Python网络编程基础
网络编程基础概念
计算机网络架构
计算机网络由独立设备互联构成，核心目标是实现设备间通信和资源共享。现代网络包含海量设备和用户，形成复杂系统架构。
TCP/IP协议栈
网络通信基于标准化协议，TCP/IP模型将网络功能分为四层：
- 网络接口层 - 物理连接
- 网络层 - IP寻址路由
- 传输层 - 端到端传输控制
- 应用层 - 应用程序服务
IP协议实现设备寻址和路由选择，TCP协议提供可靠传输保障：
- 数据完整性校验
- 滑动窗口流量控制
- 拥塞避免机制
应用架构模式
- 客户端/服务器模式(C/S)
- 浏览器/服务器模式(B/S)
- 分布式对等网络(P2P)
HTTP协议应用开发
HTTP核心机制
HTTP协议支持客户端与服务器的资源交互，通过URI定位网络资源，采用请求-响应通信模式。
JSON数据交换
JSON格式轻量高效，适用于跨平台数据交换：
{
"origin": "Alice",
"destination": "Bob",
"message": "Meeting at 3PM"
}HTTP请求库应用
import requests
from concurrent.futures import ThreadPoolExecutor
def fetch_image(url, save_path):
response = requests.get(url)
with open(save_path, 'wb') as file:
file.write(response.content)
def fetch_image_urls(api_endpoint):
response = requests.get(api_endpoint)
return [item['url'] for item in response.json()['results']]
if __name__ == "__main__":
api_url = "https://api.example.com/images?count=5"
image_urls = fetch_image_urls(api_url)
with ThreadPoolExecutor() as executor:
for idx, url in enumerate(image_urls):
executor.submit(fetch_image, url, f"image_{idx}.jpg")传输层套接字编程
TCP套接字服务端
from socket import socket, AF_INET, SOCK_STREAM
from datetime import datetime
def start_tcp_server(host, port):
server_socket = socket(AF_INET, SOCK_STREAM)
server_socket.bind((host, port))
server_socket.listen(5)
while True:
client, addr = server_socket.accept()
current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
client.send(current_time.encode())
client.close()TCP套接字客户端
from socket import socket
def connect_to_server(host, port):
client_socket = socket()
client_socket.connect((host, port))
response = client_socket.recv(1024)
print("Server response:", response.decode())
client_socket.close()文件传输实现
# 服务端
import socket
import json
from base64 import b64encode
from threading import Thread
class FileSender(Thread):
def __init__(self, connection):
super().__init__()
self.conn = connection
def run(self):
with open('example.jpg', 'rb') as file:
encoded_data = b64encode(file.read()).decode()
payload = {'filename': 'example.jpg', 'data': encoded_data}
self.conn.send(json.dumps(payload).encode())
self.conn.close()
def start_file_server(port):
server = socket.socket()
server.bind(('0.0.0.0', port))
server.listen()
while True:
client, _ = server.accept()
FileSender(client).start()# 客户端
import json
import socket
from base64 import b64decode
def receive_file(host, port):
client_socket = socket.socket()
client_socket.connect((host, port))
received = b''
while True:
segment = client_socket.recv(1024)
if not segment: break
received += segment
file_info = json.loads(received.decode())
with open(file_info['filename'], 'wb') as file:
file.write(b64decode(file_info['data'].encode()))
print("File received successfully")UDP协议特性
UDP提供轻量级无连接传输服务，适用于实时性要求高于数据完整性的场景，如音视频流传输。
