HTTP协议中没有规定post提交的数据必须使用什么编码方式，服务端根据请求头中的Content-Type字段来获取编码方式，再对数据进行解析。具体的编码方式包括如下：

- application/x-www-form-urlencoded # 以form表单形式提交数据，最常见最熟悉

- application/json # 以json串提交数据。

- multipart/form-data # 上传文件

下面使用requests来发送上述三种编码的POST请求。

1、提交Form表单

requests提交Form表单,一般存在于网站的登录，用来提交用户名和密码。以 http://httpbin.org/post 为例，在requests中，以form表单形式发送post请求，只需要将请求的参数构造成一个字典，然后传给requests.post()的data参数即可。(httpbin.org 网站可以显示提交请求的内容，输出的”Content-Type”:”application/x-www-form-urlencoded”,证明这是提交Form的方式。)代码如下：

# -*- coding: utf-8 -*-

import requests

def get_html(url, key_value, retry=2):

try:

r = requests.post(url=url, headers=headers, data=key_value, timeout=5)

except Exception as e:

print(e)

if retry > 0:

get_html(url, retry - 1)

else:

page = r.text

return page

if __name__ == "__main__":

# 自定义请求头信息

headers = {

'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36',

}

url = 'http://httpbin.org/post'

kw = {'wd': 'www.python66.com'}

html = get_html(url, kw)

print(html)

D:python3installpython.exe D:/python/py3script/test.py

{

"args": {},

"data": "",

"files": {},

"form": {

"wd": "www.python66.com"

},

"headers": {

"Accept": "*/*",

"Accept-Encoding": "gzip, deflate",

"Content-Length": "19",

"Content-Type": "application/x-www-form-urlencoded",

"Host": "httpbin.org",

"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36"

},

"json": null,

"origin": "223.72.81.198, 223.72.81.198",

"url": "https://httpbin.org/post"

}

Process finished with exit code 0

2、提交json串

对于提交json串(浏览器中抓包显示payload)，主要是用于发送ajax请求中，动态加载数据。

可以用json.dumps()对dict进行编码，可以使用json参数直接传递，然后它就会被自动编码,在请求头中也不用显示声明 这是 2.4.2 版的新加功能。代码如下：

# -*- coding: utf-8 -*-

import requests

import json

def get_html(url, key_value, retry=2):

try:

r = requests.post(url=url, headers=headers, data=key_value, timeout=5)

except Exception as e:

print(e)

if retry > 0:

get_html(url, retry - 1)

else:

page = r.text

return page

def get_html_json(url, key_value, retry=2):

try:

r = requests.post(url=url, headers=headers, json=key_value, timeout=5)

except Exception as e:

print(e)

if retry > 0:

get_html_json(url, retry - 1)

else:

page = r.text

return page

if __name__ == "__main__":

# 自定义请求头信息

headers = {

'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36',

'Content-Type':'application/json; charset=UTF-8',

}

url = 'https://api.xxxx.com/xxx/xxx'

kw = {'domain': 'www.python66.com'}

# json.dumps

html = get_html(url, json.dumps(kw))

# 传递json参数

html_json = get_html_json(url,kw)

3.上传文件：

上传文件在爬虫中使用的很少。Content-Type类型为multipart/form-data，以multipart形式发送post请求，只需将一文件传给 requests.post() 的 files参数即可。还是以 http://httpbin.org/post 为例，代码如下：

# -*- coding: utf-8 -*-

import requests

def get_html(url, key_value, retry=2):

try:

r = requests.post(url=url, headers=headers, data=key_value, timeout=5)

except Exception as e:

print(e)

if retry > 0:

get_html(url, retry - 1)

else:

page = r.text

return page

if __name__ == "__main__":

# 自定义请求头信息

headers = {

'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36',

}

url = 'http://httpbin.org/post'

files = {'file': open('ajax.png', 'rb')}

html = get_html(url, files)

print(html)

D:python3installpython.exe D:/python/py3script/test.py

{

"args": {},

"data": "",

"files": {

"file": "data:application/octet-stream;base64,...太长..省略..."

},

"form": {},

"headers": {

"Accept": "*/*",

"Accept-Encoding": "gzip, deflate",

"Content-Length": "68870",

"Content-Type": "multipart/form-data; boundary=66f5b203f18f79960ac438c59af481b0",

"Host": "httpbin.org",

"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36"

},

"json": null,

"origin": "223.72.72.67, 223.72.72.67",

"url": "https://httpbin.org/post"

}

Process finished with exit code 0

警告

建议用二进制模式(binary mode)打开文件，因为 Requests 可能会试图为你提供 Content-Length header，在它这样做的时候，这个值会被设为文件的字节数(bytes)。如果用文本模式(text mode)打开文件，就可能会发生错误。