python伪造请求头x-forwarded-for的作用_Pyspider中给爬虫伪造随机请求头的实例
Pyspider 中采用了 tornado 庫來做 http 請求，在請求過程中可以添加各種參數，例如請求鏈接超時時間，請求傳輸數據超時時間，請求頭等等，但是根據pyspider的原始框架，給爬蟲添加參數只能通過 crawl_config這個Python字典來完成(如下所示)，框架代碼將這個字典中的參數轉換成 task 數據，進行http請求。這個參數的缺點是不方便給每一次請求做隨機請求頭。
crawl_config = {
"user_agent": "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36",
"timeout": 120,
"connect_timeout": 60,
"retries": 5,
"fetch_type": 'js',
"auto_recrawl": True,
}
這里寫出給爬蟲添加隨機請求頭的方法：
1、編寫腳本，將腳本放置在 pyspider 的 libs 文件夾下，命名為 header_switch.py
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Created on 2017-10-18 11:52:26
import random
import time
class HeadersSelector(object):
"""
Header 中缺少幾個字段 Host 和 Cookie
"""
headers_1 = {
"Proxy-Connection": "keep-alive",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"User-Agent": "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36",
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"DNT": "1",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.6,en;q=0.4",
"Referer": "https://www.baidu.com/s?wd=%BC%96%E7%A0%81&rsv_spt=1&rsv_iqid=0x9fcbc99a0000b5d7&issp=1&f=8&rsv_bp=1&rsv_idx=2&ie=utf-8&rqlang=cn&tn=baiduhome_pg&rsv_enter=0&oq=If-None-Match&inputT=7282&rsv_t",
"Accept-Charset": "gb2312,gbk;q=0.7,utf-8;q=0.7,*;q=0.7",
} # 網上找的瀏覽器
headers_2 = {
"Proxy-Connection": "keep-alive",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"User-Agent": "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.221 Safari/537.36 SE 2.X MetaSr 1.0",
"Accept": "image/gif,image/x-xbitmap,image/jpeg,application/x-shockwave-flash,application/vnd.ms-excel,application/vnd.ms-powerpoint,application/msword,*/*",
"DNT": "1",
"Referer": "https://www.baidu.com/link?url=c-FMHf06-ZPhoRM4tWduhraKXhnSm_RzjXZ-ZTFnPAvZN",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.6,en;q=0.4",
} # window 7 系統瀏覽器
headers_3 = {
"Proxy-Connection": "keep-alive",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0",
"Accept": "image/x-xbitmap,image/jpeg,application/x-shockwave-flash,application/vnd.ms-excel,application/vnd.ms-powerpoint,application/msword,*/*",
"DNT": "1",
"Referer": "https://www.baidu.com/s?wd=http%B4%20Pragma&rsf=1&rsp=4&f=1&oq=Pragma&tn=baiduhome_pg&ie=utf-8&usm=3&rsv_idx=2&rsv_pq=e9bd5e5000010",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.7,en;q=0.6",
} # Linux 系統 firefox 瀏覽器
headers_4 = {
"Proxy-Connection": "keep-alive",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:55.0) Gecko/20100101 Firefox/55.0",
"Accept": "*/*",
"DNT": "1",
"Referer": "https://www.baidu.com/link?url=c-FMHf06-ZPhoRM4tWduhraKXhnSm_RzjXZ-ZTFnP",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.9,en-US;q=0.7,en;q=0.6",
} # Win10 系統 firefox 瀏覽器
headers_5 = {
"Connection": "keep-alive",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64;) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36 Edge/15.15063",
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Referer": "https://www.baidu.com/link?url=c-FMHf06-ZPhoRM4tWduhraKXhnSm_RzjXZ-",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.9,en-US;q=0.7,en;q=0.6",
"Accept-Charset": "gb2312,gbk;q=0.7,utf-8;q=0.7,*;q=0.7",
} # Win10 系統 Chrome 瀏覽器
headers_6 = {
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Encoding": "gzip, deflate, sdch",
"Accept-Language": "zh-CN,zh;q=0.8",
"Pragma": "no-cache",
"Cache-Control": "no-cache",
"Connection": "keep-alive",
"DNT": "1",
"Referer": "https://www.baidu.com/s?wd=If-None-Match&rsv_spt=1&rsv_iqid=0x9fcbc99a0000b5d7&issp=1&f=8&rsv_bp=1&rsv_idx=2&ie=utf-8&rq",
"Accept-Charset": "gb2312,gbk;q=0.7,utf-8;q=0.7,*;q=0.7",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.221 Safari/537.36 SE 2.X MetaSr 1.0",
} # win10 系統瀏覽器
def __init__(self):
pass
def select_header(self):
n = random.randint(1, 6)
switch={
1: self.headers_1
2: self.headers_2
3: self.headers_3
4: self.headers_4
5: self.headers_5
6: self.headers_6
}
headers = switch[n]
return headers
其中，我只寫了6個請求頭，如果爬蟲的量非常大，完全可以寫更多的請求頭，甚至上百個，然后將 random的隨機范圍擴大，進行選擇。
2、在pyspider 腳本中編寫如下代碼：
#!/usr/bin/env python
# -*- encoding: utf-8 -*-
# Created on 2017-08-18 11:52:26
from pyspider.libs.base_handler import *
from pyspider.addings.headers_switch import HeadersSelector
import sys
defaultencoding = 'utf-8'
if sys.getdefaultencoding() != defaultencoding:
reload(sys)
sys.setdefaultencoding(defaultencoding)
class Handler(BaseHandler):
crawl_config = {
"user_agent": "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36",
"timeout": 120,
"connect_timeout": 60,
"retries": 5,
"fetch_type": 'js',
"auto_recrawl": True,
}
@every(minutes=24 * 60)
def on_start(self):
header_slt = HeadersSelector()
header = header_slt.select_header() # 獲取一個新的 header
# header["X-Requested-With"] = "XMLHttpRequest"
orig_href = 'http://sww.bjxch.gov.cn/gggs.html'
self.crawl(orig_href,
callback=self.index_page,
headers=header) # 請求頭必須寫在 crawl 里，cookies 從 response.cookies 中找
@config(age=24 * 60 * 60)
def index_page(self, response):
header_slt = HeadersSelector()
header = header_slt.select_header() # 獲取一個新的 header
# header["X-Requested-With"] = "XMLHttpRequest"
if response.cookies:
header["Cookies"] = response.cookies
其中最重要的就是在每個回調函數 on_start，index_page 等等 當中，每次調用時，都會實例化一個 header 選擇器，給每一次請求添加不一樣的 header。要注意添加的如下代碼：
header_slt = HeadersSelector()
header = header_slt.select_header() # 獲取一個新的 header
# header["X-Requested-With"] = "XMLHttpRequest"
header["Host"] = "www.baidu.com"
if response.cookies:
header["Cookies"] = response.cookies
當使用 XHR 發送 AJAX 請求時會帶上 Header，常被用來判斷是不是 Ajax 請求， headers 要添加 {‘X-Requested-With': ‘XMLHttpRequest'} 才能抓取到內容。
確定了 url 也就確定了請求頭中的 Host，需要按需添加，urlparse包里給出了根據 url解析出 host的方法函數，直接調用netloc即可。
如果響應中有 cookie，就需要將 cookie 添加到請求頭中。
如果還有別的偽裝需求，自行添加。
如此即可實現隨機請求頭，完。
以上這篇Pyspider中給爬蟲偽造隨機請求頭的實例就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持我們。
本文標題: Pyspider中給爬蟲偽造隨機請求頭的實例
本文地址: http://www.cppcns.com/jiaoben/python/227296.html
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