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: 中的主题, 内容, 文章数, 粉丝数这四个信息

 1 import scrapy
 2 from scrapy.item import item, field
 3 
 4 class jianshuitem(item):
 5     # define the fields for your item here like:
 6     # name = scrapy.field()
 7     title = field()         #主题
 8     content  = field()      #内容
 9     article = field()       #文章
10     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:

 1 import scrapy
 2 from scrapy.spiders import crawlspider
 3 from scrapy.selector import selector
 4 from jianshu.items import jianshuitem
 5 from scrapy.http import request
 6 class jianshu(crawlspider):
 7     name = 'jianshu'
 8     allowed_domains = ['jianshuspider.toscrape.com']
 9     start_urls = ['https://www.jianshu.com/recommendations/collections?page=1&order_by=hot']
10     def parse(self, response):
11         item = jianshuitem()
12         #对源码进行初始化
13         selector = selector(response)
14         #采用xpath进行解析
15         infos = selector.xpath('//div[@class="collection-wrap"]')
16         for info in infos:
17             title = info.xpath('a[1]/h4/text()').extract()[0]
18             content = info.xpath('a[1]/p/text()').extract()
19             article = info.xpath('div/a/text()').extract()[0]
20             fans = info.xpath('div/text()').extract()[0]
21             #加入判断, 如果content存在则返回content[0], 否则返回''
22             if content:
23                 content = content[0]
24             else:
25                 content = ''
26             item['title'] = title
27             item['content'] = content
28             item['article'] = article
29             item['fans'] = fans
30             yield item
31         #列表生成式, 生成多个url
32         urls = ['https://www.jianshu.com/recommendations/collections?page={0}&order_by=hot'.format(str(page)) for page in range(2,37)]
33         for url in urls:
34             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:

 1 import pymongo
 2 
 3 class jianshupipeline(object):
 4     def __init__(self):
 5         '''连接mongodb'''
 6         client = pymongo.mongoclient(host='localhost')
 7         db = client['test']
 8         jianshu = db["jianshu"]
 9         self.post = jianshu
10     def process_item(self, item, spider):
11         '''写入mongodb'''
12         info = dict(item)
13         self.post.insert(info)
14         return item

7. setting配置

 1 bot_name = 'jianshu'
 2 spider_modules = ['jianshu.spiders']
 3 newspider_module = 'jianshu.spiders'
 4 #从网站请求头复制粘贴user-agent
 5 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'
 6 robotstxt_obey = true
 7 #设置等待时间5秒
 8 download_delay = 5
 9 #配置项目管道
10 item_pipelines = {
11    'jianshu.pipelines.jianshupipeline': 300,
12 }

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:

1 from scrapy import cmdline
2 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: