内容概要
- 如何构建GET 与 POST request 请求消息
- 对 request 的header , query string, message body 定制化
- http header参数 content-type 的设置
- 分析request, response 消息数据
- 通过POST请求上传文件
- 请求与响应使用 json 格式
用 python 编写 http request 消息代码时,建议用requests库。因为requests比urllib内置库更为简捷,requests可以直接构造get,post请求并发送,而urllib.request只能先构造get,post请求消息内容,然后再发送。并且requests 模块提供了更友好的方法与属性来解析response消息内容。
http协议是基于1种客户机(client) – 服务器(server) 的通信模式,它的下层是TCP协议。
客户端发送一个HTTP请求到服务器的请求消息由四个部分组成
下图给出了请求报文的一般格式。
上图中,可以看到。Request 请求行第1个字节为请求方法
, 有时也称动词
(verb), 常用的主要有4种方法:GET, POST, PUT, DELETE
。
服务器的响应消息, 也是由4部分组成
状态行、消息报头、空行和响应正文
安装requests 模块非常简单,
pip install requests
用于准备并发送 http get 请求至指定url , 并返回response 对象
requests.get(url, params=None, **kwargs)
**kwargs
: 可选参数,共有12个控制访问的参数url格式:http://host_ip:port/path/add?key1=value1&key2=value2
传参数用字典类型:params={ key1: value1, key2: value2 }
response = requests.get(
'https://api.github.com/search/repositories',
params={'q':'requests+language:python'},
)
可能遇到的问题:
如果参数中包含汉字 ,则会报编码错误,
可先进行编码, (将utf-8转为ascii码 )
urllib.parse.urlencode(dic)
解码:
urllib.parse.unquote(dic or str)
# 例1
keyword = input('请输入搜索关键字:')
param_list = urllib.parse.urlencode( { 'wd' : keyword } )
header = {'user-Agent':’haha‘}
url = 'http://www.baidu.com/s/'
response = request.get( url, params=param_list, headers = header )
# 例2
headers = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36"}
request.get("http://www.baidu.com",headers=headers)
cookies = {"name":"haha"}
request.get("http://www.baidu.com",cookie=cookies)
收到response后,需要分析 status_code,有必要可以对404, 500等出错响应进行特殊处理。
import requests
from requests.exceptions import HTTPError
for url in ['https://api.github.com', 'https://api.github.com/invalid']:
try:
response = requests.get(url)
# If the response was successful, no Exception will be raised
response.raise_for_status()
except HTTPError as http_err:
print(f'HTTP error occurred: {http_err}') # Python 3.6
except Exception as err:
print(f'Other error occurred: {err}') # Python 3.6
else:
print('Success!')
当调用 .raise_for_status()
, 对特定的status_code将产生1个 HTTPError
异常
Status_code
S.N. | Code and Description |
---|---|
1 | 1xx: Informational It means the request was received and the process is continuing. |
2 | 2xx: Success It means the action was successfully received, understood, and accepted. |
3 | 3xx: Redirection It means further action must be taken in order to complete the request. |
4 | 4xx: Client Error It means the request contains incorrect syntax or cannot be fulfilled. |
5 | 5xx: Server Error It means the server failed to fulfill an apparently valid request. |
常用方法
如果响应内 容是json格式,可以用Response.json()方法转换成 dict类型
如果发出request后,收到异常的response, 可以用下面的数据检查 :
>>> response = requests.post('https://httpbin.org/post', json={'key':'value'})
>>> response.request.headers['Content-Type']
'application/json'
>>> response.request.url
'https://httpbin.org/post'
>>> response.request.body
b'{"key": "value"}'
get方法的请求参数是通过 params={ } 方式来传递的。
response = requests.get(
'https://api.github.com/search/repositories',
params={'name': 'Jack','type':'display'},
)
与GET请求不同的是, POST 请求参数是放在 request body 里发送的, 向 request的 response对象传入的数据类型可以是 tuple, dict, json 等。
# 发送字典
post_dict = {'key1': 'value1', 'key2': 'value2'}
# 发送元组
post_tuple = (('key1', 'value1'), ('key1', 'value2'))
# 发送json
post_json = json.dumps({'some': 'data'})
r1 = requests.post("http://httpbin.org/post", data=post_dict)
r2 = requests.post("http://httpbin.org/post", data=post_tuple)
r3 = requests.post("http://httpbin.org/post", data=post_json)
输出: 以Json 格式发送 POST 请求
POST /echo/post/json HTTP/1.1
Authorization: Bearer mt0dgHmLJMVQhvjpNXDyA83vA_Pxh33Y
Accept: application/json
Content-Type: application/json
Content-Length: 85
Host: reqbin.com
{
"Id": 12345,
"Customer": "John Smith",
"Quantity": 1,
"Price": 10.00
}
收到 Response
HTTP/1.1 200 OK
Content-Length: 19
Content-Type: application/json
{"success":"true"}
import requests
# 请求数据
url = 'http://api.shein.com/v2/member/login'
cookie = "token=code_space;"
header = {
"cookie": cookie,
"Accept": "*/*",
"Accept-Encoding": "gzip, deflate, br",
"Accept-Language": "zh-CN,zh;q=0.9",
"Connection": "keep-alive",
"Content-Type": "application/json",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
"AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36"
}
data = {
'user_id': '123456',
'email': '[email protected]'
}
timeout = 0.5
resp = requests.post(url, headers=header, data=data, timeout=timeout)
print(resp.text)
print(type(resp.json()))
客户端可通过POST请求,向服务器上传文件
#形式1
url = 'http://httpbin.org/post'
#定义文件对象
files = {"files":open('test.xls', 'rb')}
response = requests.post(url,files = files)
print(response.text)
#形式2
url ='http://httpbin.org/post'
files = {'file': ('t.xls', open('t.xls', 'rb'), 'application/vnd.ms-excel', {'Expires': '0'})}
r = requests.post(url, files=files)
r.text
#形式3, 发送多个文件
url = 'http://httpbin.org/post'
files = {'file': ('t.csv', 'bb.csv')}
response = requests.post(url, files=files)
response.text
Content-Type 参数告诉客户端,response实际返回数据的资源类型。这个参数在request 与 response中都可能包含,是 response 消息头部非常关键1个参数,也是开发者应该掌握的1个知识点。
语法格式示例 :
Content-Type: text/html; charset=utf-8
Content-Type: multipart/form-data; boundary=something
content-type 格式为: key/value
, 在http协议以及行业内,有很多通用的建议值,最常见的:
application/x-www-form-urlencoded
, 这是提交表单默认的content-type设置, 对应form属性为 enctype.multipart/form-data
, 用于 form 上传文件application/json
传json数据text/csv
传送csvtext/html
传网页text/plain text/xml
传文本image/jpeg
传图片video/mp4
传MP4视频注:
- 如果key 是 text类型,附件是中文,value 加编码类型:
Content-Type: text/html; charset=UTF-8
- 对于"application/x-www-form-urlencoded" 编码,如果两端都是用request编程,则不需要编解码,request 模块会自动完成。
下面是可能遇到的 content-type 的 key/value 列表:
Type | Values |
---|---|
Application | application/javascript application/pdf application/xhtml+xml application/json application/ld+json application/xml application/zip application/x-www-form-urlencoded application/octet-stream : 二进制流数据(如常见的文件下载) |
Audio | audio/mpeg audio/x-ms-wma |audio audio/x-wav |
Image | image/gif image/jpeg image/png image/tiff i mage/vnd.microsoft.icon image/x-icon image/vnd.djvu image/svg+xml |
Multipart | multipart/mixed multipart/alternative multipart/related (using by MHTML (HTML mail).) multipart/form-data |
Text | text/css text/csv text/html text/plain text/xml |
Video | video/mpeg video/mp4 video/quicktime video/x-ms-wmv video/x-msvideo video/x-flv video/webm |
VND | application/vnd.oasis.opendocument.text application/vnd.oasis.opendocument.spreadsheet application/vnd.oasis.opendocument.presentation application/vnd.oasis.opendocument.graphics application/vnd.ms-excel application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/vnd.ms-powerpoint application/vnd.openxmlformats-officedocument.presentationml.presentation application/msword application/vnd.openxmlformats-officedocument.wordprocessingml.document application/vnd.mozilla.xul+xml |
payload 就是通过http Post,get发送的数据,包括请求参数,文件,图片等, 发送方可以将用json类型来准备这些数据,接收方用json解开。
这在Header 里约定好。如下, 但注意,header 不能是json格式。
POST /echo/post/json HTTP/1.1
Host: reqbin.com
Accept: application/json
Content-Type: application/json
Content-Length: 52
{
"Id": 12345
}
response内容也可以用json来发送
{
"success": "true",
"data": {
"TotalOrders": 100
}
}
>>> requests.post('https://httpbin.org/post', data={'key':'value'})
>>> requests.put('https://httpbin.org/put', data={'key':'value'})
>>> requests.delete('https://httpbin.org/delete')
>>> requests.head('https://httpbin.org/get')
>>> requests.patch('https://httpbin.org/patch', data={'key':'value'})
>>> requests.options('https://httpbin.org/get')