信息乱码问题:
  • 在有乱码问题python文件顶部加入如下代码:

    if sys.getdefaultencoding != 'utf-8':
      reload(sys)
      sys.setdefaultencoding('utf-8')
    
爬虫示例,也可以使用文顶给出的github链接:
  • item示例(items.py):

    # -*- coding: utf-8 -*-
    
    # Define here the models for your scraped items
    #
    # See documentation in:
    # https://doc.scrapy.org/en/latest/topics/items.html
    
    import scrapy
    
    
    class ScrapydemoItem(scrapy.Item):
        title = scrapy.Field()
        imageUrl = scrapy.Field()
        des = scrapy.Field()
        source = scrapy.Field()
        actionUrl = scrapy.Field()
        contentType = scrapy.Field()
        itemType = scrapy.Field()
        createTime = scrapy.Field()
        country = scrapy.Field()
        headUrl = scrapy.Field()
        pass
    
  • pipelines示例(pipelines.py):

    # -*- coding: utf-8 -*-
    
    # Define your item pipelines here
    #
    # Don't forget to add your pipeline to the ITEM_PIPELINES setting
    # See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
    from ScrapyDemo.items import ScrapydemoItem
    import json
    
    
    class ScrapydemoPipeline(object):
        DATA_LIST_NEWS = []
    
        def open_spider(self, spider):
            DATA_LIST_NEWS = []
            print 'Spider start.'
    
        def process_item(self, item, spider):
            if isinstance(item, ScrapydemoItem):
                self.DATA_LIST_NEWS.append(dict(item))
            return item
    
        def close_spider(self, spider):
            print json.dumps(self.DATA_LIST_NEWS)
            print 'Spider end.'
    
  • spider示例(demo.py):

        # -*- coding: utf-8 -*-
        import scrapy
        from ScrapyDemo.items import ScrapydemoItem
    
    
        class DemoSpider(scrapy.Spider):
            name = 'news_gazetaesportiva'
            allowed_domains = ['www.gazetaesportiva.com']
            start_urls = ['https://www.gazetaesportiva.com/noticias/']
            headers = {
                'accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
                'accept-language': 'zh-CN,zh;q=0.9,en-US;q=0.8,en;q=0.7',
                'cache-control': 'max-age=0',
                'upgrade-insecure-requests': '1',
                'User-agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36'
            }
    
            def parse(self, response):
                print('Start parse.')
                for element in response.xpath('//article'):
                    title = element.xpath(".//h3[@class='entry-title no-margin']/a/text()").extract_first()
                    imageUrl = [element.xpath(".//img[@class='medias-object wp-post-image']/@src").extract_first()]
                    des = element.xpath(".//div[@class='entry-content space']/text()").extract_first()
                    source = 'gazeta'
                    actionUrl = element.xpath(".//a[@class='blog-image']/@href").extract_first()
                    contentType = ''
                    itemType = ''
                    createTime = element.xpath(".//small[@class='updated']/text()").extract_first()
                    country = 'PZ'
                    headUrl = ''
                    if title is not None and title != "" and actionUrl is not None and actionUrl != "" and imageUrl is not None and imageUrl != "":
                        item = ScrapydemoItem()
                        item['title'] = title
                        item['imageUrl'] = imageUrl
                        item['des'] = des
                        item['source'] = source
                        item['actionUrl'] = actionUrl
                        item['contentType'] = contentType
                        item['itemType'] = itemType
                        item['createTime'] = createTime
                        item['country'] = country
                        item['headUrl'] = headUrl
                        yield item
                print('End parse.')
    
  • 代码个人理解:

    • settings可配置公共配置及配置pipelines对spiders结果进行汇总,例如(后面的数值越大优先级越低,取值0-1000):

      ITEM_PIPELINES = {
          'DemoScrapy.pipelines.ScrapydemoPipeline': 300,
      }
      
    • 配置pipelines后命令行运行spiders是会先运行open_spider方法,然后每个结果解析时运行process_item方法,最后spider结束时运行close_spider方法

    • items文件是用来配置描述结果对象的

    • spiders文件夹里根据命令行创建的spiders文件配置需要抓取的数据的网页及需要伪装的请求头参数等,抓取数据后数据结果进入 parse方法进行解析,可使用xpath进行解析。xpath的具体使用可参考前文给出的链接,个人进行数据抓取前使用chrom定位标签,复制源码后根据规则找到标签位置最后进行规则匹配,因为每次数据规则匹配不可能一次性完成,建议使用debug功能来进行匹配,最后一次性完成规则书写。

  • pycharm下debug spiders:

    • 打开pycharm后如果遇到部分插件无法安装的情况可使用虚拟环境:


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    • debug运行scrapy:


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      • 运行到断点后右击选择 Evaluate Expresion


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        如此便可随意运行代码查看执行结果

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