python 使用scrapy框架爬取一个图书网站的信息

# -*- coding: utf-8 -*-
import scrapy
from book_project.items import BookItem

class BookInfoSpider(scrapy.Spider):
    name = "bookinfo"#定义爬虫的名字
    allowed_domains = ["allitebooks.com", "amazon.com"]#定义爬取的范围
    start_urls = [
        "http://www.allitebooks.com/security/",
    ]

    def parse(self, response):
        num_pages=int(response.xpath(‘//span[contains(@class,"pages")]/text()‘).extract_first().split()[-2])
        base_url = "http://www.allitebooks.com/security/page/{0}/"
        for page in range(1, num_pages):
            yield scrapy.Request(base_url.format(page), dont_filter=True, callback=self.parse_page)
                #open(‘my.txt‘, ‘wb‘).write(page)

    def parse_page(self, response):
        for sel in response.xpath(‘//div/article‘):
            book_detail_url = sel.xpath(‘div/header/h2/a/@href‘).extract_first()
            yield scrapy.Request(book_detail_url, callback=self.parse_book_info)

    def parse_book_info(self, response):
        title = response.css(‘.single-title‘).xpath(‘text()‘).extract_first()
        isbn = response.xpath(‘//dd[2]/text()‘).extract_first()
        item = BookItem()
        item[‘title‘] = title
        item[‘isbn‘] = isbn
        # yield item
        amazon_search_url = ‘https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=‘ + isbn
        yield scrapy.Request(amazon_search_url, headers={‘User-agent‘: ‘Mozilla/5.0‘}, callback=self.parse_price, meta={ ‘item‘: item })

    def parse_price(self, response):
        item = response.meta[‘item‘]
        item[‘price‘] = response.xpath(‘//span/text()‘).re(r‘\$[0-9]+\.[0-9]{2}?‘)[0]
        yield item