使用scrapy中的items、piplines、settings

2022-05-31 00:03:48 阅读：144 来源： 互联网

标签：en items spider piplines item scrapy html docs

bookstoscrape

 1 import scrapy
 2 from spider_01_books.items import BookItem
 3 
 4 class BookstoscrapeSpider(scrapy.Spider):
 5     """爬虫类，继承spider"""
 6     #爬虫名称--每一个爬虫的唯一标识
 7     name = 'bookstoscrape'
 8     #允许爬爬取的域名
 9     allowed_domains = ['books.toscrape.com']
10     #初始爬取的URL
11     start_urls = ['http://books.toscrape.com/']
12     #解析下载
13     def parse(self, response):
14         #提取数据
15         #每一本书的信息在<article class="product_pod">中，使用xpath()方法找到所有的article元素，并依次迭代
16         for book in response.xpath('//article[@class="product_pod"]'):
17             # #书名信息在article>h3 >a元素的title属性中
18             #创建item对象
19             item = BookItem()
20             #例如：<a href="catalogue/a-light-in-the-attic_1000/index.html" title="A Light in the Attic">A Light in the ...</a>
21             item['name'] = book.xpath('./h3/a/@title').extract_first()
22             # extract_first()：这个方法返回的是一个string字符串，是list数组里面的第一个字符串。
23             #书价信息在article><div class="product_price">的text中，例如：<p class="price_color">£51.77</p>
24             item['price']= book.xpath('./div[2]/p[1]/text()').extract_first()[1:]
25             #书的评级在article>p 元素的class属性中。例如：<p class="star-rating Three">
26             item['rate'] = book.xpath('./p/@class').extract_first().split(" ")[1]
27 
28             #返回单个图书对象
29             yield item
30         #提取下一页的链接
31         #下一页的url在li.next >a 元素的href属性中
32         #例如：<li class="next"><a href="catalogue/page-2.html">next</a></li>
33         next_url= response.xpath('//li[@class="next"]/a/@href').extract_first()
34 
35         #判断
36         if next_url:
37             #如果找到下一页的URl，则得到绝对路径，构造新的request对象
38             next_url = response.urljoin(next_url)
39             #返回新的request对象
40             yield scrapy.Request(next_url,callback=self.parse)

items：

# Define here the models for your scraped items
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/items.html

import scrapy


class BookItem(scrapy.Item):
    # define the fields for your item here like:
    #可以设置自己想要的格式，设置的名称和bookstoscrape中名字对应
    name = scrapy.Field()

    price = scrapy.Field()
    rate = scrapy.Field()

piplines处理：

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://docs.scrapy.org/en/latest/topics/item-pipeline.html


# useful for handling different item types with a single interface
from itemadapter import ItemAdapter


class PriceConverterPipeline(object):
    """实现英镑转人民币"""

    # 英镑兑换人民币汇率 1英镑=8.7091人民币
    exchange_rate = 8.7091

    def process_item(self, item, spider):
        """处理传入的item,最后返回"""

        # 提取item的price 字段（如￡53.74）
        # 去掉前面英镑符号￡，转换为float类型，乘以汇率
        price = float(item['price'][1:]) * self.exchange_rate
        # 保留2 位小数，赋值回item的price字段
        item['price'] = '￥%.2f' % price
        # 必须返回item
        return item

settings 设置：

# Scrapy settings for spider_01_books project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://docs.scrapy.org/en/latest/topics/settings.html
#     https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://docs.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'spider_01_books'

SPIDER_MODULES = ['spider_01_books.spiders']
NEWSPIDER_MODULE = 'spider_01_books.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'spider_01_books (+http://www.yourdomain.com)'

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://docs.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
#DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
#}

# Enable or disable spider middlewares
# See https://docs.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'spider_01_books.middlewares.Spider01BooksSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'spider_01_books.middlewares.Spider01BooksDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See https://docs.scrapy.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See https://docs.scrapy.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   'spider_01_books.pipelines.PriceConverterPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

标签：en,items,spider,piplines,item,scrapy,html,docs
来源： https://www.cnblogs.com/anhao-world/p/16328834.html

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使用scrapy中的items、piplines、settings