在 Python 中通过 TCP 套接字发送文件
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Sending a file over TCP sockets in Python
提问by Swaathi Kakarla
I've successfully been able to copy the file contents (image) to a new file. However when I try the same thing over TCP sockets I'm facing issues. The server loop is not exiting. The client loop exits when it reaches the EOF, however the server is unable to recognize EOF.
我已经成功地将文件内容（图像）复制到一个新文件中。然而，当我通过 TCP 套接字尝试同样的事情时，我遇到了问题。服务器循环没有退出。客户端循环在到达 EOF 时退出，但是服务器无法识别 EOF。
Here's the code:
这是代码：
Server
服务器
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
f = open('torecv.png','wb')
s.listen(5) # Now wait for client connection.
while True:
c, addr = s.accept() # Establish connection with client.
print 'Got connection from', addr
print "Receiving..."
l = c.recv(1024)
while (l):
print "Receiving..."
f.write(l)
l = c.recv(1024)
f.close()
print "Done Receiving"
c.send('Thank you for connecting')
c.close() # Close the connection
Client
客户
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.connect((host, port))
s.send("Hello server!")
f = open('tosend.png','rb')
print 'Sending...'
l = f.read(1024)
while (l):
print 'Sending...'
s.send(l)
l = f.read(1024)
f.close()
print "Done Sending"
print s.recv(1024)
s.close # Close the socket when done
Here's the screenshot:
这是屏幕截图：
Server
服务器
Client
客户
Edit 1: Extra data copied over. Making the file "not complete." The first column shows the image that has been received. It seems to be larger than the one sent. Because of this, I'm not able to open the image. It seems like a corrupted file.
编辑 1：复制的额外数据。使文件“不完整”。第一列显示已接收的图像。它似乎比发送的更大。因此，我无法打开图像。它看起来像一个损坏的文件。
Edit 2: This is how I do it in the console. The file sizes are the same here.
编辑 2：这就是我在控制台中的做法。此处的文件大小相同。
采纳答案by falsetru
Client need to notify that it finished sending, using socket.shutdown(not socket.closewhich close both reading/writing part of the socket):
客户端需要通知它已完成发送，使用socket.shutdown（不是socket.close关闭套接字的读/写部分）：
...
print "Done Sending"
s.shutdown(socket.SHUT_WR)
print s.recv(1024)
s.close()
UPDATE
更新
Client sends Hello server!to the server; which is written to the file in the server side.
客户端发送Hello server!到服务器；写入服务器端的文件中。
s.send("Hello server!")
Remove above line to avoid it.
删除上面的行以避免它。
回答by gajendra
The problem is extra 13 byte which server.py receives at the start. To resolve that write "l = c.recv(1024)" twice before the while loop as below.
问题是 server.py 在开始时收到的额外 13 字节。要解决该问题，请在 while 循环之前写入两次“l = c.recv(1024)”，如下所示。
print "Receiving..."
l = c.recv(1024) #this receives 13 bytes which is corrupting the data
l = c.recv(1024) # Now actual data starts receiving
while (l):
This resolves the issue, tried with different format and sizes of files. If anyone knows what this starting 13 bytes refers to, please reply.
这解决了问题，尝试使用不同的文件格式和大小。如果有人知道这个起始 13 个字节是什么意思，请回复。
回答by Rama Krishna
Remove below code
删除下面的代码
s.send("Hello server!")
because your sending s.send("Hello server!")to server, so your output file is somewhat more in size.
因为您发送s.send("Hello server!")到服务器，所以您的输出文件的大小要大一些。
回答by Irviano Yoe
Put file inside while Truelike so
while True像这样把文件放在里面
while True:
f = open('torecv.png','wb')
c, addr = s.accept() # Establish connection with client.
print 'Got connection from', addr
print "Receiving..."
l = c.recv(1024)
while (l):
print "Receiving..."
f.write(l)
l = c.recv(1024)
f.close()
print "Done Receiving"
c.send('Thank you for connecting')
c.close()
回答by DAkbariSE
you may change your loop condition according to following code, when length of l is smaller than buffer size it means that it reached end of file
您可以根据以下代码更改循环条件，当 l 的长度小于缓冲区大小时，表示它已到达文件末尾
while (True):
print "Receiving..."
l = c.recv(1024)
f.write(l)
if len(l) < 1024:
break
回答by Ahmed
You can send some flag to stop while loop in server
您可以发送一些标志来停止服务器中的循环
for example
例如
Server side:
服务器端：
import socket
s = socket.socket()
s.bind(("localhost", 5000))
s.listen(1)
c,a = s.accept()
filetodown = open("img.png", "wb")
while True:
print("Receiving....")
data = c.recv(1024)
if data == b"DONE":
print("Done Receiving.")
break
filetodown.write(data)
filetodown.close()
c.send("Thank you for connecting.")
c.shutdown(2)
c.close()
s.close()
#Done :)
Client side:
客户端：
import socket
s = socket.socket()
s.connect(("localhost", 5000))
filetosend = open("img.png", "rb")
data = filetosend.read(1024)
while data:
print("Sending...")
s.send(data)
data = filetosend.read(1024)
filetosend.close()
s.send(b"DONE")
print("Done Sending.")
print(s.recv(1024))
s.shutdown(2)
s.close()
#Done :)
