Scrapy使用笔记

1.创建项目

scrapy startproject tutorial 创建名为tutorial的项目

2.定义Item

Items.py:

import scrapy

class DmozItem(scrapy.Item):
    title = scrapy.Field()
    link = scrapy.Field()
    desc = scrapy.Field()

3.编写爬虫Spider

tutorial/spiders/下创建 dmoz_spider.py:

必须继承scrapy.Spider类；定义 name、start_urls、parse()

import scrapy

class DmozSpider(scrapy.spiders.Spider):
    name = "dmoz"
    allowed_domains = ["dmoz.org"]
    start_urls = [
        "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",
        "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/"
    ]

    def parse(self, response):
        filename = response.url.split("/")[-2]
        with open(filename, 'wb') as f:
            f.write(response.body)

4.爬取数据

首先，进入项目根目录

scrapy crawl dmoz

5.提取Item: Xpath 和 css 选择器selector

for sel in response.xpath('//ul/li'):
    title = sel.xpath('a/text()').extract()
    link = sel.xpath('a/@href').extract()
    desc = sel.xpath('text()').extract()
    print title, link, desc

6.使用Item

from tutorial.items import DmozItem
def parse(self, response):
        for sel in response.xpath('//ul/li'):
            item = TutorialItem()
            item['title'] = sel.xpath('a/text()').extract()
            item['link'] = sel.xpath('a/@href').extract()
            item['desc'] = sel.xpath('text()').extract()
            yield item

7.保存爬取的数据

scrapy crawl dmoz -o items.json