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Pyspider中给爬虫伪造随机请求头的实例

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[开发(python) 所属分类 开发(python) | 发布者 店小二03 | 时间 | 作者 红领巾 ] 0人收藏点击收藏

Pyspider 中采用了 tornado 库来做 http 请求,在请求过程中可以添加各种参数,例如请求链接超时时间,请求传输数据超时时间,请求头等等,但是根据pyspider的原始框架,给爬虫添加参数只能通过 crawl_config这个python字典来完成(如下所示),框架代码将这个字典中的参数转换成 task 数据,进行http请求。这个参数的缺点是不方便给每一次请求做随机请求头。

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,
}

这里写出给爬虫添加随机请求头的方法:

1、编写脚本,将脚本放置在 pyspider 的 libs 文件夹下,命名为 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 中缺少几个字段 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",
} # 网上找的浏览器
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 系统浏览器
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 系统 firefox 浏览器
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 系统 firefox 浏览器
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 系统 Chrome 浏览器
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 系统浏览器
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,我只写了6个请求头,如果爬虫的量非常大,完全可以写更多的请求头,甚至上百个,然后将 random的随机范围扩大,进行选择。

2、在pyspider 脚本中编写如下代码:

#!/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() # 获取一个新的 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) # 请求头必须写在 crawl 里,cookies 从 response.cookies 中找
@config(age=24 * 60 * 60)
def index_page(self, response):
header_slt = HeadersSelector()
header = header_slt.select_header() # 获取一个新的 header
# header["X-Requested-With"] = "XMLHttpRequest"
if response.cookies:
header["Cookies"] = response.cookies

其中最重要的就是在每个回调函数 on_start,index_page 等等 当中,每次调用时,都会实例化一个 header 选择器,给每一次请求添加不一样的 header。要注意添加的如下代码:

header_slt = HeadersSelector()
header = header_slt.select_header() # 获取一个新的 header
# header["X-Requested-With"] = "XMLHttpRequest"
header["Host"] = "www.baidu.com"
if response.cookies:
header["Cookies"] = response.cookies

当使用 XHR 发送 AJAX 请求时会带上 Header,常被用来判断是不是 Ajax 请求, headers 要添加 {‘X-Requested-With': ‘XMLHttpRequest'} 才能抓取到内容。

确定了 url 也就确定了请求头中的 Host,需要按需添加,urlparse包里给出了根据 url解析出 host的方法函数,直接调用netloc即可。

如果响应中有 cookie,就需要将 cookie 添加到请求头中。

如果还有别的伪装需求,自行添加。

如此即可实现随机请求头,完。

以上这篇Pyspider中给爬虫伪造随机请求头的实例就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持脚本之家。


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