Scrapy模拟登陆

Posted 2021-09-13 ZSYL

Scrapy模拟登陆

• 1. 回顾之前的模拟登陆的方法
• • 1.1 requests模块是如何实现模拟登陆的？
  • 1.2 selenium是如何模拟登陆的？
  • 1.3 scrapy的模拟登陆
• 2. scrapy携带cookies直接获取需要登陆后的页面
• • 2.1 实现：重构scrapy的starte_rquests方法
  • 2.2 携带cookies登陆github
• 3. scrapy.Request发送post请求
• • 3.1 发送post请求
  • • 3.1.1 思路分析
    • 3.1.2 代码实现如下
• 4. 完整代码
• 5. 小结

学习目标：

1. 应用 请求对象cookies参数的使用
2. 了解 start_requests函数的作用
3. 应用 构造并发送post请求

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1. 回顾之前的模拟登陆的方法

1.1 requests模块是如何实现模拟登陆的？

1. 直接携带cookies请求页面
2. 找url地址，发送post请求存储cookie

1.2 selenium是如何模拟登陆的？

1. 找到对应的input标签，输入文本点击登陆

1.3 scrapy的模拟登陆

1. 直接携带cookies
2. 找url地址，发送post请求存储cookie

2. scrapy携带cookies直接获取需要登陆后的页面

应用场景

1. cookie过期时间很长，常见于一些不规范的网站
2. 能在cookie过期之前把所有的数据拿到
3. 配合其他程序使用，比如其使用selenium把登陆之后的cookie获取到保存到本地，scrapy发送请求之前先读取本地cookie

2.1 实现：重构scrapy的starte_rquests方法

scrapy中start_url是通过start_requests来进行处理的，其实现代码如下

# 这是源代码
def start_requests(self):
    cls = self.__class__
    if method_is_overridden(cls, Spider, 'make_requests_from_url'):
        warnings.warn(
            "Spider.make_requests_from_url method is deprecated; it "
            "won't be called in future Scrapy releases. Please "
            "override Spider.start_requests method instead (see %s.%s)." % (
                cls.__module__, cls.__name__
            ),
        )
        for url in self.start_urls:
            yield self.make_requests_from_url(url)
    else:
        for url in self.start_urls:
            yield Request(url, dont_filter=True)

所以对应的，如果start_url地址中的url是需要登录后才能访问的url地址，则需要重写start_request方法并在其中手动添加上cookie

2.2 携带cookies登陆github

测试账号 noobpythoner zhoudawei123

import scrapy
import re

class Login1Spider(scrapy.Spider):
    name = 'login1'
    allowed_domains = ['github.com']
    start_urls = ['https://github.com/NoobPythoner'] # 这是一个需要登陆以后才能访问的页面

    def start_requests(self): # 重构start_requests方法
        # 这个cookies_str是抓包获取的
        cookies_str = '...' # 抓包获取
        # 将cookies_str转换为cookies_dict
        cookies_dict = {i.split('=')[0]:i.split('=')[1] for i in cookies_str.split('; ')}
        yield scrapy.Request(
            self.start_urls[0],
            callback=self.parse,
            cookies=cookies_dict
        )

    def parse(self, response): # 通过正则表达式匹配用户名来验证是否登陆成功
        # 正则匹配的是github的用户名
        result_list = re.findall(r'noobpythoner|NoobPythoner', response.body.decode()) 
        print(result_list)
        pass

注意：

1. scrapy中cookie不能够放在headers中，在构造请求的时候有专门的cookies参数，能够接受字典形式的coookie
2. 在setting中设置ROBOTS协议、USER_AGENT

3. scrapy.Request发送post请求

我们知道可以通过scrapy.Request()指定method、body参数来发送post请求；但是通常使用scrapy.FormRequest()来发送post请求

3.1 发送post请求

注意：scrapy.FormRequest()能够发送表单和ajax请求，参考阅读 https://www.jb51.net/article/146769.htm

3.1.1 思路分析

1. 找到post的url地址：点击登录按钮进行抓包，然后定位url地址为https://github.com/session

2. 找到请求体的规律：分析post请求的请求体，其中包含的参数均在前一次的响应中

3. 是否登录成功：通过请求个人主页，观察是否包含用户名

3.1.2 代码实现如下

import scrapy
import re

class Login2Spider(scrapy.Spider):
   name = 'login2'
   allowed_domains = ['github.com']
   start_urls = ['https://github.com/login']

   def parse(self, response):
       authenticity_token = response.xpath("//input[@name='authenticity_token']/@value").extract_first()
       utf8 = response.xpath("//input[@name='utf8']/@value").extract_first()
       commit = response.xpath("//input[@name='commit']/@value").extract_first()
        
        #构造POST请求，传递给引擎
       yield scrapy.FormRequest(
           "https://github.com/session",
           formdata={
               "authenticity_token":authenticity_token,
               "utf8":utf8,
               "commit":commit,
               "login":"noobpythoner",
               "password":"***"
           },
           callback=self.parse_login
       )

   def parse_login(self,response):
       ret = re.findall(r"noobpythoner|NoobPythoner",response.text)
       print(ret)

小技巧

在settings.py中通过设置COOKIES_DEBUG=TRUE 能够在终端看到cookie的传递传递过程

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4. 完整代码

携带cookie：

import scrapy
'''
cookie: _octo=GH1.1.578198759.1625640541; _device_id=73970f074a72a725ce83e5614a029e94; user_session=Vi81uuZiPlIf3qArUwSsgacHOhALXHsz0qyT0hmZ_vsM2Yc2; __Host-user_session_same_site=Vi81uuZiPlIf3qArUwSsgacHOhALXHsz0qyT0hmZ_vsM2Yc2; logged_in=yes; dotcom_user=ZS22YL; has_recent_activity=1; color_mode=%7B%22color_mode%22%3A%22light%22%2C%22light_theme%22%3A%7B%22name%22%3A%22light%22%2C%22color_mode%22%3A%22light%22%7D%2C%22dark_theme%22%3A%7B%22name%22%3A%22dark%22%2C%22color_mode%22%3A%22dark%22%7D%7D; tz=Asia%2FShanghai; _gh_sess=XlUioEY6UokxY%2B9s70Nux38MEhGjD0ToEd6DNogQFPeLQVQ3swInqD4p07cF2xTGT7HXEMB4F%2FIct0fpz2vrRBve4OE83Oaa1Hrxg817QdvarqZS15oTIqmAl%2BVfkRHp9%2Fv2zaWq%2Fe4vE1XyryEavzvBeNOqagA4PZGVUzFjT632R7Spcs0J5lhRXbW4Hspw--lO5I7cZqd%2Bxyv13Q--qk7MIsiu0UOti98YInJ%2BvA%3D%3D
'''

class Git1Spider(scrapy.Spider):
    name = 'git1'
    allowed_domains = ['github.com']
    start_urls = ['https://github.com/username']

    def start_requests(self):
        url = self.start_urls[0]

        temp = '_octo=GH1.1.578198759.1625640541; _device_id=73970f074a72a725ce83e5614a029e94; user_session=Vi81uuZiPlIf3qArUwSsgacHOhALXHsz0qyT0hmZ_vsM2Yc2; __Host-user_session_same_site=Vi81uuZiPlIf3qArUwSsgacHOhALXHsz0qyT0hmZ_vsM2Yc2; logged_in=yes; dotcom_user=ZS22YL; has_recent_activity=1; color_mode=%7B%22color_mode%22%3A%22light%22%2C%22light_theme%22%3A%7B%22name%22%3A%22light%22%2C%22color_mode%22%3A%22light%22%7D%2C%22dark_theme%22%3A%7B%22name%22%3A%22dark%22%2C%22color_mode%22%3A%22dark%22%7D%7D; tz=Asia%2FShanghai; _gh_sess=XlUioEY6UokxY%2B9s70Nux38MEhGjD0ToEd6DNogQFPeLQVQ3swInqD4p07cF2xTGT7HXEMB4F%2FIct0fpz2vrRBve4OE83Oaa1Hrxg817QdvarqZS15oTIqmAl%2BVfkRHp9%2Fv2zaWq%2Fe4vE1XyryEavzvBeNOqagA4PZGVUzFjT632R7Spcs0J5lhRXbW4Hspw--lO5I7cZqd%2Bxyv13Q--qk7MIsiu0UOti98YInJ%2BvA%3D%3D'
		# 字典推导式生成cookie
        cookies = {data.split('=')[0]: data.split('=')[-1] for data in temp.split('; ')}
		# 发送给引擎，新的请求
        yield scrapy.Request(
            url=url,
            callback=self.parse,
            cookies=cookies
        )
        
	# 解析响应，查看是够成功登录（名字后面之后有.github）
    def parse(self, response):
        print(response.xpath('/html/head/title/text()').extract_first())

模拟登录

import scrapy


class Git2Spider(scrapy.Spider):
    name = 'git2'
    allowed_domains = ['github.com']
    start_urls = ['http://github.com/login']

    def parse(self, response):
        # 从登录页面响应中解析出post数据
        token = response.xpath('//input[@name="authenticity_token"]/@value').extract_first()

        post_data = {
                'commit': 'Sign in',
                'authenticity_token': token,
                'login': 'username',
                'password': 'password',
                'webauthn-support': 'supported',
                'webauthn-iuvpaa-support': 'unsupported',
                'return_to': 'https://github.com/login',
                'timestamp': '1629970060446',
                'timestamp_secret': 'e472904d9d6e3c5512dd549e9a4b03d4d869090b895fa8f1ddfd8dde8d72c5f6'
        }
        print(post_data)
        # 针对登录url发送post请求
        yield scrapy.FormRequest(
            url='http://github.com/session',
            callback=self.after_login,
            formdata=post_data
        )

    def after_login(self, response):
        yield scrapy.Request('https://github.com/username', callback=self.check_login)

    def check_login(self, response):
        print(response.xpath('/html/head/title/text()').extract_first())

5. 小结

1. start_urls中的url地址是交给start_request处理的，如有必要，可以重写start_request函数
2. 直接携带cookie登陆：cookie只能传递给cookies参数接收
3. scrapy.Request()发送post请求

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