python爬虫案列5————scrapy-1

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2024-04-25 帮助1人

1.scrapy

Scrapy是一个为了爬取网站数据，提取结构性数据而编写的应用框架。可以应用在包括数据挖掘，信息处理或存储历史数据等一系列的程序中。

2.scrapy项目的创建以及运行

1.创建scrapy项目：终端输入 scrapy startproject 项目名称
2.项目组成：

spiders
- init.py 自定义的爬虫文件.py ‐‐‐》由我们自己创建，是实现爬虫核心功能的文件
- init.py items.py ‐‐‐》定义数据结构的地方，是一个继承自scrapy.Item的类
middlewares.py ‐‐‐》中间件代理
pipelines.py ‐‐‐》管道文件，里面只有一个类，用于处理下载数据的后续处理默认是300优先级，值越小优先级越高（1‐1000）
settings.py ‐‐‐》配置文件比如：是否遵守robots协议，User‐Agent定义等

3.创建爬虫文件：

创建爬虫文件：
（1）跳转到spiders文件夹 cd 目录名字/目录名字/spiders
（2）scrapy genspider 爬虫名字网页的域名
爬虫文件的基本组成：

继承scrapy.Spider类
- name = ‘百度’ ‐‐‐》运行爬虫文件时使用的名字
- allowed_domains ‐‐‐》爬虫允许的域名，在爬取的时候，如果不是此域名之下的 url，会被过滤掉
- start_urls ‐‐‐》声明了爬虫的起始地址，可以写多个url，一般是一个
- response.text ‐‐‐》响应的是字符串
- response.body ‐‐‐》响应的是二进制文件
- response.xpath()‐》xpath方法的返回值类型是selector列表
- extract() ‐‐‐》提取的是selector对象的是data
- extract_first() ‐‐‐》提取的是selector列表中的第一个数据
- parse(self, response) ‐‐‐》解析数据的回调函数

运行爬虫文件：
scrapy crawl 爬虫名称注意：应在spiders文件夹内执行

4.简单样例

4.1文件结构

学新通

4.2代码

import scrapy
class BaiduSpider(scrapy.Spider):
    # 爬虫的名字  用于运行爬虫的时候 使用的值
    name = '百度'
    # 允许访问的域名
    allowed_domains = ['http://www.百度.com']
    # 起始的url地址  指的是第一次要访问的域名
    # start_urls 是在allowed_domains的前面添加一个http://
    #             在 allowed_domains的后面添加一个/
    start_urls = ['http://www.百度.com/']

    # 是执行了start_urls之后 执行的方法   方法中的response 就是返回的那个对象
    # 相当于 response = urllib.request.urlopen()
    #       response  = requests.get()
    def parse(self, response):
        print('苍茫的天涯是我的爱')

5.简单样例

5.1文件结构

学新通

import scrapy


class CarSpider(scrapy.Spider):
    name = 'car'
    allowed_domains = ['https://car.autohome.com.cn/price/brand-15.html']
    start_urls = ['https://car.autohome.com.cn/price/brand-15.html']#ruguo 结尾是html的话，那么是不需要加上\

    def parse(self, response):
        #//div[@class='main-title']/a/text()
        #//div[@class="main-lever"]//span/span/text()
        name_list = response.xpath('//div[@class="main-title"]/a/text()')
        price_list = response.xpath('//div[@class="main-lever"]//span/span/text()')
        print(name_list)#输出的是一个列表
        '''
        [<Selector xpath='//div[@class="main-title"]/a/text()' data='宝马1系'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马3系'>, <Selector xp/div[@class="main-title"]/a/text()' data='宝马i3'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马5系'>, <Selector xpath='//div[@class="mitle"]/a/text()' data='宝马5系新能源'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马X1'>, <Selector xpath='//div[@class="main-title"]/a data='宝马X2'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马iX3'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马X3'lector xpath='//div[@class="main-title"]/a/text()' data='宝马X5'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马2系'>, <Selector xpath='[@class="main-title"]/a/text()' data='宝马4系'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马i4'>, <Selector xpath='//div[@class="main-"]/a/text()' data='宝马5系(进口)'>, <Selector xpath='//div[@class="main-title"]/a/text()' data='宝马6系GT'>]
        输出的是列表中的每一个data中的值
        宝马1系
宝马3系
宝马i3
宝马5系
宝马5系新能源
宝马X1
宝马X2
宝马iX3
宝马X3
宝马X5
宝马2系
宝马4系
宝马i4
宝马5系(进口)

        '''
        for name in name_list:
            print(name.extract())
        print('============')
        print(price_list.extract_first())#获取得到的是第一个Selector的值的data。
        pass

6.完整样例

6.1 代码结构

学新通

6.2 代码

dang.py

import scrapy
from sccrapy_dangdang_095.items import SccrapyDangdang095Item

class DangSpider(scrapy.Spider):
    name = 'dang'
    # allowed_domains = ['http://e.dangdang.com/list-AQQG-dd_sale-0-1.html']
    # start_urls = ['http://e.dangdang.com/list-AQQG-dd_sale-0-1.html']#ruguo 结尾是html的话，那么是不需要加上\

    allowed_domains = ['category.dangdang.com']
    start_urls = ['http://category.dangdang.com/cp01.01.02.00.00.00.html']

    base_url = "http://category.dangdang.com/pg"
    page = 1

    def parse(self, response):
        #//div[@class="title"]/text()
        #//div[@class="price"]/span/text()

        #pipelines 下载数据
        #items 定义数据结构
        #所有的seletor的对象 都可以再次调用xpath方法
        li_list = response.xpath('//ul[@id="component_59"]/li')

        for li in li_list:
            #里面就有一个东西
            src = li.xpath('.//img/@data-original').extract_first()
            #第一张
            if src:
                src = src
            else:
                src = li.xpath('.//img/@src').extract_first()

            name = li.xpath('.//img/@alt').extract_first()#获取到名字
            price = li.xpath('.//p[@class="price"]/span[1]/text()').extract_first()#获取到p标签中的价格

            book = SccrapyDangdang095Item(src=src, name=name, price=price)

            #huoqu获取一个book就将book交给pipelines
            yield book

        if self.page < 100:
            self.page = self.page   1

            url = self.base_url   str(self.page)   '-cp01.01.02.00.00.00.html'

            #             怎么去调用parse方法
            #             scrapy.Request就是scrpay的get请求
            #             url就是请求地址
            #             callback是你要执行的那个函数  注意不需要加（）
            yield scrapy.Request(url=url, callback=self.parse)

        print('============')

items.py

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

import scrapy


class SccrapyDangdang095Item(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    # tongshu通俗的说就是需要下载的数据都有什么

    #图片
    src = scrapy.Field()
    #名字
    name = scrapy.Field()
    #价格
    price = scrapy.Field()
    pass

pipelines.py

# 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

# 如果想使用管道的话 那么就必须在settings中开启管道
class SccrapyDangdang095Pipeline:

    # 在爬虫文件开始的之前就执行的一个方法
    def open_spider(self,spider):
        self.fp = open('book.json','w',encoding='utf-8')

    # item就是yield后面的book对象
    def process_item(self, item, spider):
        self.fp.write(str(item))
        return item

    #在爬虫文件执行完之后 执行的方法
    def close_spider(self,spider):
        self.fp.close()



import urllib.request
# 多条管道开启
#    (1) 定义管道类
#   （2） 在settings中开启管道
# 'scrapy_dangdang_095.pipelines.DangDangDownloadPipeline':301
class DangDangDownloadPipeline:
    def process_item(self,item,spider):

        url = 'http:'   item.get('src')
        filename = './books/'   item.get('name')   '.jpg'
        urllib.request.urlretrieve(url=url, filename=filename)

        return item

setting.py

# Scrapy settings for sccrapy_dangdang_095 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 = 'sccrapy_dangdang_095'

SPIDER_MODULES = ['sccrapy_dangdang_095.spiders']
NEWSPIDER_MODULE = 'sccrapy_dangdang_095.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'sccrapy_dangdang_095 ( 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 = {
#    'sccrapy_dangdang_095.middlewares.SccrapyDangdang095SpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'sccrapy_dangdang_095.middlewares.SccrapyDangdang095DownloaderMiddleware': 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 = {
#  管道可以有很多个  那么管道是有优先级的  优先级的范围是1到1000   值越小优先级越高
   'sccrapy_dangdang_095.pipelines.SccrapyDangdang095Pipeline': 300,


#    DangDangDownloadPipeline
   'sccrapy_dangdang_095.pipelines.DangDangDownloadPipeline':301
}

# 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'

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python爬虫案列5————scrapy-1

1.scrapy

2.scrapy项目的创建以及运行

3.创建爬虫文件：

4.简单样例

4.1文件结构

4.2代码

5.简单样例

5.1文件结构

6.完整样例

6.1 代码结构

6.2 代码

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