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:UsersAdministratorPycharmProjectsuntitledTestsScrapy

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: