一、定義實現隨機User-Agent的下載中間件

1.在middlewares.py中完善代碼

 1 import random
 2 from Tencent.settings import USER_AGENTS_LIST # 註意導入路徑,請忽視pycharm的錯誤提示
 3 
 4 class UserAgentMiddleware(object):
 5     def process_request(self, request, spider):
 6         user_agent = random.choice(USER_AGENTS_LIST)
 7
 
         request.headers[‘User-Agent‘] = user_agent
 8         # 不寫return
 9 
10 class CheckUA:
11     def process_response(self,request,response,spider):
12         print(request.headers[‘User-Agent‘])
13         return response # 不能少！

2.在settings中設置開啟自定義的下載中間件，設置方法同管道

1 DOWNLOADER_MIDDLEWARES = {
 
2    ‘Tencent.middlewares.UserAgentMiddleware‘: 543, # 543是權重值
3    ‘Tencent.middlewares.CheckUA‘: 600, # 先執行543權重的中間件，再執行600的中間件
4 }

3.在settings中添加UA的列表

1 USER_AGENTS_LIST = [
2     "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)
 
",
3     "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
4     "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
5     "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
6     "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5"
7 ]

二、代理ip的使用

1.在middlewares.py中完善代碼

 1 class RandomProxy(object):
 2 
 3     def process_request(self, request, spider):
 4 
 5         proxy = random.choice(PROXY_LIST)
 6         print(proxy)
 7 
 8         if ‘user_passwd‘ in proxy:
 9             # 對賬號密碼進行編碼，基礎認證,python3中需要是bytes類型的數據才能編碼
10             b64_up = base64.b64encode(proxy[‘user_passwd‘].encode())
11 
12             # 進行代理認證
13             request.headers[‘Proxy-Authorization‘] = ‘Basic ‘ + b64_up.decode()
14 
15             # 設置代理
16             request.meta[‘proxy‘] = proxy[‘ip_port‘]
17         else:
18             #設置代理
19             request.meta[‘proxy‘] = proxy[‘ip_port‘]

2.檢測代理ip是否可用

在使用了代理ip的情況下可以在下載中間件的process_response()方法中處理代理ip的使用情況，如果該代理ip不能使用可以替換其他代理ip

1 class ProxyMiddleware(object):
2     ......
3     def process_response(self, request, response, spider):
4         if response.status != ‘200‘:
5             request.dont_filter = True # 重新發送的請求對象能夠再次進入隊列
6             return requst

3.在settings中添加代理ip的列表

1 PROXY_LIST = [
2     {"ip_port": "139.199.121.163:16818", "user_passwd": "user:password"},#收費代理
3     # {"ip_port": "114.234.81.72:9000"} # 免費代理
4 ]

三. 在中間件中使用selenium

以github登陸為例

1. 完成爬蟲代碼

 1 import scrapy
 2 
 3 class Login4Spider(scrapy.Spider):
 4     name = ‘login4‘
 5     allowed_domains = [‘github.com‘]
 6     start_urls = [‘https://github.com/returnes‘] # 直接對驗證的url發送請求
 7 
 8     def parse(self, response):
 9         with open(‘check.html‘, ‘w‘) as f:
10             f.write(response.body.decode())

2.在middlewares.py中使用selenium

 1 import time
 2 from selenium import webdriver
 3 
 4 
 5 def getCookies():
 6     # 使用selenium模擬登陸，獲取並返回cookie
 7     username = input(‘輸入github賬號:‘)
 8     password = input(‘輸入github密碼:‘)
 9     options = webdriver.ChromeOptions()
10     options.add_argument(‘--headless‘)
11     options.add_argument(‘--disable-gpu‘)
12     driver = webdriver.Chrome(‘/home/worker/Desktop/driver/chromedriver‘,
13                               chrome_options=options)
14     driver.get(‘https://github.com/login‘)
15     time.sleep(1)
16     driver.find_element_by_xpath(‘//*[@id="login_field"]‘).send_keys(username)
17     time.sleep(1)
18     driver.find_element_by_xpath(‘//*[@id="password"]‘).send_keys(password)
19     time.sleep(1)
20     driver.find_element_by_xpath(‘//*[@id="login"]/form/div[3]/input[3]‘).click()
21     time.sleep(2)
22     cookies_dict = {cookie[‘name‘]: cookie[‘value‘] for cookie in driver.get_cookies()}
23     driver.quit()
24     return cookies_dict
25 
26 class LoginDownloaderMiddleware(object):
27 
28     def process_request(self, request, spider):
29         cookies_dict = getCookies()
30         print(cookies_dict)
31         request.cookies = cookies_dict # 對請求對象的cookies屬性進行替換

Scrapy中間件user-agent和ip代理使用