简单的 Python 服务器客户端文件传输

Question

我正在进行这个简单的 python 服务器-客户端文件传输项目。 每边有两个部分。首先，客户端将文件发送到服务器的第一部分。然后服务器附加一行并将文件在第二部分发送回客户端。

我的问题是，由于某种原因，只要我有返回文件代码，服务器代码就会卡在接收状态。如果我应该注释掉代码的第二部分，服务器会收到客户端发送的所有文件。否则它会在接收时冻结。是的，客户确实发送了它。

你可以忽略所有的打印命令，只是在那里看看问题出在哪里。

服务器代码：

import socket

ssFT = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ssFT.bind((socket.gethostname(), 8756))
ssFT.listen(1)
while True:
    (conn, address) = ssFT.accept()
    text_file = 'fileProj.txt'

    #Receive, output and save file
    with open(text_file, "wb") as fw:
        print("Receiving..")
        while True:
            print('receiving')
            data = conn.recv(1024)
            print('Received: ', data.decode('utf-8'))
            if not data:
                print('Breaking from file write')
                break
            fw.write(data)
            print('Wrote to file', data.decode('utf-8'))
        fw.close()
        print("Received..")

    #Append and send file
    print('Opening file ', text_file)
    with open(text_file, 'ab+') as fa:
        print('Opened file')
        print("Appending string to file.")
        string = b"Append this to file."
        fa.write(string)
        fa.seek(0, 0)
        print("Sending file.")
        while True:
            data = fa.read(1024)
            conn.send(data)
            if not data:
                break
        fa.close()
        print("Sent file.")
    break
ssFT.close()

客户端代码：

 import socket

csFT = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
csFT.connect((socket.gethostname(), 8756))

text_file = 'passphrase.txt'

#Send file
with open(text_file, 'rb') as fs: 
    #Using with, no file close is necessary, 
    #with automatically handles file close
    while True:
        data = fs.read(1024)
        print('Sending data', data.decode('utf-8'))
        csFT.send(data)
        print('Sent data', data.decode('utf-8'))
        if not data:
            print('Breaking from sending data')
            break
    fs.close()

#Receive file
print("Receiving..")
with open(text_file, 'wb') as fw:
    while True:
        data = csFT.recv(1024)
        if not data:
            break
        fw.write(data)
    fw.close()
print("Received..")

csFT.close()

Answer 1

我使用 Python 3 在本地测试了您的代码。

我看到的问题是服务器代码中的 conn.recv。因为 conn.recv 阻塞了连接，它正在等待更多数据。

我找到的解决方案是向服务器发送命令，通知数据传输的 BEGIN 和 END，如下所示：

client.py

#Send file
with open(text_file, 'rb') as fs: 
    #Using with, no file close is necessary, 
    #with automatically handles file close
    csFT.send(b'BEGIN')
    while True:
        data = fs.read(1024)
        print('Sending data', data.decode('utf-8'))
        csFT.send(data)
        print('Sent data', data.decode('utf-8'))
        if not data:
            print('Breaking from sending data')
            break
    csFT.send(b'ENDED') # I used the same size of the BEGIN token
    fs.close()

server.py

with open(text_file, "wb") as fw:
    print("Receiving..")
    while True:
        print('receiving')
        data = conn.recv(32)
        if data == b'BEGIN':
            continue
        elif data == b'ENDED':
            print('Breaking from file write')
            break
        else:
            print('Received: ', data.decode('utf-8'))
            fw.write(data)
            print('Wrote to file', data.decode('utf-8'))
    fw.close()
    print("Received..")

Client.py 完整代码： https://pastebin.com/LySsgEe4

Server.py 完整代码： https://pastebin.com/KADZpqkM

希望能帮到你！

Answer 2

我解决这个问题的方法是先发送文件大小，然后服务器可以在收到整个文件后立即停止等待。我不知道是否有更好的解决方案，但这就像一个魅力：

BUFFER_SIZE = 1024

client.py

import os
fsize = os.path.getsize(text_file)
csFT.send(str(fsize).encode('utf-8'))

with open(text_file, 'rb') as fs:
    data = fs.read(BUFFER_SIZE)
    while data:
        csFT.send(data)
        data = fs.read(BUFFER_SIZE)

server.py

with open(text_file, 'wb') as fw:
    msg = ssFT.recv(BUFFER_SIZE)
    fsize = int(msg.decode('utf-8'))
    rsize = 0

    while True:
        data = ssFT.recv(BUFFER_SIZE)
        rsize = rsize + len(data)
        fw.write(data)
        if  rsize >= fsize:
            print('Breaking from file write')
            break