第十六章 爬虫scrapy登录与中间件

1. scrapy处理cookie

1. 直接从浏览器复制cookie

scrapy.Requests()中的cookies属于字典，需要转换

 def start_requests(self):
     cookie_str = "GUID=**702477247"
     cookie_dic = {}
     cookie_lst = cookie_str.split("; ")
     for it in cookie_lst:
         if "https://" in it:
             it_cop = it.replace("=","|",1)
             k, v = it_cop.split("|")
             cookie_dic[k.strip()] = v.strip()
         else:
             k,v = it.split("=")
             cookie_dic[k.strip()] = v.strip()
     head = {
         "Referer":"https://user.17k.com/www/bookshelf/",
         "User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
     }

     yield scrapy.Request(
         url=self.start_urls[0],
         headers=head,
         cookies=cookie_dic)

2.登录流程获取cookie

scrapy.FormRequest()可以提交post请求

def start_requests(self):
    url = "https://passport.17k.com/ck/user/login"
    yield scrapy.FormRequest(
        url=url,
        formdata ={
            "loginName":"***",
            "password":"***"
        },
        callback=self.parse
    )

def parse(self, response,**kwargs):
    yield scrapy.Request(
        url=self.start_urls[0],
        callback=self.get_shujia
    )

def get_shujia(self, resp):
    print(resp.text)

2. 中间件

1. DownloaderMiddleware
   ????下载中间件,它是介于引擎和下载器之间，引擎在获取到request对象后,会交给下载器去下载,在这之间我们可以设置下载中间件
2. SpiderMiddleware
   ????爬虫中间件.是处于引擎和spider之间的中间件

class XiaoshuoDownloaderMiddleware:
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader 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_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

    def process_response(self, request, response, spider):
        '''
        :param request:当前的请求
        :param response:请求的响应
        :param spider:发送请求的spider
        :return:
        '''
        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

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

1. 请求中间件

在引擎将请求的信息交给下载器之前，自动的调用该方
param request:当前请求
param spider:发出该请求的spider
注意，process_request返回值是有规定的。

1. 如果返回的None，不做拦截．继续向后面的中间件执行.
2. 如果返回的是Request、后续的中间件将不再执行.将请求重新交给引擎．引擎重新扔给调度器
3. 如果返回的是Response、后续的中间件将不再执行.将响应信息交给引擎．引擎将响应丢给spider，进行数

2. sittings文件中设置UserAgent

# setting文件中打开中间USER_AGENT
# USER_AGENT = "xiaoshuo (+http://www.yourdomain.com)"

• 列表形式创建

# 导包
from xiaoshuo.settings import USER_AGENT_LIST
from random import choice



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
    UA = choice(USER_AGENT_LIST)
    request.headers['User-Agent'] = UA
    return None
# 打开setting文件中的中间件
#DOWNLOADER_MIDDLEWARES = {
#    "xiaoshuo.middlewares.XiaoshuoDownloaderMiddleware": 543,
}

3. 使用中间件配置代理

配置代理的网站:https://www.kuaidaili.com/

免费代理

# 在setting文件中配置proxt列表
PROXY_IP_LIST = [
  "27.154.6.110":"20714",
  "115.219.1.53":"20231"
]
# 导包
from xiaoshuo.settings import PROXY_IP_LIST
from random import choice

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
	IP = choice(PROXY_IP_LIST)
	request.meta['proxy'] = "https://" + ip
    return None

设置隧道道理

# 快代理的网站右scrapy中间件的源码
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
	proxy = "tps138.kdlapi.com:15919"
	request.meta['proxy'] = f"http://{proxy}"
	# 隧道生成的用户名密码
	request.headers ['Proxy-Authorization'] = basic_auth_header('user','pwd')
	request.headers ["Connection"]= "close"

4. 使用selenium获取页面信息

使用selenium登录获取cookie

原来中间件最大优先级是100
我们要想替换掉原来的中间件，可以设置优先级为99

DOWNLOADER_MIDDLEWARES = {
   "xiaoshuo.middlewares.XiaoshuoDownloaderMiddleware": 99,
}
def process_request(self, request, spider):
	#所有的请求都会到我这里.
	#需要进行判断．判断出是否需要用selenium来处理请求
	#开始selenium的操作、返回页面源代码组装的response

新建一个reauest.py文件处理selenium请求

from scrapy import Request

class SeleniumRequest(Request):
	paa
# 自定义selenium请求，继承scrapy中的request、

中间件中判断请求是不是 SeleniumReques请求

# 导包
from scrapy.http.response.html import HtmlResponse
from selenium.webdriver import Chrome

def process_request(self, request, spider):
	#所有的请求都会到我这里.
	#需要进行判断．判断出是否需要用selenium来处理请求
	#开始selenium的操作、返回页面源代码组装的response
	# isinstance(request,SeleniumReques):
	if isinstance(request,SeleniumReques):
		self.web.get(request.url)
		page_source = self.web.page_source
		# 封装一个响应对象
		return HtmlResponse(
			url = request.url,
			status = 200,
			body = page_source,
			request = request,
			encoding = 'utf-8'
		)
	else:
		return None

def spider_opened(self, spider):
    self.web = Chrome()

在中间件中自定义步骤

# 修改from_crawler函数
def from_crawler(cls, crawler):
    # This method is used by Scrapy to create your spiders.
    s = cls()
   	# 						自定义的步骤				执行时间	
    crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
    return s

'''
爬虫执行的时机
engine_started = object()
engine_stopped = object()
spider_opened = object()
spider_idle = object()
spider_closed = object()
spider_error = object()
request_scheduled = object()
request_dropped = object()
request_reached_downloader = object()
request_left_downloader = object()
response_received = object()
response_downloaded = object()
headers_received = object()
bytes_received = object()
item_scraped = object()
item_dropped = object()
item_error = object()
feed_slot_closed = object()
feed_exporter_closed = object()
'''