利用网络编程实现一台服务器对多台客户机实现上传和下载功能

要实现一台服务器对多台客户机实现上传和下载功能，可以使用网络编程中的Socket套接字来实现。下面是一个简单的示例代码：

服务器端：

import socket
import threading
import os

def handle_client(client_socket, address):
    print(f"New connection from {address}")
    
    # 接收客户端请求
    request = client_socket.recv(1024).decode()
    
    # 判断客户端请求类型
    if request == "upload":
        handle_upload(client_socket)
    elif request == "download":
        handle_download(client_socket)
    
    client_socket.close()
    print(f"Connection from {address} closed")

def handle_upload(client_socket):
    # 接收上传文件名
    filename = client_socket.recv(1024).decode()
    
    # 接收文件内容并保存
    with open(filename, "wb") as file:
        while True:
            data = client_socket.recv(1024)
            if not data:
                break
            file.write(data)
    
    print(f"Upload complete: {filename}")

def handle_download(client_socket):
    # 接收下载文件名
    filename = client_socket.recv(1024).decode()
    
    # 判断文件是否存在
    if not os.path.exists(filename):
        client_socket.send(b"File not found")
        return
    
    # 发送文件内容
    with open(filename, "rb") as file:
        while True:
            data = file.read(1024)
            if not data:
                break
            client_socket.send(data)
    
    print(f"Download complete: {filename}")

def start_server():
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.bind(("127.0.0.1", 8888))
    server_socket.listen(5)
    print("Server started, listening on port 8888")
    
    while True:
        client_socket, address = server_socket.accept()
        client_thread = threading.Thread(target=handle_client, args=(client_socket, address))
        client_thread.start()

start_server()

客户端：

import socket

def upload_file(filename):
    client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    client_socket.connect(("127.0.0.1", 8888))
    
    # 发送请求类型
    client_socket.send(b"upload")
    
    # 发送上传文件名
    client_socket.send(filename.encode())
    
    # 发送文件内容
    with open(filename, "rb") as file:
        while True:
            data = file.read(1024)
            if not data:
                break
            client_socket.send(data)
    
    print(f"Upload complete: {filename}")

def download_file(filename):
    client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    client_socket.connect(("127.0.0.1", 8888))
    
    # 发送请求类型
    client_socket.send(b"download")
    
    # 发送下载文件名
    client_socket.send(filename.encode())
    
    # 接收文件内容并保存
    with open(filename, "wb") as file:
        while True:
            data = client_socket.recv(1024)
            if not data:
                break
            file.write(data)
    
    print(f"Download complete: {filename}")

# 示例代码中假设客户端与服务器在同一台机器上，并使用本地回环地址 127.0.0.1 和端口号 8888。
# 若要连接不同机器上的服务器，请将服务器地址和端口号修改为正确的值。

# 上传文件示例
upload_file("file.txt")

# 下载文件示例
download_file("file.txt")

以上代码是一个简单的实现，具体根据需求可以进行进一步的优化和完善。注意要确保服务器和客户端的地址和端口号一致，并根据实际情况修改代码中的文件名和路径。