Python实战笔记(二) 网络编程

Python 提供 socket 模块用于访问网络服务，使得不同主机之间的进程可以相互通信

1、创建 Socket 对象

socket.socket([family[, type[, proto]]])

• family：套接字家族，一般取值如下：
  • socket.AF_INET：不同主机上的网络通信，使用 IPV4 协议
  • socket.AF_INET6：不同主机上的网络通信，使用 IPV6 协议
  • socket.AF_UNIX：同一主机上的进程通信
• type：套接字类型，一般取值如下：
  • socket.SOCK_STREAM：流套接字，用于 TCP 通信
  • socket.SOCK_DGRAM：数据报套接字，用于 UDP 通信
  • socket.SOCK_RAW：原始套接字，用于处理 ICMP、IGMP 等特殊的网络报文
• proto：协议编号，默认为 0

2、Socket 对象的常用方法

（1）服务端的常用方法

• bind(address) ：绑定地址到套接字，address 表示通信地址，格式取决于使用的套接字家族
• listen(backlog)：监听连接，backlog 表示在拒绝连接前可以挂起的最大连接数量
• accept()：接受连接，返回 (connect, address)，connect 是新的 Socket 对象，用来接收和发送数据

（2）客户端的常用方法

• connect(address)：连接到指定地址的套接字，如果连接出错，返回 socket.error
• connect_ex(address)：连接到指定地址的套接字，如果连接出错，返回错误编码

（3）公共用途常用方法

• recv(bufsize[,flag])：从套接字接收数据，一般用于 TCP 协议，返回接收到的数据
• recvfrom(bufsize[.flag])：从套接字接收数据，一般用于 UDP 协议，返回接收到的数据和发送方的地址
• send(data[,flag])：发送数据到套接字，一般用于 TCP 协议，返回发送的字节数
• sendall(data[,flag])：完整发送数据到套接字，成功则返回 None，失败则抛出异常
• sendto(data[,flag], address)：发送数据到套接字，一般用于 UDP 协议，返回发送的字节数
• close()：关闭套接字
• getsockname()：返回连接套接字的己方地址
• getpeername()：返回连接套接字的远程地址
• setsockopt(level,optname,value)：设置套接字选项的值
• getsockopt(level,optname)：获取套接字选项的值
• settimeout(timeout)：设置套接字的超时值，timeout 表示超时时间，单位为秒
• gettimeout()：获取套接字的超时值，如果没有设置超时时间，返回 None

3、例子

（1）客户端传输数据到服务端

• server.py

import socket
import threading

def create_service():
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    address = ('127.0.0.1', 8888)
    server.bind(address)
    server.listen(5)
    print('Waiting connection ...')
    while True:
        conn, addr = server.accept()
        thread = threading.Thread(target = handle_request, args = (conn, addr))
        thread.start()
    server.close()

def handle_request(conn, addr):
    print('Accept connection from', addr)
    while True:
        recv_byte = conn.recv(1024)
        recv_data = recv_byte.decode('UTF-8')
        print(recv_data)
        if recv_data == 'quit': break
    conn.close()

if __name__ == '__main__':
    create_service()

• client.py

import socket

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
address = ('127.0.0.1', 8888)
client.connect(address)
print('Connect to', address)

while True:
    send_data = input('Please Enter Something: ')
    send_byte = send_data.encode('UTF-8')
    client.send(send_byte)
    if send_data == 'quit': break

client.close()

（2）客户端从服务端下载文件

• server.py

import socket
import threading
import os
import json

def create_service():
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    address = ('127.0.0.1', 8888)
    server.bind(address)
    server.listen(5)
    print('Waiting connection ...')
    while True:
        conn, addr = server.accept()
        thread = threading.Thread(target = handle_request, args = (conn, addr))
        thread.start()
    server.close()

def handle_request(conn, addr):
    print('Accept connection from', addr)
    while True:
        file_name = conn.recv(1024).decode('UTF-8')
        print('Request File:', file_name)
        if not os.path.exists(file_name):
            message = 'Not Exist'
            print(message)
            conn.send(message.encode('UTF-8'))
        else:
            real_name = os.path.split(file_name)[1]
            file_size = os.path.getsize(file_name)
            file_info = json.dumps({
                'real_name': real_name,
                'file_size': file_size
            })
            conn.send(file_info.encode('UTF-8'))
            conn.recv(1024)
            print('Send File ...')
            with open(file_name, 'rb') as file:
                for line in file:
                    conn.send(line)
                print('Send File Successful')
    conn.close()

if __name__ == '__main__':
    create_service()

• client.py

import socket
import os
import json

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
address = ('127.0.0.1', 8888)
client.connect(address)
print('Connect to', address)

while True:
    file_name = input('Please Enter File Name: ')
    client.send(bytes(file_name, encoding='UTF-8'))
    recv_data = client.recv(1024).decode('UTF-8')
    if recv_data == 'Not Exist':
        print(recv_data)
    else:
        file_info = json.loads(recv_data)
        real_name = file_info['real_name']
        file_size = file_info['file_size']
        client.send(bytes('Received', encoding='UTF-8'))
        print('Receive File ...')
        recv_size = 0
        with open(real_name, 'wb') as file:
            while recv_size < file_size:
                chunk = client.recv(1024)
                file.write(chunk)
                recv_size += len(chunk)
            print('Receive File Successful')

client.close()

（3）客户端上传文件到服务端

• server.py

import socket
import threading
import os
import json

def create_service():
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    address = ('127.0.0.1', 8888)
    server.bind(address)
    server.listen(5)
    print('Waiting connection ...')
    while True:
        conn, addr = server.accept()
        thread = threading.Thread(target = handle_request, args = (conn, addr))
        thread.start()
    server.close()

def handle_request(conn, addr):
    print('Accept connection from', addr)
    while True:
        recv_data = conn.recv(1024).decode('UTF-8')
        file_info = json.loads(recv_data)
        real_name = file_info['real_name']
        file_size = file_info['file_size']
        conn.send(bytes('Received', encoding='UTF-8'))
        print('Receive File ...')
        recv_size = 0
        with open(real_name, 'wb') as file:
            while recv_size < file_size:
                chunk = conn.recv(1024)
                file.write(chunk)
                recv_size += len(chunk)
            print('Receive File Successful')
    conn.close()

if __name__ == '__main__':
    create_service()

• client.py

import socket
import os
import json

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
address = ('127.0.0.1', 8888)
client.connect(address)
print('Connect to', address)

while True:
    file_name = input('Please Enter File Name: ')
    if not os.path.exists(file_name):
        print('Not Exist')
        continue
    real_name = os.path.split(file_name)[1]
    file_size = os.path.getsize(file_name)
    file_info = json.dumps({
        'real_name': real_name,
        'file_size': file_size
    })
    client.send(file_info.encode('UTF-8'))
    client.recv(1024)
    print('Send File ...')
    with open(file_name, 'rb') as file:
        for line in file:
            client.send(line)
        print('Send File Successful')

client.close()

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