实现TCP

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import socket

# 创建一个socket:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 建立连接:
s.connect(('www.sina.com.cn', 80))

# 发送数据:
s.send(b'GET / HTTP/1.1\r\nHost: www.sina.com.cn\r\nConnection: close\r\n\r\n')

# 接收数据:
buffer = []
while True:
    # 每次最多接收1k字节:
    d = s.recv(1024)
    if d:
        buffer.append(d)
    else:
        break

data = b''.join(buffer)

# 关闭连接:
s.close()

header, html = data.split(b'\r\n\r\n', 1)
print(header.decode('utf-8'))

# 把接收的数据写入文件:
with open('sina.html', 'wb') as f:
    f.write(html)

实现UDP连接

服务端：
#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# 绑定端口:
s.bind(('127.0.0.1', 9999))

print('Bind UDP on 9999...')

while True:
    # 接收数据:
    data, addr = s.recvfrom(1024)
    print('Received from %s:%s.' % addr)
    reply = 'Hello, %s!' % data.decode('utf-8')
    s.sendto(reply.encode('utf-8'), addr)

客户端：
#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

for data in [b'Michael', b'Tracy', b'Sarah']:
    # 发送数据:
    s.sendto(data, ('127.0.0.1', 9999))
    # 接收数据:
    print(s.recv(1024).decode('utf-8'))

s.close()