application/x-www-form-urlencoded

form数据被编码为名称/值对。这是标准的编码格式。

即: form数据会被encode成键值对id=123&name='xiaoming' , 与url通过?拼接.
转义:

• 空格转义为+ ;
• 保留字符转移参见RFC1738的第2.2节;
• 非字母数字字符替换为%HH, 即对应的ascii的十六进制形式;
• 换行字符CRLF 转义为 %0D%0A

• 名称与值通过=连接, 名称值对之间使用&连接.

  
  
  图片.png

参见: https://www.w3.org/TR/html401/interact/forms.html#h-17.13.4

对于python3 , 使用urllib3时, 需要使用 from urllib.parse import urlencode , encoded_args = urlencode(startfields)

application/json

使用json的特点是, post的数据可以有层级嵌套结构 .
后台需要使用 @RequestBody 注解来获取.
前端发送时, 像urllib3 , 需要进行json编码然后放到body中,

>>> import json
>>> data = {'attribute': 'value'}
>>> encoded_data = json.dumps(data).encode('utf-8')
>>> r = http.request(
...     'POST',
...     'http://httpbin.org/post',
...     body=encoded_data,
...     headers={'Content-Type': 'application/json'})
>>> json.loads(r.data.decode('utf-8'))['json']
{'attribute': 'value'}

multipart/form-data

用来上传包含文件, non-ascii数据和二进制数据的表单.
在表单中使用Content-Dispositon 来进行分割表单的各个部分 :

The following example illustrates "multipart/form-data" encoding. Suppose we have the following form:

 <FORM action="http://server.com/cgi/handle"
       enctype="multipart/form-data"
       method="post">
   <P>
   What is your name? <INPUT type="text" name="submit-name"><BR>
   What files are you sending? <INPUT type="file" name="files"><BR>
   <INPUT type="submit" value="Send"> <INPUT type="reset">
 </FORM>
If the user enters "Larry" in the text input, and selects the text file "file1.txt", the user agent might send back the following data:

   Content-Type: multipart/form-data; boundary=AaB03x

   --AaB03x
   Content-Disposition: form-data; name="submit-name"

   Larry
   --AaB03x
   Content-Disposition: form-data; name="files"; filename="file1.txt"
   Content-Type: text/plain

   ... contents of file1.txt ...
   --AaB03x--
If the user selected a second (image) file "file2.gif", the user agent might construct the parts as follows:

   Content-Type: multipart/form-data; boundary=AaB03x

   --AaB03x
   Content-Disposition: form-data; name="submit-name"

   Larry
   --AaB03x
   Content-Disposition: form-data; name="files"
   Content-Type: multipart/mixed; boundary=BbC04y

   --BbC04y
   Content-Disposition: file; filename="file1.txt"
   Content-Type: text/plain

   ... contents of file1.txt ...
   --BbC04y
   Content-Disposition: file; filename="file2.gif"
   Content-Type: image/gif
   Content-Transfer-Encoding: binary

   ...contents of file2.gif...
   --BbC04y--
   --AaB03x--