爬虫篇 6 手动请求发送 五大核心组件 请求传参 中间件初识 虎牙全站爬取

- 管道的持久化存储：
　　- 数据解析（爬虫类）
　　- 将解析的数据封装到item类型的对象中（爬虫类）
　　- 将item提交给管道：yield item（爬虫类）
　　- 在官大类的process_item中接收item对象并且进行任意形式的持久化存储操作（管道类）
　　- 在配置文件中开启管道

- 细节：
- 将爬取的数据进行备份？
　　- 一个管道类对应一种平台的持久化存储
- 有多个管道类是否意味着多个管道类都可以接受到爬虫文件提交的item？
　　- 只有优先级最高的管道才可以接受到item，剩下的管道类是需要从优先级最高的管道类中接收item

- 基于Spider父类进行全站数据的爬取
- 全站数据的爬取：将所有页码对应的页面数据进行爬取
- 手动请求的发送（get）：
yield scrapy.Request(url,callback)
- 对yield的总结：
- 向管道提交item的时候：yield item
- 手动请求发送：yield scrapy.Request(url,callback)
- 手动发起post请求：
yield scrapy.FormRequest(url,formdata,callback):formdata是一个字典表示的是请求参数

虎牙全站爬取（多页面）

定义一个

import scrapy
from huyaAll.items import HuyaallItem


class HuyaSpider(scrapy.Spider):
    name = 'huya'
    # allowed_domains = ['www.ccc.com']
    start_urls = ['https://www.huya.com/g/xingxiu']
    url = 'https://www.huya.com/cache.php?m=LiveList&do=getLiveListByPage&gameId=1663&tagAll=0&page=%s'

    def parse(self, response):
        li_list = response.xpath('//*[@id="js-live-list"]/li')
        all_data = []
        for li in li_list:
            title = li.xpath('./a[2]/text()').extract_first()  # 去【】
            author = li.xpath(' ./span/span[1]/i/text()').extract_first()
            hot = li.xpath('./ span / span[ 2] / i[2]/text()').extract_first()
            #     print(title,author,hot)
            #     dic = {
            #         'title':title,
            #         'author':author,
            #         'hot':hot
            #     }
            #     all_data.append(dic)
            # return all_data
            item = HuyaallItem()
            item['title'] = title
            item['author'] = author
            item['hot'] = hot
            yield item  # 提交给管道
            print(1)
        for page in range(2, 5):
            new_url = format(self.url % page)
            print(2)
            yield scrapy.Request(url=new_url, callback=self.parse_other)

    def parse_other(self, response):
        print(3)
        print(response.text)
        # 解析方法没有写

 害！难受

哥们自己解析了一下

        for page in range(2,3):
            new_url = format(self.url % page)

            yield scrapy.Request(url=new_url, callback=self.parse_other, meta={'item': item})

    def parse_other(self, response,):
        item = response.meta['item']
        s = ''
        htmlBody = response.xpath('//text()').extract()
        for aa in htmlBody:
            s = s + str(aa)
        res = json.loads(s)
        res_data = res['data']['datas']
        for i in res_data:
            item['title'] = i['roomName']
            item['author'] = i['nick']
            item['hot'] =i['totalCount']
            yield item

- scrapy五大核心组件
引擎(Scrapy)
　　用来处理整个系统的数据流处理, 触发事务(框架核心)

调度器(Scheduler)
　　用来接受引擎发过来的请求, 压入队列中, 并在引擎再次请求的时候返回. 可以想像成一个URL（抓取网页的网址或者说是链接）的优先队列, 由它来决定下一个要抓取的网址是什么, 同时去除重复的网址

下载器(Downloader)
　　用于下载网页内容, 并将网页内容返回给蜘蛛(Scrapy下载器是建立在twisted这个高效的异步模型上的)

爬虫(Spiders)

　　爬虫是主要干活的, 用于从特定的网页中提取自己需要的信息, 即所谓的实体(Item)。用户也可以从中提取出链接,让Scrapy继续抓取下一个页面
项目管道(Pipeline)
　　负责处理爬虫从网页中抽取的实体，主要的功能是持久化实体、验证实体的有效性、清除不需要的信息。当页面被爬虫解析后，将被发送到项目管道，并经过　　几个特定的次序处理数据。

- scrapy的请求传参
- 作用：实现深度爬取。
- 使用场景：如果使用scrapy爬取的数据没有存在同一张页面中
- 传递item：yield scrapy.Request(url,callback,meta)
- 接收item：response.meta

import scrapy
from moivePro.items import MoiveproItem


class MovieSpider(scrapy.Spider):
    name = 'movie'
    # allowed_domains = ['www.xxx.com']
    start_urls = ['http://www.4567kan.com/index.php/vod/show/class/喜剧/id/1.html']
    url = 'http://www.4567kan.com/index.php/vod/show/class/喜剧/id/1/page/%s.html'
    page = 1

    def parse(self, response):
        print('正在爬取第{}页电影。。。'.format(self.page))

        li_list = response.xpath('/html/body/div[1]/div/div/div/div[2]/ul/li')
        url_h = 'http://www.4567kan.com'
        for li in li_list:
            item = MoiveproItem()
            name = li.xpath('./div/div/h4/a').extract_first()
            item['name'] = name
            # 请求传参：Requset将一个字典{meta=}传递给回调函数
            detail_url = url_h + li.xpath('./div/div/h4/a/@href').extract_first()
            yield scrapy.Request(detail_url, callback=self.parse_other, meta={'item': item})
        if self.page < 5:
            self.page += 1
            new_url = format(self.url % self.page)
            yield scrapy.Request(new_url, callback=self.parse)

    def parse_other(self, response):
        # 接收请求传参的数据（字典）
        item = response.meta['item']
        desc = response.xpath('/html/body/div[1]/div/div/div/div[2]/p[5]/span[3]/text()').extract_first()
        item['desc'] = desc
        yield item

- 提升scrapy爬取数据的效率
　　- 在配置文件中进行相关的配置即可:

增加并发：
　　默认scrapy开启的并发线程为32个，可以适当进行增加。在settings配置文件中修改CONCURRENT_REQUESTS = 100值为100,并发设置成了为100。

降低日志级别：
　　在运行scrapy时，会有大量日志信息的输出，为了减少CPU的使用率。可以设置log输出信息为INFO或者ERROR即可。在配置文件中编写：LOG_LEVEL = 　　‘INFO’

禁止cookie：
　　如果不是真的需要cookie，则在scrapy爬取数据时可以禁止cookie从而减少CPU的使用率，提升爬取效率。在配置文件中编写：COOKIES_ENABLED = False

禁止重试：
　　对失败的HTTP进行重新请求（重试）会减慢爬取速度，因此可以禁止重试。在配置文件中编写：RETRY_ENABLED = False

减少下载超时：
　　如果对一个非常慢的链接进行爬取，减少下载超时可以能让卡住的链接快速被放弃，从而提升效率。在配置文件中进行编写：DOWNLOAD_TIMEOUT = 10 超时时间为10s

- scrapy的中间件
- 爬虫中间件
　　- 下载中间件（***）：处于引擎和下载器之间
　　- 作用：批量拦截所有的请求和响应

- 为什么拦截请求
　　- 篡改请求的头信息（UA伪装）

1、在设置里面打开下载中间键

2、不在设置里面写UA 

3、在middlewares.py中重写 ，class MiddleproDownloaderMiddleware:、

可以创建按一个UA池

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

from scrapy import signals

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

# class MiddleproSpiderMiddleware:
#     # Not all methods need to be defined. If a method is not defined,
#     # scrapy acts as if the spider middleware does not modify the
#     # passed objects.
#
#     @classmethod
#     def from_crawler(cls, crawler):
#         # This method is used by Scrapy to create your spiders.
#         s = cls()
#         crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
#         return s
#
#     def process_spider_input(self, response, spider):
#         # Called for each response that goes through the spider
#         # middleware and into the spider.
#
#         # Should return None or raise an exception.
#         return None
#
#     def process_spider_output(self, response, result, spider):
#         # Called with the results returned from the Spider, after
#         # it has processed the response.
#
#         # Must return an iterable of Request, or item objects.
#         for i in result:
#             yield i
#
#     def process_spider_exception(self, response, exception, spider):
#         # Called when a spider or process_spider_input() method
#         # (from other spider middleware) raises an exception.
#
#         # Should return either None or an iterable of Request or item objects.
#         pass
#
#     def process_start_requests(self, start_requests, spider):
#         # Called with the start requests of the spider, and works
#         # similarly to the process_spider_output() method, except
#         # that it doesn’t have a response associated.
#
#         # Must return only requests (not items).
#         for r in start_requests:
#             yield r
#
#     def spider_opened(self, spider):
#         spider.logger.info('Spider opened: %s' % spider.name)
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:

    # 拦截请求
    def process_request(self, request, spider):
        # 进行UA伪装
        request.headers['User-Agent'] = random.choice(user_agent_list)
        print(request.headers['User-Agent'])
        return None
    # 拦截所有的响应
    def process_response(self, request, response, spider):

        return response

    # 拦截发生异常的请求对象
    def process_exception(self, request, exception, spider):

        pass

    # def spider_opened(self, spider):
    #     spider.logger.info('Spider opened: %s' % spider.name)

　　- 修改请求对应的ip（代理）

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

from scrapy import signals

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

# class MiddleproSpiderMiddleware:
#     # Not all methods need to be defined. If a method is not defined,
#     # scrapy acts as if the spider middleware does not modify the
#     # passed objects.
#
#     @classmethod
#     def from_crawler(cls, crawler):
#         # This method is used by Scrapy to create your spiders.
#         s = cls()
#         crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
#         return s
#
#     def process_spider_input(self, response, spider):
#         # Called for each response that goes through the spider
#         # middleware and into the spider.
#
#         # Should return None or raise an exception.
#         return None
#
#     def process_spider_output(self, response, result, spider):
#         # Called with the results returned from the Spider, after
#         # it has processed the response.
#
#         # Must return an iterable of Request, or item objects.
#         for i in result:
#             yield i
#
#     def process_spider_exception(self, response, exception, spider):
#         # Called when a spider or process_spider_input() method
#         # (from other spider middleware) raises an exception.
#
#         # Should return either None or an iterable of Request or item objects.
#         pass
#
#     def process_start_requests(self, start_requests, spider):
#         # Called with the start requests of the spider, and works
#         # similarly to the process_spider_output() method, except
#         # that it doesn’t have a response associated.
#
#         # Must return only requests (not items).
#         for r in start_requests:
#             yield r
#
#     def spider_opened(self, spider):
#         spider.logger.info('Spider opened: %s' % spider.name)
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:

    # 拦截请求
    def process_request(self, request, spider):
        # 进行UA伪装
        request.headers['User-Agent'] = random.choice(user_agent_list)
        print(request.headers['User-Agent'])

        # 代理
        request.meta['proxy'] = 'http://163.204.94.131:9999'
        print(request.meta['proxy'])
        return None
    # 拦截所有的响应
    def process_response(self, request, response, spider):

        return response

    # 拦截发生异常的请求对象
    def process_exception(self, request, exception, spider):

        pass

    # def spider_opened(self, spider):
    #     spider.logger.info('Spider opened: %s' % spider.name)

- 为什么拦截响应
　　- 篡改响应数据，篡改响应对象
　　- 爬取网易新闻的新闻标题和内容

- selenium在scrapy中的使用流程
- 在爬虫类中定义一个bro的属性，就是实例化的浏览器对象
- 在爬虫类重写父类的一个closed(self,spider)，在方法中关闭bro
- 在中间件中进行浏览器自动化的操作
- 作业：
- 网易新闻
- http://sc.chinaz.com/tupian/xingganmeinvtupian.html网站中的图片数据进行爬取