对于scrapy请参数，会经常用到，不过没有深究

今天我就来探索下scrapy请求时所携带的3个重要参数headers, cookies, meta

原生参数

首先新建myscrapy项目，新建my_spider爬虫

通过访问：http://httpbin.org/get 来测试请求参数

将爬虫运行起来

# -*- coding: utf-8 -*-from scrapy import Spider, Request
import loggingclass MySpider(Spider):name = 'my_spider'allowed_domains = ['httpbin.org']start_urls = ['http://httpbin.org/get']def parse(self, response):self.write_to_file("*" * 40)self.write_to_file("response text: %s" % response.text)self.write_to_file("response headers: %s" % response.headers)self.write_to_file("response meta: %s" % response.meta)self.write_to_file("request headers: %s" % response.request.headers)self.write_to_file("request cookies: %s" % response.request.cookies)self.write_to_file("request meta: %s" % response.request.meta)def write_to_file(self, words):with open("logging.log", "a") as f:f.write(words)if __name__ == '__main__':from scrapy import cmdlinecmdline.execute("scrapy crawl my_spider".split())

保存到文件中的信息如下：

response text:
{"args":{},"headers":{"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","Accept-Encoding":"gzip,deflate","Accept-Language":"en","Connection":"close","Host":"httpbin.org","User-Agent":"Scrapy/1.5.1 (+https://scrapy.org)"},"origin":"223.72.90.254","url":"http://httpbin.org/get"
}response headers:
{b'Server': [b'gunicorn/19.8.1'], b'Date': [b'Sun, 22 Jul 2018 10:03:15 GMT'], b'Content-Type': [b'application/json'], b'Access-Control-Allow-Origin': [b'*'], b'Access-Control-Allow-Credentials': [b'true'], b'Via': [b'1.1 vegur']
}response meta:
{'download_timeout': 180.0, 'download_slot': 'httpbin.org', 'download_latency': 0.5500118732452393
}request headers:
{b'Accept': [b'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'], b'Accept-Language': [b'en'], b'User-Agent': [b'Scrapy/1.5.1 (+https://scrapy.org)'], b'Accept-Encoding': [b'gzip,deflate']
}request cookies:
{}request meta:
{'download_timeout': 180.0, 'download_slot': 'httpbin.org', 'download_latency': 0.5500118732452393
}

headers

按照如下路径，打开scrapy的default_settings文件

from scrapy.settings import default_settings

发现是这么写的

USER_AGENT = 'Scrapy/%s (+https://scrapy.org)' % import_module('scrapy').__version__DEFAULT_REQUEST_HEADERS = {'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8','Accept-Language': 'en',
}

修改下请求头，看服务器返回的信息

# -*- coding: utf-8 -*-from scrapy import Spider, Request
import loggingclass MySpider(Spider):name = 'my_spider'allowed_domains = ['httpbin.org']start_urls = ['http://httpbin.org/get',]def start_requests(self):for url in self.start_urls:yield Request(url, headers={"User-Agent": "Chrome"})def parse(self, response):logging.debug("*" * 40)logging.debug("response text: %s" % response.text)logging.debug("response headers: %s" % response.headers)logging.debug("request headers: %s" % response.request.headers)if __name__ == '__main__':from scrapy import cmdlinecmdline.execute("scrapy crawl my_spider".split())

输出如下

response text:
{"args":{},"headers":{"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","Accept-Encoding":"gzip,deflate","Accept-Language":"en","Connection":"close","Host":"httpbin.org","User-Agent":"Chrome"},"origin":"122.71.64.121","url":"http://httpbin.org/get"
}response headers:
{b'Server': [b'gunicorn/19.8.1'], b'Date': [b'Sun, 22 Jul 2018 10:29:26 GMT'], b'Content-Type': [b'application/json'], b'Access-Control-Allow-Origin': [b'*'], b'Access-Control-Allow-Credentials': [b'true'], b'Via': [b'1.1 vegur']
}request headers:
{b'User-Agent': [b'Chrome'], b'Accept': [b'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'], b'Accept-Language': [b'en'], b'Accept-Encoding': [b'gzip,deflate']
}

看到 request 和服务器接收到并返回的的 headers（User-Agent）变化了，说明已经把默认的User-Agent修改了

看到default_settings中默认使用了中间件UserAgentMiddleware

'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware': 500,

源码如下


class UserAgentMiddleware(object):"""This middleware allows spiders to override the user_agent"""def __init__(self, user_agent='Scrapy'):self.user_agent = user_agent@classmethoddef from_crawler(cls, crawler):o = cls(crawler.settings['USER_AGENT'])crawler.signals.connect(o.spider_opened, signal=signals.spider_opened)return odef spider_opened(self, spider):self.user_agent = getattr(spider, 'user_agent', self.user_agent)def process_request(self, request, spider):if self.user_agent:request.headers.setdefault(b'User-Agent', self.user_agent)

仔细阅读源码，发现无非就是对User-Agent读取和设置操作，仿照源码写自己的中间件

这里使用fake_useragent库来随机获取请求头，详情可参看：
https://blog.csdn.net/mouday/article/details/80476409

middlewares.py 编写自己的中间件

from fake_useragent import UserAgentclass UserAgentMiddleware(object):def process_request(self, request, spider):ua = UserAgent()user_agent = ua.chromerequest.headers.setdefault(b'User-Agent', user_agent)

settings.py 用自己的中间件替换默认中间件

DOWNLOADER_MIDDLEWARES = {'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware': None,'myscrapy.middlewares.UserAgentMiddleware': 500
}

输出如下：

request headers:
{b'Accept': [b'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'], b'Accept-Language': [b'en'], b'User-Agent': [b'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.93 Safari/537.36'], b'Accept-Encoding': [b'gzip,deflate']
}

关于scrapy请求头设置，可以参考我之前的文章：
https://blog.csdn.net/mouday/article/details/80776030

cookies

上面的信息中少了个response.cookies，如果添加上回报错：

AttributeError: 'TextResponse' object has no attribute 'cookies'

说明响应是不带cookies参数的

通过 http://httpbin.org/cookies 测试cookies

# -*- coding: utf-8 -*-from scrapy import Spider, Request
import loggingclass MySpider(Spider):name = 'my_spider'allowed_domains = ['httpbin.org']start_urls = ['http://httpbin.org/cookies']def start_requests(self):for url in self.start_urls:yield Request(url, cookies={"username": "pengshiyu"})def parse(self, response):logging.debug("*" * 40)logging.debug("response text: %s" % response.text)logging.debug("request headers: %s" % response.request.headers)logging.debug("request cookies: %s" % response.request.cookies)if __name__ == '__main__':from scrapy import cmdlinecmdline.execute("scrapy crawl my_spider".split())

返回值如下：

response text:
{"cookies":{"username":"pengshiyu"}
}request headers:
{b'Accept': [b'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'], b'Accept-Language': [b'en'], b'User-Agent': [b'Scrapy/1.5.1 (+https://scrapy.org)'], b'Accept-Encoding': [b'gzip,deflate'], b'Cookie': [b'username=pengshiyu']
}request cookies:
{'username': 'pengshiyu'
}

服务器端已经接收到我的cookie值了，不过request的headers也包含了相同的cookie，保存到了键为Cookie下面

其实并没有什么cookie，浏览器请求的·cookies·被包装到了·headers·中发送给服务器端
既然这样，在headers中包含Cookie试试

 def start_requests(self):for url in self.start_urls:yield Request(url, headers={"Cookie": {"username": "pengshiyu"}})

返回结果

response text:
{"cookies":{}
}request headers:
{b'Accept': [b'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'], b'Accept-Language': [b'en'], b'User-Agent': [b'Scrapy/1.5.1 (+https://scrapy.org)'], b'Accept-Encoding': [b'gzip,deflate']
}request cookies:
{}

cookies 是空的，设置失败

我们找到 default_settings 中的cookie中间件

'scrapy.downloadermiddlewares.cookies.CookiesMiddleware': 700


class CookiesMiddleware(object):"""This middleware enables working with sites that need cookies"""def __init__(self, debug=False):self.jars = defaultdict(CookieJar)self.debug = debug@classmethoddef from_crawler(cls, crawler):if not crawler.settings.getbool('COOKIES_ENABLED'):raise NotConfiguredreturn cls(crawler.settings.getbool('COOKIES_DEBUG'))def process_request(self, request, spider):if request.meta.get('dont_merge_cookies', False):returncookiejarkey = request.meta.get("cookiejar")jar = self.jars[cookiejarkey]cookies = self._get_request_cookies(jar, request)for cookie in cookies:jar.set_cookie_if_ok(cookie, request)# set Cookie headerrequest.headers.pop('Cookie', None)jar.add_cookie_header(request)self._debug_cookie(request, spider)def process_response(self, request, response, spider):if request.meta.get('dont_merge_cookies', False):return response# extract cookies from Set-Cookie and drop invalid/expired cookiescookiejarkey = request.meta.get("cookiejar")jar = self.jars[cookiejarkey]jar.extract_cookies(response, request)self._debug_set_cookie(response, spider)return responsedef _debug_cookie(self, request, spider):if self.debug:cl = [to_native_str(c, errors='replace')for c in request.headers.getlist('Cookie')]if cl:cookies = "\n".join("Cookie: {}\n".format(c) for c in cl)msg = "Sending cookies to: {}\n{}".format(request, cookies)logger.debug(msg, extra={'spider': spider})def _debug_set_cookie(self, response, spider):if self.debug:cl = [to_native_str(c, errors='replace')for c in response.headers.getlist('Set-Cookie')]if cl:cookies = "\n".join("Set-Cookie: {}\n".format(c) for c in cl)msg = "Received cookies from: {}\n{}".format(response, cookies)logger.debug(msg, extra={'spider': spider})def _format_cookie(self, cookie):# build cookie stringcookie_str = '%s=%s' % (cookie['name'], cookie['value'])if cookie.get('path', None):cookie_str += '; Path=%s' % cookie['path']if cookie.get('domain', None):cookie_str += '; Domain=%s' % cookie['domain']return cookie_strdef _get_request_cookies(self, jar, request):if isinstance(request.cookies, dict):cookie_list = [{'name': k, 'value': v} for k, v in \six.iteritems(request.cookies)]else:cookie_list = request.cookiescookies = [self._format_cookie(x) for x in cookie_list]headers = {'Set-Cookie': cookies}response = Response(request.url, headers=headers)return jar.make_cookies(response, request)

观察源码，发现以下几个方法

# process_request
jar.add_cookie_header(request)   # 添加cookie到headers# process_response
jar.extract_cookies(response, request)  # 提取出cookie# _debug_cookie
request.headers.getlist('Cookie')  # 从headers获取cookie# _debug_set_cookie
response.headers.getlist('Set-Cookie')  # 从headers获取Set-Cookie

几个参数：

# settings
COOKIES_ENABLED
COOKIES_DEBUG# meta
dont_merge_cookies
cookiejar# headers
Cookie
Set-Cookie

使用最开始cookie部分的代码，为了看的清晰，我删除了headers中其他参数，下面逐个做测试

1、COOKIES_ENABLED

COOKIES_ENABLED = True (默认)

response text:
{"cookies":{"username":"pengshiyu"}
}request headers:
{b'Cookie': [b'username=pengshiyu']
}request cookies:
{'username': 'pengshiyu'
}

一切ok
COOKIES_ENABLED = False

response text:
{"cookies":{}
}request headers:
{}request cookies:
{'username': 'pengshiyu'
}

虽然request的cookies有内容，不过headers没有加进去，所以服务器端没有获取到cookie

注意：查看请求的真正cookie，应该在request的header中查看

2、COOKIES_DEBUG
COOKIES_DEBUG = False (默认)

DEBUG: Crawled (200) <GET http://httpbin.org/cookies> (referer: None)

COOKIES_DEBUG = True
多输出了下面一句，可以看到我设置的cookie

[scrapy.downloadermiddlewares.cookies] DEBUG: Sending cookies to: <GET http://httpbin.org/cookies>
Cookie: username=pengshiyu

当然，debug模式下服务器肯定能正常接收我的cookie

3、dont_merge_cookies
设置meta={"dont_merge_cookies": True} 默认为 False

response text:
{"cookies":{}
}request headers:
{}request cookies:
{'username': 'pengshiyu'
}

服务器并没有接收到我的cookie

4、cookiejar
直接通过response.request.meta.get("cookiejar")获取


response text:
{"cookies":{"username":"pengshiyu"}}request headers:
{b'Cookie': [b'username=pengshiyu']}request cookies:
{'username': 'pengshiyu'}request cookiejar:
None

啥也没有

5、Cookie
直接获取：response.request.headers.get("Cookie"))

headers Cookie:
b'username=pengshiyu'

看来这里已经被处理成字节串了

修改Request请求参数
cookies={"username": "pengshiyu", "password": "123456"}

# response.request.headers.get("Cookie"))
headers Cookie:
b'username=pengshiyu; password=123456'# request.headers.getlist('Cookie')
headers Cookies:
[b'username=pengshiyu; password=123456']

很明显，两个获取方式，一个获取的是字符串，一个获取的是列表

6、Set-Cookie

同样，我通过以下

response.headers.get("Set-Cookie")
response.headers.getlist("Set-Cookie")

还是啥都没有

headers Set-Cookie: None
headers Set-Cookies: []

不过，到目前为止，cookie设置的大概流程应该如下：

request cookies: {'username': 'pengshiyu', 'password': '123456'}
request cookiejar: None
request Cookie: b'username=pengshiyu; password=123456'
response text: {"cookies":{"password":"123456","username":"pengshiyu"}}
response Set-Cookie: None
response Set-Cookies: []

7、接收服务器传递过来的cookie

将请求链接改为：’http://httpbin.org/cookies/set/key/value’
开启 COOKIES_DEBUG
在debug中看到如下变化

Sending cookies to: <GET http://httpbin.org/cookies/set/key/value>
Cookie: username=pengshiyu; password=123456Received cookies from: <302 http://httpbin.org/cookies/set/key/value>
Set-Cookie: key=value; Path=/Redirecting (302) to <GET http://httpbin.org/cookies> from <GET http://httpbin.org/cookies/set/key/value>Sending cookies to: <GET http://httpbin.org/cookies>
Cookie: key=value; username=pengshiyu; password=123456

日志看出他进行了两次请求，看到中间的cookie变化：

发送 -> 接收 -> 发送

第二次发送的cookie包含了第一次请求时服务器端传递过来的cookie，说明scrapy对服务器端和客户端的cookie进行了管理

最后的cookie输出

request cookies: {'username': 'pengshiyu', 'password': '123456'}
request cookiejar: None
request Cookie: b'key=value; username=pengshiyu; password=123456'
response text: {"cookies":{"key":"value","password":"123456","username":"pengshiyu"}}
response Set-Cookie: None

request的cookies并没有变化，而request.headers.get(“Cookie”)已经发生了变化

8、接收服务器传递过来的同key键cookie
将请求链接换为：httpbin.org/cookies/set/username/pengpeng

Sending cookies to: <GET http://httpbin.org/cookies/set/username/pengpeng>
Cookie: username=pengshiyuReceived cookies from: <302 http://httpbin.org/cookies/set/username/pengpeng>
Set-Cookie: username=pengpeng; Path=/Redirecting (302) to <GET http://httpbin.org/cookies> from <GET http://httpbin.org/cookies/set/username/pengpeng>Sending cookies to: <GET http://httpbin.org/cookies>
Cookie: username=pengshiyu

发现虽然收到了username=pengpeng但是，第二次发请求的时候，又发送了原来的的cookieusername=pengshiyu

这说明客户端设置的cookie优先级高于服务器端传递过来的cookie

9、取消使用中间件CookiesMiddleware

DOWNLOADER_MIDDLEWARES = {'scrapy.downloadermiddlewares.cookies.CookiesMiddleware': None
}

请求链接：http://httpbin.org/cookies

request cookies: {'username': 'pengshiyu'}
request cookiejar: None
request Cookie: None
response text: {"cookies":{}}
response Set-Cookie: None
response Set-Cookies: []

这个效果类似COOKIES_ENABLED = False

10、自定义cookie池

class RandomCookiesMiddleware(object):def process_request(self, request, spider):cookies = []cookie = random.choice(cookies)request.cookies = cookie

同样需要设置

DOWNLOADER_MIDDLEWARES = {'myscrapy.middlewares.RandomCookiesMiddleware': 600
}

注意到scrapy的中间件CookiesMiddleware值是700,为了cookie设置生效，需要在这个中间件启用之前就设置好自定义的cookie，优先级按照从小到大的顺序执行，所以我们自己自定义的cookie中间件需要小于 < 700

'scrapy.downloadermiddlewares.cookies.CookiesMiddleware': 700,

总结

参数	设置	获取	说明
meta	Request(url, meta={“uid”: “100”}) request.meta[“uid”] = “100”	response.request.meta.get(“uid”) response.meta.get(“uid”)	携带request参数给response,或设置代理
headers	Request(url, headers={“User-Agent”: “chrome”}) request.headers[“User-Agent”]=”chrome” USER_AGENT=”chrome”	response.request.headers.get(“User-Agent”)	设置客户端请求头参数
cookies	Request(url, cookies={“username”: “pengshiyu”} ) request.cookies = {“username”: “pengshiyu”}	response.request.cookies response.request.headers.get(“Cookie”) response.headers.get(‘Set-Cookie’)	客户端请求头中的Cookie参数，管理客户端与服务器端之间的会话识别

常用的中间件如下

import random
from fake_useragent import UserAgentclass RandomUserAgentMiddleware(object):def process_request(self, request, spider):ua = UserAgent()user_agent = ua.chromerequest.headers.setdefault(b'User-Agent', user_agent)class RandomProxyMiddleware(object):def process_request(self, request, spider):proxies = []proxy = random.choice(proxies)request.meta["proxy"] = proxyclass RandomCookiesMiddleware(object):def process_request(self, request, spider):cookies = []cookie = random.choice(cookies)request.cookies = cookie

当然，cookies 和 proxies 需要结合自己的情况补全

Python爬虫：scrapy框架请求参数meta、headers、cookies一探究竟相关推荐

python爬虫--Scrapy框架--Scrapy+selenium实现动态爬取
python爬虫–Scrapy框架–Scrapy+selenium实现动态爬取前言本文基于数据分析竞赛爬虫阶段,对使用scrapy + selenium进行政策文本爬虫进行记录.用于个人爬虫学习记 ...
Python爬虫—Scrapy框架—Win10下载安装
Python爬虫-Scrapy框架-Win10下载安装 1. 下载wheel 2.下载twisted 3. 下载pywin32 4. 下载安装Scrapy 5. 创建一个scrapy项目 6. fir ...
Python爬虫 scrapy框架爬取某招聘网存入mongodb解析
这篇文章主要介绍了Python爬虫 scrapy框架爬取某招聘网存入mongodb解析,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下创建项目 sc ...
Python爬虫-Scrapy框架（四）- 内置爬虫文件 - 4.2 初探Crawl Spider
Python爬虫-Scrapy框架(四)- 内置爬虫文件 - 4.2 初探Crawl Spider 写在前面初探Crawl Spider 创建Crawl Spider项目对比Basic与Crawl ...
Python爬虫——Scrapy框架（附有实战）
大家好!我是霖hero 有一天,我在逛街,突然被一声靓仔打断了我的脚步,回头一看,原来是水果摊阿姨叫我买水果,说我那么靓仔,便宜一点买给我,自恋的我无法拒绝阿姨的一声声靓仔,于是买了很多水果回家,家人 ...
Python爬虫scrapy框架的源代码分析
scrapy框架流程图推荐三个网址:官方1.5版本:https://doc.scrapy.org/en/latest/topics/architecture.html点击打开链接官方0.24版本( ...
python爬虫scrapy框架教程_Python爬虫教程-30-Scrapy 爬虫框架介绍
从本篇开始学习 Scrapy 爬虫框架 Python爬虫教程-30-Scrapy 爬虫框架介绍框架:框架就是对于相同的相似的部分,代码做到不出错,而我们就可以将注意力放到我们自己的部分了常见爬虫框 ...
Python爬虫——Scrapy框架
Scrapy是用python实现的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.使用Twisted高效异步网络框架来处理网络通信. Scrapy架构: ScrapyEngine:引擎.负责控制 ...
Python爬虫——scrapy框架介绍
一.什么是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,非常出名,非常强悍.所谓的框架就是一个已经被集成了各种功能(高性能异步下载,队列,分布式,解析,持久化等) ...

Python爬虫：scrapy框架请求参数meta、headers、cookies一探究竟

原生参数

meta

headers

cookies

总结

Python爬虫：scrapy框架请求参数meta、headers、cookies一探究竟相关推荐

最新文章

热门文章