Python客户端服务端文件传输代码：目录与登录验证问题求助

核心问题 #

• Windows系统下Python无法识别指定目录，运行时提示目录不存在；
• 基于字典的登录验证系统失效，无论输入何种账号密码均能登录；
• 文件传输的读写逻辑存在错误，导致功能无法正常运行。

客户端代码 #

import socket               # Import socket module
s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345                 # Reserve a port for your service.
x = True

username = input('Username: ')
password = input('Password: ')

Login = {
    "joshua": "macOS", #regardless of information used to login, still logs you in
    "scotto": "linux",
    "divetta": "windows",
    }

print("testing1") #prints but crashes too quickly

print("Successfully Logged In")
s.connect((host, port))
choice = int(input("1=Upload or 2=Download: "))
while x == True:
    if choice == 1:
        print("upload")
        upload = input("File name to upload: ")
        f = open('Client\\{upload}','rb') #ask about how to get folder to work here with filename
        print('Sending...')
        l = f.read(1024) #ask if this will make the file transfer, transfer data
        while (l):
            print('Sending...')
            s.send(l)
            l = f.read(1024)
            x = False
        f.close()
        print("Done Sending")
        s.shutdown(socket.SHUT_WR)
        print(s.recv(1024))
        s.close()
        
elif choice == 2:
        print("download")
        download = input("File name to download: ")
        f = open('Client\\{download}','rb') #ask about how to get folder to work here with filename
        print('Receiving...')
        l = f.write(1024)
        while (l):
            print('Receiving...')
            s.recv(l)
            l = f.write(1024)
            x = False
        f.close()
        print("Done Receiving")
        s.shutdown(socket.SHUT_WR)
        print(s.recv(1024))
        s.close()
        
else:
        print("invalid choice")
        x = True

服务端代码 #

import socket               # Import socket module
s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345                 # Reserve a port for your service.
s.bind((host, port))        # Bind to the port
s.listen(5)                 # Now wait for client connection.
c, addr = s.accept()     # Establish connection with client.
print('Got connection from', addr)

Login = {
    "joshua": "macOS",
    "scotto": "linux",
    "divetta": "windows",
    }

while True:
    l = c.recv(1024)
    while (l):
        print("Receiving...")
        f.write(l)
        l = c.recv(1024)
        f.close()
        print("Done Receiving")
        #c.close()                # Close the connection
while False:
    l = c.send(1024)
    while (l):
        print("Sending...")
        f.read(l)
        l = c.send(1024)
        f.close()
        print("Done Sending")
        #c.close()

问题修复方案 #

1. 登录验证失效修复 #

当前代码未对账号密码做任何校验，直接跳过验证步骤，需添加以下逻辑：

# 替换原有的print("Successfully Logged In")代码块
if Login.get(username) == password:
    print("Successfully Logged In")
    s.connect((host, port))
    # 后续上传/下载逻辑放在这个分支内
else:
    print("Invalid username or password")
    exit()

同时服务端也需要同步验证逻辑：客户端发送账号密码后，服务端校验并返回结果，避免无效连接占用资源。

2. Windows目录识别问题修复 #

• 字符串格式化错误：'Client\\{upload}'未正确替换变量，需改为f-string格式：f'Client\\{upload}'
• 路径兼容性：建议使用os.path模块拼接路径，避免Windows下的转义问题：

import os
# 替换打开文件的代码
file_path = os.path.join("Client", upload)
f = open(file_path, 'rb')

• 文件夹存在性：确保Client文件夹在脚本运行的当前目录下，或使用绝对路径指定位置。

3. 文件传输读写逻辑修复 #

客户端上传逻辑

• 移除循环内的x = False，否则仅发送一次数据就终止循环：

l = f.read(1024)
while l:
    print('Sending...')
    s.send(l)
    l = f.read(1024)
x = False  # 发送完成后再终止外层循环

客户端下载逻辑

• 下载时文件需用'wb'（二进制写入）模式打开，而非'rb'；f.write()需接收socket返回的字节数据，而非传入数字：

download = input("File name to download: ")
file_path = os.path.join("Client", download)
f = open(file_path, 'wb')
print('Receiving...')
l = s.recv(1024)
while l:
    print('Receiving...')
    f.write(l)
    l = s.recv(1024)
f.close()

服务端逻辑

• 未定义文件对象f就调用f.write()，需先接收文件名再创建文件：

# 服务端处理上传示例
while True:
    filename = c.recv(1024).decode()
    if not filename:
        break
    file_path = os.path.join("Server", filename)
    with open(file_path, 'wb') as f:
        while True:
            data = c.recv(1024)
            if not data:
                break
            f.write(data)
    print("Done Receiving")
    c.send(b"File received successfully")

• while False:块永远不会执行，下载逻辑需重新编写：先接收客户端的下载请求，再读取对应文件并发送。

内容的提问来源于stack exchange，提问作者Joshua Scotto Divetta