爬虫-scrapy的中间件

其他 2019-06-20 22:09:48 阅读次数: 0

scrapy的中间件

  • 下载中间件

    • 作用:
      • 处于引擎和下载器之间,因此该中间件可以批量拦截整个工程中发起所有的请求和响应
    • 拦截请求可进行的操作
      • 进行代理IP
        • request.meta['proxy'] = 'http://ip:port'
      • 进行UA伪装
        • request.headers['User-Agent'] = 'xxxx'
    • 拦截响应可进行的操作
      • 篡改响应数据(一般不用)
      • 更换响应对象
    • 在scrapy中使用selenium
      • 爬虫类中定义一个bro的属性(selenium实例化的一个浏览器对象)
      • 爬虫类中重写父类的一个方法closed(self,spider),在该方法中关闭浏览器对象
      • 在中间件中的process_response中通过spider参数获取爬虫类中的bro属性
      • 在中间件中编写相关的浏览器自动化的操作获取页面源码数据
      • 将页面源码数据作为新的响应对象的响应数据
      • 将新的响应对象返回

  • 基于crawlSpier的全站数据爬取

    • crawlSpier和Spider之间的关联?
      • crawlSpier是SPider的一个子类
    • 创建一个基于CrawlSpider的爬虫文件
      • scrapy genspider -t crawl xxx www.xxx.com

  • 一个简单的IP端口测试

    • 项目运行文件设置
    import scrapy

class MidSpider(scrapy.Spider):
    name = 'mid'
    # allowed_domains = ['www.xxx.com']
    start_urls = ['http://www.baidu.com/s?wd=ip']

    def parse(self, response):
        page_text = response.text
        with open('./ip.html','w',encoding='utf-8') as fp:
            fp.write(page_text)
    • item中不需要任何操作
    • pipelines文件代码
    class MiddleproPipeline(object):
    def process_item(self, item, spider):
        return item
    • middlewares文件中代码
    rom scrapy import signals
import random
#可被选用的代理IP
PROXY_http = [
    '153.180.102.104:80',
    '195.208.131.189:56055',
]
PROXY_https = [
    '120.83.49.90:9000',
    '95.189.112.214:35508',
]
#UA池的汇总
user_agent_list = [
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 "
        "(KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1",
        "Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 "
        "(KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 "
        "(KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 "
        "(KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6",
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 "
        "(KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 "
        "(KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5",
        "Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 "
        "(KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 "
        "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24",
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 "
        "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24"
]
class MiddleproDownloaderMiddleware(object):

    #拦截正常请求
    def process_request(self, request, spider):
        #UA伪装:UA池,每次都使用随机的UA
        request.headers['User-Agent'] = random.choice(user_agent_list)

        #使用伪装的代理IP访问
        request.meta['proxy'] = 'http://39.137.77.66:8080'
    #拦截所有的响应
    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response
    #拦截发生异常的请求
    def process_exception(self, request, exception, spider):
        #代理ip的设定
        if request.url.split(':')[0] == 'http':
            request.meta['proxy'] = random.choice(PROXY_http)
        else:
            request.meta['proxy'] = random.choice(PROXY_https)

        return request  #将修正之后的请求对象进行重新发送
    • 此时settings文件中需要将中间件打开
    DOWNLOADER_MIDDLEWARES = {
   'middlePro.middlewares.MiddleproDownloaderMiddleware': 543,
}

  • 爬取网易新闻的内容

    • 运行文件内容
    import scrapy

from selenium import webdriver
class WangyiSpider(scrapy.Spider):
    name = 'wangyi'
    # allowed_domains = ['www.xxx.com']
    start_urls = ['https://news.163.com/world/']

    #实例化一个浏览器对象,需要添加chromedriver插件
    bro = webdriver.Chrome(executable_path=r'D:\爬虫\谷歌访问助手\chromedriver.exe')
    def parse(self, response):
        div_list = response.xpath('/html/body/div/div[3]/div[4]/div[1]/div/div/ul/li/div/div')
        for div in div_list:
        #xpath表达式需要跳过body标签,遇到body标签常使用//跳过
            title = div.xpath('.//div[@class="news_title"]//a/text()').extract_first()
            detail_url = div.xpath('.//div[@class="news_title"]//a/@href').extract_first()
            yield scrapy.Request(detail_url,self.parse_detail)
            print(title,detail_url)

    def parse_detail(self,response):
        content = response.xpath('//*[@id="endText"]//text()').extract()
        #使用join将列表数据组成字符串
        content = ''.join(content)
        print(content)
    def closed(self,spider):
        self.bro.quit()
    • items文件不需要操作
    • pipeline文件的操作
    class WangyiproPipeline(object):
    def process_item(self, item, spider):
        return item
    • middleware文件中的操作
    from scrapy import signals

from scrapy.http import HtmlResponse
from time import sleep



class WangyiproDownloaderMiddleware(object):

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None
    #spider表示的就是爬虫类实例化的对象
    def process_response(self, request, response, spider):
        #将不符合需求的响应对象修改成符合需求的
        #body:响应数据
        #如何获取爬虫类中生成的浏览器对象呢?
        if request.url == 'https://news.163.com/world/':
            bro = spider.bro
            bro.get('https://news.163.com/world/')
            sleep(2)
  #这里使用了js自动下滑处理动态加载数据          bro.excute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(1)
            bro.excute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(1)
            bro.excute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(1)
            page_text = bro.page_source

            new_response = HtmlResponse(url=bro.current_url,body=page_text,encoding='utf-8',request=request)

            return new_response
        else:
            return response


    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass
    • 最后在settings文件中加上中间件的配置
    DOWNLOADER_MIDDLEWARES = {
   'wangyiPro.middlewares.WangyiproDownloaderMiddleware': 543,
}

  • crawlspider全站数据爬取案例

    • 执行文件内容
    import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
from sunShinePro.items import SunshineproItem,sunConetent

# http://wz.sun0769.com/index.php/question/questionType?type=4&page=30
class SunSpider(CrawlSpider):
    name = 'sun'
    # allowed_domains = ['www.xxx.com']

    start_urls = ['http://wz.sun0769.com/index.php/question/questionType?type=4&page=']
    #链接提取器
        #作用:根据 指定的规则(allow:正则) 提取页面源码中指定的连接,进行对页面中的页码连接提取
    link = LinkExtractor(allow=r'type=4&page=\d+')
    link_detail = LinkExtractor(allow='question/\d+/\d+\.shtml')
    rules = (
        #规则解析器:将连接提取器提取到的连接对应的页面源码数据 根据指定规则(callback) 进行数据解析
        Rule(link, callback='parse_item', follow=False),
        Rule(link_detail, callback='parse_detail'),
    )
    def parse_detail(self,response):
        content = response.xpath('/html/body/div[9]/table[2]//tr[1]/td/div[2]//text()').extract()
        content = ''.join(content)

        item = sunConetent()
        item['content'] = content

        yield item

    def parse_item(self, response):
        #注意:如果xpath定位的标签中存在tbody,则需要跳过tbody
        tr_list = response.xpath('//*[@id="morelist"]/div/table[2]//tr/td/table//tr')
        for tr in tr_list:
            title = tr.xpath('./td[2]/a[2]/text()').extract_first()
            status = tr.xpath('./td[3]/span/text()').extract_first()
            item = SunshineproItem()
            item['title'] = title
            item['status'] = status

            yield item
    • items文件内容
    import scrapy


class SunshineproItem(scrapy.Item):
    # define the fields for your item here like:
    title = scrapy.Field()
    status = scrapy.Field()
    # pass
class sunConetent(scrapy.Item):
    content = scrapy.Field()
    • pipelines文件内容
    class SunshineproPipeline(object):
    def process_item(self, item, spider):
        if item.__class__.__name__ == 'SunshineproItem':
            print(item['title'], item['status'])

        else:
            print(item['content'])
        return item
    • 此案例未使用中间件配置,因此settings文件中只做之间的配置,并且middleware文件不需要变动

  • 爬取网易新闻中的5个模块内的所有内容

    • 创建一个工程:scrapy startproject wangyiPro
    • cd wangyiPro

    • 创建一个爬虫文件:scrapy genspider wangyi www.xxx.com(指定的url,必须要先CD到项目中,保证爬虫文件在spiders目录中)

    • wangyi文件中内容

    import scrapy
from wangyiPro.items import WangyiproItem
from selenium import webdriver
class WangyiSpider(scrapy.Spider):
    name = 'wangyi'
    # allowed_domains = ['www.xxx.com']
    # 根据起始url解析出五大板块对应的详情页的url
    start_urls = ['https://news.163.com/']
    model_detail_urls = []#五个板块详情页的url

    bro = webdriver.Chrome(executable_path=r'D:\爬虫\谷歌访问助手\chromedriver.exe')
    def parse(self, response):
        #解析出五大板块对应的详情页的url
        model_list = []  #存储的就是五个板块对应的li标签
        indexs = [3,4,6,7,8]
        li_list = response.xpath('//*[@id="index2016_wrap"]/div[1]/div[2]/div[2]/div[2]/div[2]/div/ul/li')

        for index in indexs:
            model_list.append(li_list[index])

        for li in model_list:
            #五个板块对应详情页的url
            detail_url = li.xpath('./a/@href').extract_first()
            self.model_detail_urls.append(detail_url)
            yield scrapy.Request(detail_url,callback=self.parse_detail)
    #解析:新闻标题和新闻详情页的url
    def parse_detail(self,response):
        div_list = response.xpath('/html/body/div/div[3]/div[4]/div[1]/div/div/ul/li/div/div')
        for div in div_list:
            title = div.xpath('.//div[@class="news_title"]/h3/a/text()').extract_first()
            new_detail_url = div.xpath('.//div[@class="news_title"]/h3/a/@href').extract_first()

            item = WangyiproItem()
            item['title'] = title
            #需要通过请求传参将item传递给news_parse
            yield scrapy.Request(new_detail_url,callback=self.news_parse,meta={'item':item})
    #用来解析新闻内容
    def news_parse(self,response):
        content = response.xpath('//*[@id="endText"]//text()').extract()
        content = ''.join(content)

        item = response.meta['item']
        item['content'] = content

        yield item
    def closed(self,spider):
        self.bro.quit()
    • items中定义字段
    import scrapy


class WangyiproItem(scrapy.Item):
    # define the fields for your item here like:
    title = scrapy.Field()
    content = scrapy.Field()
    pass
    • pipelines文件内容
    class WangyiproPipeline(object):
    fp = None
    def open_spider(self,spider):
        self.fp = open('./wangyi.txt','w',encoding='utf-8')
    def process_item(self, item, spider):
        self.fp.write(item['title']+':'+item['content']+'\n')
        return item
    def close_spider(self,spider):
        self.fp.close()
    • middlewares文件内容
    from scrapy.http import HtmlResponse
from time import sleep


class WangyiproDownloaderMiddleware(object):


    def process_request(self, request, spider):

        return None

    # 可以拦截所有的响应对象:该方法拦截5个指定的响应对象且进行替换操作,其他的响应对象不做处理
    def process_response(self, request, response, spider):
        #定位到5个指定的响应对象
        if request.url in spider.model_detail_urls:
            print(request.url)
            bro = spider.bro
            bro.get(request.url)
            sleep(2)
            bro.execute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(2)
            bro.execute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(2)
            bro.execute_script('window.scrollTo(0,document.body.scrollHeight)')
            sleep(2)
            page_text = bro.page_source
            new_response = HtmlResponse(url=request.url,body=page_text,encoding='utf-8',request=request)

            return new_response
        else:
            return response #将原始的响应对象进行返回

    def process_exception(self, request, exception, spider):

        pass
    • 最后在settings文件中做如下配置
    #不遵从爬虫Robots协议
ROBOTSTXT_OBEY = False
#UA伪装
USER_AGENT = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36'
#开启下载中间件
DOWNLOADER_MIDDLEWARES = {
   'wangyiPro.middlewares.WangyiproDownloaderMiddleware': 543,
}
#开启管道
ITEM_PIPELINES = {
   'wangyiPro.pipelines.WangyiproPipeline': 300,
}
#显示打印错误信息
LOG_LEVEL = 'ERROR'

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