python爬虫headers设置后无效的解决方法

此次遇到的是一个函数使用不熟练造成的问题，但有了分析工具后可以很快定位到问题（此处推荐一个非常棒的抓包工具fiddler） 

正文如下：

在爬取某个app数据时（app上的数据都是由http请求的），用Fidder分析了请求信息，并把python的request header信息写在程序中进行请求数据

代码如下

import requests
url = 'http://xxx?startDate=2017-10-19&endDate=2017-10-19&pageIndex=1&limit=50&sort=datetime&order=desc'

headers={
 "Host":"xxx.com",
 "Connection": "keep-alive",
 "Accept": "application/json, text/javascript, */*; q=0.01",
 "User-Agent": "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.59 Safari/537.36",
 "X-Requested-With": "XMLHttpRequest",
 "Referer": "http://app.jg.eastmoney.com/html_Report/index.html",
 "Accept-Encoding": "gzip,deflate",
 "Accept-Language": "en-us,en",
 "Cookie":"xxx"
}
r = requests.get(url,headers)
print (r.text)

请求成功但是，返回的是

{"Id":"6202c187-2fad-46e8-b4c6-b72ac8de0142","ReturnMsg":"加载失败！"}

就是被发现不是正常请求被拦截了

然后我去Fidder中看刚才python发送请求的记录 #盖掉的两个部分分别是Host和URL。

然后查看请求详细信息的时候，请求头并没有加载进去，User-Agent就写着python-requests !   #请求头里的UA信息是java，python程序，有点反爬虫意识的网站、app都会拦截掉

Header详细信息如下

GET http://xxx?istartDate=2017-10-19&endDate=2017-10-19&pageIndex=1&limit=50&sort=datetime&order=desc
　　&Host=xxx.com
　　&Connection=keep-alive
　　&Accept=application%2Fjson%2C+text%2Fjavascript%2C+%2A%2F%2A%3B+q%3D0.01
　　&User-Agent=Mozilla%2F5.0+%28Windows+NT+6.1%3B+WOW64%29+AppleWebKit%2F537.36+%28KHTML%2C+like+Gecko%29+Chrome%2F29.0.1547.59+Safari%2F537.36
　　&X-Requested-With=XMLHttpRequest
　　&Referer=xxx
　　&Accept-Encoding=gzip%2Cdeflate
　　&Accept-Language=en-us%2Cen
　　&Cookie=xxx
HTTP/1.1


Host: xxx.com
User-Agent: python-requests/2.18.4
Accept-Encoding: gzip, deflate
Accept: */*
Connection: keep-alive


HTTP/1.1 200 OK
Server: nginx/1.2.2
Date: Sat, 21 Oct 2017 06:07:21 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 75
Connection: keep-alive
Cache-Control: private
X-AspNetMvc-Version: 5.2
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET

一开始还没发现，等我把请求的URL信息全部读完，才发现程序把我的请求头信息当做参数放到了URL里

那就是我请求的时候request函数Header信息参数用错了

又重新看了一下Requests库的Headers参数使用方法，发现有一行代码写错了，在使用request.get（）方法时要把参数 “headers =“写出来 

更改如下：

import requests
url = 'http://xxx?startDate=2017-10-19&endDate=2017-10-19&pageIndex=1&limit=50&sort=datetime&order=desc'

headers={
 "Host":"xxx.com",
 "Connection": "keep-alive",
 "Accept": "application/json, text/javascript, */*; q=0.01",
 "User-Agent": "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.59 Safari/537.36",
 "X-Requested-With": "XMLHttpRequest",
 "Referer": "http://app.jg.eastmoney.com/html_Report/index.html",
 "Accept-Encoding": "gzip,deflate",
 "Accept-Language": "en-us,en",
 "Cookie":"xxx"
}
r = requests.get(url,headers=headers)

然后去查看Fiddler中的请求。

此次python中的请求头已经正常了，请求详细信息如下

GET http://xxx?startDate=2017-10-19&endDate=2017-10-19&pageIndex=1&limit=50&sort=datetime&order=desc HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.59 Safari/537.36
Accept-Encoding: gzip,deflate
Accept: application/json, text/javascript, */*; q=0.01
Connection: keep-alive
Host: xxx.com
X-Requested-With: XMLHttpRequest
Referer: http://xxx
Accept-Language: en-us,en
Cookie: xxx


HTTP/1.1 200 OK
Server: nginx/1.2.2
Date: Sat, 21 Oct 2017 06:42:21 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 75
Connection: keep-alive
Cache-Control: private
X-AspNetMvc-Version: 5.2
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET

然后又用python程序请求了一次，结果请求成功，返回的还是

{"Id":"6202c187-2fad-46e8-b4c6-b72ac8de0142","ReturnMsg":"加载失败！"} 

因为一般cookie都会在短时间内过期，所以更新了cookie，然后请求成功

需要注意的是用程序爬虫一定要把Header设置好，这个app如果反爬的时候封ip的话可能就麻烦了。

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