Python之Headers value 1 must be of type str or bytes, not <class 'int'>错误的解决

1. 问题的提出
   在代码中，忽然碰到了如下错误：
'2017-04-25 13:15:13 PM' HttpUtil.py[line:30] ERROR HttpUtil:Header value 1 must be of type str or bytes, not <class 'int'>   使用的代码如下：

response = requests.get(url, headers=headers, cookies=cookies)

  主体的代码是使用requests进行Http的页面调用访问。    引入import traceback来打印错误信息， 在异常捕获部分添加traceback的打印语句：
traceback.print_exc()   其将详细的异常栈打印到控制台上去。

Traceback (most recent call last):
File "/usr/local/python3/lib/python3.6/multiprocessing/process.py", line 249, in _bootstrap
self.run()
File "/usr/local/python3/lib/python3.6/multiprocessing/process.py", line 93, in run
self._target(*self._args, **self._kwargs)
File "/opt/crawler/web-crawler/dyproxy/IPProxyPool/spider/ProxyCrawl.py", line 34, in startProxyCrawl
crawl.run()
File "/opt/crawler/web-crawler/dyproxy/IPProxyPool/spider/ProxyCrawl.py", line 49, in run
parserList = self.urltaker.parse_list()
File "/opt/crawler/web-crawler/dyproxy/IPProxyPool/spider/urls/URLRetriever.py", line 35, in parse_list
site_config['urls'] = getattr(self, 'retrieve_' + site.xpath("@name")[0])(site.xpath("@url")[0], site.xpath('./setting/@url')[0])
File "/opt/crawler/web-crawler/dyproxy/IPProxyPool/spider/urls/URLRetriever.py", line 110, in retrieve_mimiip
response = HttpUtil.get(site_url % proxy, headers=all_headers['mimiip'])
File "/opt/crawler/web-crawler/dyproxy/IPProxyPool/util/HttpUtil.py", line 31, in get
traceback.print_exc()
File "/usr/local/python3/lib/python3.6/traceback.py", line 159, in print_exc
print_exception(*sys.exc_info(), limit=limit, file=file, chain=chain)
File "/usr/local/python3/lib/python3.6/traceback.py", line 101, in print_exception
print(line, file=file, end="")

  基本确定就是headers或者cookies的问题。

2.  问题分析
     基于错误信息，感觉是headers中的数据类型问题，期望string，但是实际上是int类型。经过检查发现是在自定义的header中：
"mimiip": {
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
"Accept-Encoding":"gzip, deflate",
"Accept-Language":"zh-CN,zh;q=0.8,de;q=0.6,en;q=0.4,zh-TW;q=0.2",
"Cache-Control":"Max-Age=0",
"Connection":"keep-alive",
"DNT":1,
"Host":"www.mimiip.com",
"Referer":"http://www.mimiip.com/gngao/",
"If-None-Match":"169bceb52ed4a052e3b0f82bda5b0462",
"Upgrade-Insecure-Requests"：1,
"User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3063.4 Safari/537.36"
}  其中使用了两个数字类型的，估计应该是这个位置的问题。
3.   问题解决    将上述中的int类型的数据，修改为string类型，则可以正常访问。

4.  总结
      在Http请求中，所有的都是字符串，没有数字类型的，尤其是在构建的请求中，请注意这个问题。