爬虫系列---Scrapy框架学习

项目的需求需要爬虫某网的商品信息，自己通过Requests,BeautifulSoup等编写了一个spider，把抓取的数据存到数据库里面。

跑起来的感觉速度有点慢，尤其是进入详情页面抓取信息的时候，小白入门，也不知道应该咋个整，反正就是跟着学嘛。

网上的爬虫框架还是挺多的，现在打算学习spcrapy重新写。

下面是记录官方文档的一些学习notes.

scrapy的环境是在anaconda里面搞得，所以子啊pycharm里面的 preject interpreter  选择anaconda下面的python.exe.

很多时候自己老是要忘记设置这个，会导致很多包都import不进来，，因为我很多包都是通过anaconda环境装的。

下面是给的第一个测试例子

class QuotesSpider(scrapy.Spider):
    name = "quotes"
    start_urls = [
        'http://quotes.toscrape.com/tag/humor/',
    ]

    def parse(self, response):
        for quote in response.css('div.quote'):
            yield {
                'text': quote.css('span.text::text').extract_first(),
                'author': quote.xpath('span/small/text()').extract_first(),
            }

        next_page = response.css('li.next a::attr("href")').extract_first()
        if next_page is not None:
            yield response.follow(next_page, self.parse)

在anaconda 的prompt里面输入命令

scrapy runspider quote_spider.py -o quote.json

注意要在文件所在的路径下面哦

运行成功后，会生成一个quote.json的文件

[
{"text": "u201cThe person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid.u201d", "author": "Jane Austen"},
{"text": "u201cA day without sunshine is like, you know, night.u201d", "author": "Steve Martin"},
{"text": "u201cAnyone who thinks sitting in church can make you a Christian must also think that sitting in a garage can make you a car.u201d", "author": "Garrison Keillor"},
{"text": "u201cBeauty is in the eye of the beholder and it may be necessary from time to time to give a stupid or misinformed beholder a black eye.u201d", "author": "Jim Henson"},
{"text": "u201cAll you need is love. But a little chocolate now and then doesn't hurt.u201d", "author": "Charles M. Schulz"},
{"text": "u201cRemember, we're madly in love, so it's all right to kiss me anytime you feel like it.u201d", "author": "Suzanne Collins"},
{"text": "u201cSome people never go crazy. What truly horrible lives they must lead.u201d", "author": "Charles Bukowski"},
{"text": "u201cThe trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it.u201d", "author": "Terry Pratchett"},
{"text": "u201cThink left and think right and think low and think high. Oh, the thinks you can think up if only you try!u201d", "author": "Dr. Seuss"},
{"text": "u201cThe reason I talk to myself is because Iu2019m the only one whose answers I accept.u201d", "author": "George Carlin"},
{"text": "u201cI am free of all prejudice. I hate everyone equally. u201d", "author": "W.C. Fields"},
{"text": "u201cA lady's imagination is very rapid; it jumps from admiration to love, from love to matrimony in a moment.u201d", "author": "Jane Austen"}
]

当你执行scrapy runspider quote_spider.py -o quote.json这条命令的时候，Scrapy会在这个文件里面去look for Spider的定义，找到后用scrapy的crawler engine运行。

通过向start_urls 属性中定义的URL发送请求，并调用默认回调方法parse，将响应对象作为参数传递，从而开始爬网。在parse回调中，我们使用CSS Selector循环引用元素，产生一个带有提取的引用文本和作者的Python字典，查找指向下一页的链接，并使用与parse回调相同的方法安排另一个请求