Time Module additional knowledge
What date and datetime difference is?
date 就是年月日
datetime就是年月时时分秒
The following code will complain Why?
import json
from datetime import datetime,date
print(datetime.today())
print(date.today())
"""
TypeError: Object of type 'datetime' is not JSON serializable
"""becausedatetime 和 data所传出的类型并不是json默认能处理的 不能被json序列化
principlejson 处理数据类型用的类是JSONEcoder 你不往dumps里面传cls的类 他就默认用JSONEcoder
JSONEcoder这个类的方法default 定义了他不能序列化时返回的内容
You can write a class to inherit their own JSONEcoder, and override the default method which
class MyJson(json.JSONEncoder):
def default(self, o):
if isinstance(o,datetime):
return o.strftime('%Y-%m-%d %X')
elif isinstance(o,date):
return o.strftime('%Y-%m-%d')
else:
return super().default(self,o)
res = {'c1':datetime.today(),'c2':date.today()}
print(json.dumps(res,cls=MyJson))
# {"c1": "2019-08-06 20:38:50", "c2": "2019-08-06"}The default method rewritten not only make the process json datetime.todat () and date.today ()
You can control the output in the form specified
network programming
Software development framework
c / s architecture (client / server)
c: Client
s: server
b / s architecture (browser / server)
b: Browser
s: server
ps: b / s architecture essentials is c / s architecture
Mobile terminal looks c / s architecture (ie client installed on the phone) more fire, in fact, b / s (ie the end of the phone APP acts as a browser, all service on the web page) has been rising.
Micro-channel Alipay are doing one thing: a unified interface
It is foreseeable that after the end of the phone is certainly the b / s more fire.
Service and client characteristics?
Server: 24-hour service
Client: When did want to experience the service, went corresponding server to request service
What learning network programming use, and the development of a b / s architecture software needs?
Learning Network programming can develop a c / s architecture software
Concurrency, database front-end, Django can develop a b / s architecture software
History of network programming
The earliest any advanced technology are derived from military
return to the past
- Early telephone phone line
- Big ass Internet line
- Laptop wireless phone
To achieve remote first need is: a physical connection media
People have to say in order to achieve smooth communication unified language
>>> 英文
To communicate between the remote computer and the computer is connected in addition to the physical medium further need
>>> 一套公共的标准/协议
Osi seven agreements
应表会传网数物
Application layer
Presentation layer
Session Layer
Transport Layer
Network layer
data link layer
Physical connection layer
Osi五层协议
Application layer
Transport Layer
Network layer
data link layer
Physical connection layer
1. The physical connection layer
010101 binary data based on the electrical signal transmission
2. Data Link Layer
a. predetermined electrical signal the grouping
b. any Internet-connected computer must have a network card
Each piece of card is engraved with a unique number in the world
12 hexadecimal
The top six vendors No.
After six line number
This 12-digit called mac address
ps: the above two points collectively referred to as "Ethernet protocol"
Switch
Ethernet-based communication protocols
can not communicate across local area networks
3. Network Layer
IP protocol
As long as the provisions of the computers connected to the Internet must have an IP address
ip address Features: dotted decimal
ip address minimum: 0.0.0.0
ip address maximum: 255.255.255.255
ip address There are two versions: IPV4 IPV6(Because not enough that the current IPV4 so there is a computer version launched IPV6)
IP地址是动态分配的
4. Transport Layer
Protocol TCP \ UDP port is based on the work of the
port (port)
In fact, between the computer and the computer is the communication between applications on the computer with the application
Port: An identifier for a computer on an application
range of port numbers: 0 to 65535
Note: 0 to 1024. These are the operating system default port number used
Recommendation: Use the port after the 8000
MySQL default port: 3306
Redis default port: 6379
Django default port: 8000
the Flask default port: 5000
The port number is dynamically assigned
for the first time since 8989 is assigned to qq
will start again qq closed port number might have changed
Summary
ip地址: An identifier for a computer to access the Internet
port端口: An identifier for an application on a computer
ip+port: uniquely identifies an application to access the Internet on a computer
The application layer
HTTP protocol
FTP protocol
TCP protocol
Streaming protocol, reliable protocol
TCP-based protocol channel
The reason why the TCP protocol to transmit data reliably, it is the use of two-way channel
Four waving three-way handshake
Three-way handshake to establish a connection
Four waving Disconnect
