练习地址: quotes.toscrape.com/
完成任务
- 创建一个新的 Scrapy Project
- 写一个爬虫来抓取站点和提取数据
- 用命令行导出爬取数据
- 将爬虫更改为递归跟踪链接
- 使用爬虫参数
Creating a project
- 创建项目
scrapy startproject tutorial
- 目录
tutorial/
scrapy.cfg # deploy configuration file
tutorial/ # project's Python module, you'll import your code from here
__init__.py
items.py # project items definition file
middlewares.py # project middlewares file
pipelines.py # project pipelines file
settings.py # project settings file
spiders/ # a directory where you'll later put your spiders
__init__.py
First Spider
- tutorial/spiders/quotes_spider.py
from pathlib import Path
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
def start_requests(self):
urls = [
"https://quotes.toscrape.com/page/1/",
"https://quotes.toscrape.com/page/2/",
]
for url in urls:
yield scrapy.Request(url=url, callback=self.parse)
def parse(self, response):
page = response.url.split("/")[-2]
filename = f"quotes-{page}.html"
Path(filename).write_bytes(response.body)
self.log(f"Saved file {filename}")
Run Spider
scrapy crawl quotes
该命令运行名为"quotes"的爬虫, 返回从域名为: quotes.toscrape.com 的请求
Output
... (omitted for brevity)
2016-12-16 21:24:05 [scrapy.core.engine] INFO: Spider opened
2016-12-16 21:24:05 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2016-12-16 21:24:05 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
2016-12-16 21:24:05 [scrapy.core.engine] DEBUG: Crawled (404) <GET https://quotes.toscrape.com/robots.txt> (referer: None)
2016-12-16 21:24:05 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://quotes.toscrape.com/page/1/> (referer: None)
2016-12-16 21:24:05 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://quotes.toscrape.com/page/2/> (referer: None)
2016-12-16 21:24:05 [quotes] DEBUG: Saved file quotes-1.html
2016-12-16 21:24:05 [quotes] DEBUG: Saved file quotes-2.html
2016-12-16 21:24:05 [scrapy.core.engine] INFO: Closing spider (finished)
...
Shortcut
- 简化 start_requests 方法
from pathlib import Path
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
start_urls = [
"https://quotes.toscrape.com/page/1/",
"https://quotes.toscrape.com/page/2/",
]
def parse(self, response):
page = response.url.split("/")[-2]
filename = f"quotes-{page}.html"
Path(filename).write_bytes(response.body)
Extracting data
- 使用 Scrapy shell
scrapy shell 'https://quotes.toscrape.com/page/1/'
使用引号包裹 urls, 因为特殊符号会导致 urls 失效
Output
[ ... Scrapy log here ... ]
2016-09-19 12:09:27 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://quotes.toscrape.com/page/1/> (referer: None)
[s] Available Scrapy objects:
[s] scrapy scrapy module (contains scrapy.Request, scrapy.Selector, etc)
[s] crawler <scrapy.crawler.Crawler object at 0x7fa91d888c90>
[s] item {}
[s] request <GET https://quotes.toscrape.com/page/1/>
[s] response <200 https://quotes.toscrape.com/page/1/>
[s] settings <scrapy.settings.Settings object at 0x7fa91d888c10>
[s] spider <DefaultSpider 'default' at 0x7fa91c8af990>
[s] Useful shortcuts:
[s] shelp() Shell help (print this help)
[s] fetch(req_or_url) Fetch request (or URL) and update local objects
[s] view(response) View response in a browser
在 shell 内使用 CSS 选择 response object 中的元素
- 获取 title
>>> response.css("title")
[<Selector query='descendant-or-self::title' data='<title>Quotes to Scrape</title>'>]
- 获取 title 的 text
>>> response.css("title::text").getall()
['Quotes to Scrape']
- 获取 title 的 text (去掉list)
>>> response.css("title::text").get()
'Quotes to Scrape'
- 使用 re()
>>> response.css("title::text").re(r"Quotes.*")
['Quotes to Scrape']
>>> response.css("title::text").re(r"Q\w+")
['Quotes']
>>> response.css("title::text").re(r"(\w+) to (\w+)")
['Quotes', 'Scrape']
Use XPath
>>> response.xpath("//title")
[<Selector query='//title' data='<title>Quotes to Scrape</title>'>]
>>> response.xpath("//title/text()").get()
'Quotes to Scrape'
Extracting quotes and author
for quote in response.css("div.quote"):
... text = quote.css("span.text::text").get()
... author = quote.css("small.author::text").get()
... tags = quote.css("div.tags a.tag::text").getall()
... print(dict(text=text, author=author, tags=tags))
...
{'text': '“The world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.”', 'author': 'Albert Einstein', 'tags': ['change', 'deep-thoughts', 'thinking', 'world']}
{'text': '“It is our choices, Harry, that show what we truly are, far more than our abilities.”', 'author': 'J.K. Rowling', 'tags': ['abilities', 'choices']}
...
Extracting data by spider
- create Project
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
start_urls = [
"https://quotes.toscrape.com/page/1/",
"https://quotes.toscrape.com/page/2/",
]
def parse(self, response):
for quote in response.css("div.quote"):
yield {
"text": quote.css("span.text::text").get(),
"author": quote.css("small.author::text").get(),
"tags": quote.css("div.tags a.tag::text").getall(),
}
- Output
2016-09-19 18:57:19 [scrapy.core.scraper] DEBUG: Scraped from <200 https://quotes.toscrape.com/page/1/>
{'tags': ['life', 'love'], 'author': 'André Gide', 'text': '“It is better to be hated for what you are than to be loved for what you are not.”'}
2016-09-19 18:57:19 [scrapy.core.scraper] DEBUG: Scraped from <200 https://quotes.toscrape.com/page/1/>
{'tags': ['edison', 'failure', 'inspirational', 'paraphrased'], 'author': 'Thomas A. Edison', 'text': "“I have not failed. I've just found 10,000 ways that won't work.”"}
Storing the scraped data
command
- json
>>> scrapy crawl quotes -O quotes.json
- jsonl
>>> scrapy crawl quotes -o quotes.jsonl
Following links
- 找到下一页按钮
>>> response.css('li.next a').get()
'<a href="/page/2/">Next <span aria-hidden="true">→</span></a>'
- 获取 href 属性的值
>>> response.css("li.next a::attr(href)").get()
'/page/2/'
- example
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
start_urls = [
"https://quotes.toscrape.com/page/1/",
]
def parse(self, response):
for quote in response.css("div.quote"):
yield {
"text": quote.css("span.text::text").get(),
"author": quote.css("small.author::text").get(),
"tags": quote.css("div.tags a.tag::text").getall(),
}
next_page = response.css("li.next a::attr(href)").get()
if next_page is not None:
next_page = response.urljoin(next_page)
yield scrapy.Request(next_page, callback=self.parse)
A shortcut for creating Requests
- response.follow
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
start_urls = [
"https://quotes.toscrape.com/page/1/",
]
def parse(self, response):
for quote in response.css("div.quote"):
yield {
"text": quote.css("span.text::text").get(),
"author": quote.css("span small::text").get(),
"tags": quote.css("div.tags a.tag::text").getall(),
}
next_page = response.css("li.next a::attr(href)").get()
if next_page is not None:
yield response.follow(next_page, callback=self.parse)
不需要调用 urljoin
- 也可以直接带入循环
for href in response.css("ul.pager a::attr(href)"):
yield response.follow(href, callback=self.parse)
- 如果是 a 元素, 也可以简化如下
for a in response.css("ul.pager a"):
yield response.follow(a, callback=self.parse)
- 多请求
yield from response.follow_all(css="ul.pager a", callback=self.parse)
Using spider arguments
>>> scrapy crawl quotes -O quotes-humor.json -a tag=humor
