Pyspider中给爬虫伪造随机请求头的实例

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 11:52:26import randomimport timeclass 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