python网络爬虫

1.可以通过r.headers来获取响应头内容

>>>r = requests.get('http://www.zhidaow.com')
>>> r.headers
{
    'content-encoding': 'gzip',
    'transfer-encoding': 'chunked',
    'content-type': 'text/html; charset=utf-8';
    ...
}
>>> r.headers['Content-Type']
'text/html; charset=utf-8'

>>> r.headers.get('content-type')

'text/html; charset=utf-8'

  2.设置超时时间

  >>> requests.get('http://github.com', timeout=0.001)

3.代理访问 

proxies = {
  "http": "http://10.10.1.10:3128",
  "https": "http://10.10.1.10:1080",
}

requests.get("http://www.zhidaow.com", proxies=proxies)

   如果代理需要账户和密码，则需这样：

proxies = {
    "http": "http://user:pass@10.10.1.10:3128/",
}

4.不允许重定向的设置

>>>r = requests.get('http://www.baidu.com/link?url=QeTRFOS7TuUQRppa0wlTJJr6FfIYI1DJprJukx4Qy0XnsDO_s9baoO8u1wvjxgqN', allow_redirects = False)

5. 上传文件

>>> url = 'http://httpbin.org/post'
>>> files = {'file': open('report.xls', 'rb')}

>>> r = requests.post(url, files=files)
>>> r.text
{
  ...
  "files": {
    "file": "<censored...binary...data>"
  },
  ...
}

   还可以显式地设置文件名:

>>> url = 'http://httpbin.org/post'
>>> files = {'file': ('report.xls', open('report.xls', 'rb'))}

>>> r = requests.post(url, files=files)
>>> r.text
{
  ...
  "files": {
    "file": "<censored...binary...data>"
  },
  ...
}

  如果你想，你也可以发送作为文件来接收的字符串:

>>> url = 'http://httpbin.org/post'
>>> files = {'file': ('report.csv', 'some,data,to,send\nanother,row,to,send\n')}

>>> r = requests.post(url, files=files)
>>> r.text
{
  ...
  "files": {
    "file": "some,data,to,send\\nanother,row,to,send\\n"
  },
  ...
}