Python项目--Scrapy框架(一)

环境

win8, python3.7, pycharm

正文

1.Scrapy框架的安装

在cmd命令行窗口执行:

pip install Scrapy

即可完成Scrapy框架的安装

2. 创建Scrapy项目

在cmd命令行窗口下切换到想要的目录下, 我这里是C:\Users\Administrator\PycharmProjects\untitled\Tests\Scrapy

执行下面代码, 即可在当前的"Scrapy"目录下生成JianShu项目文件夹.

scrapy startproject JianShu

文件夹结构如下:

items.py: 定义要爬取的项目

middlewares.py: 定义爬取时的中间介质

pipelines.py: 定义数据管道

settings.py: 配置文件

scrapy.cfg: Scrapy部署时的配置文件

3. 创建JianShuSpider

在cmd命令行依次执行以下代码, 即可在"JianShu/spiders"目录下创建JianShuSpider.py文件

cd JianShu
scrapy genspider JianShuSpider JianShuSpider.toscrape.com

4. 定义要爬取的项目

在items.py中确定要爬取的信息: 简书热门专题中的主题, 内容, 文章数, 粉丝数这四个信息

 import scrapy
 from scrapy.item import Item, Field

 class JianshuItem(Item):
     # define the fields for your item here like:
     # name = scrapy.Field()
     title = Field()         #主题
     content  = Field()      #内容
     article = Field()       #文章
     fans = Field()          #粉丝

5. 编写爬虫主程序

简书热门专题采用异步加载, 在NetWork中选择XHR来确定异步加载的url: https://www.jianshu.com/recommendations/collections?page=(1,2,3,4.....)&order_by=hot

在JianShuSpider.py中编写主程序:

 import scrapy
 from scrapy.spiders import CrawlSpider
 from scrapy.selector import Selector
 from JianShu.items import JianshuItem
 from scrapy.http import Request
 class JianShu(CrawlSpider):
     name = 'JianShu'
     allowed_domains = ['JianShuSpider.toscrape.com']
     start_urls = ['https://www.jianshu.com/recommendations/collections?page=1&order_by=hot']
     def parse(self, response):
         item = JianshuItem()
         #对源码进行初始化
         selector = Selector(response)
         #采用xpath进行解析
         infos = selector.xpath('//div[@class="collection-wrap"]')
         for info in infos:
             title = info.xpath('a[1]/h4/text()').extract()[0]
             content = info.xpath('a[1]/p/text()').extract()
             article = info.xpath('div/a/text()').extract()[0]
             fans = info.xpath('div/text()').extract()[0]
             #加入判断, 如果content存在则返回content[0], 否则返回''
             if content:
                 content = content[0]
             else:
                 content = ''
             item['title'] = title
             item['content'] = content
             item['article'] = article
             item['fans'] = fans
             yield item
         #列表生成式, 生成多个url
         urls = ['https://www.jianshu.com/recommendations/collections?page={0}&order_by=hot'.format(str(page)) for page in range(2,37)]
         for url in urls:
             yield Request(url,callback=self.parse)

6. 保存到MongoDB

利用pipelines数据管道将其存储至MongoDB, 在pipelines.py编写:

 import pymongo

 class JianshuPipeline(object):
     def __init__(self):
         '''连接Mongodb'''
         client = pymongo.MongoClient(host='localhost')
         db = client['test']
         jianshu = db["jianshu"]
         self.post = jianshu
     def process_item(self, item, spider):
         '''写入Mongodb'''
         info = dict(item)
         self.post.insert(info)
         return item

7. setting配置

 BOT_NAME = 'JianShu'
 SPIDER_MODULES = ['JianShu.spiders']
 NEWSPIDER_MODULE = 'JianShu.spiders'
 #从网站请求头复制粘贴User-Agent
 USER_AGENT = 'Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'
 ROBOTSTXT_OBEY = True
 #设置等待时间5秒
 DOWNLOAD_DELAY = 5
 #配置项目管道
 ITEM_PIPELINES = {
    'JianShu.pipelines.JianshuPipeline': 300,
 }

8. 新建main.py文件

在JianShu文件目录下新建main.py文件, 编辑如下代码:

 from scrapy import cmdline
 cmdline.execute('scrapy crawl JianShu'.split())

9. 运行main.py文件

在运行之前, 需确保mongodb服务已经启动, 执行结果如下: