问题
I am trying to send files from a Python server to Java client over a TCP socket. Here is what I have so far:
Java Client (Note that all of the file transfer code is in the getFile() method):
public class Client1
{
private Socket socket = null;
private FileOutputStream fos = null;
private DataInputStream din = null;
private PrintStream pout = null;
private Scanner scan = null;
public Client1(InetAddress address, int port) throws IOException
{
System.out.println("Initializing Client");
socket = new Socket(address, port);
scan = new Scanner(System.in);
din = new DataInputStream(socket.getInputStream());
pout = new PrintStream(socket.getOutputStream());
}
public void send(String msg) throws IOException
{
pout.print(msg);
pout.flush();
}
public void closeConnections() throws IOException
{
// Clean up when a connection is ended
socket.close();
din.close();
pout.close();
scan.close();
}
// Request a specific file from the server
public void getFile(String filename)
{
System.out.println("Requested File: "+filename);
try {
File file = new File(filename);
// Create new file if it does not exist
// Then request the file from server
if(!file.exists()){
file.createNewFile();
System.out.println("Created New File: "+filename);
}
fos = new FileOutputStream(file);
send(filename);
// Get content in bytes and write to a file
int counter;
byte[] buffer = new byte[8192];
while((counter = din.read(buffer, 0, buffer.length)) != -1)
{
fos.write(buffer, 0, counter);
} }
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
And the Python Server:
import socket
host = '127.0.0.1'
port = 5555
# Create a socket with port and host bindings
def setupServer():
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print("Socket created")
try:
s.bind((host, port))
except socket.error as msg:
print(msg)
return s
# Establish connection with a client
def setupConnection():
s.listen(1) # Allows one connection at a time
print("Waiting for client")
conn, addr = s.accept()
return conn
# Send file over the network
def sendFile(filename, s):
f = open(filename, 'rb')
line = f.read(1024)
print("Beginning File Transfer")
while line:
s.send(line)
line = f.read(1024)
f.close()
print("Transfer Complete")
# Loop that sends & receives data
def dataTransfer(conn, s, mode):
while True:
# Send a File over the network
filename = conn.recv(1024)
filename = filename.decode(encoding='utf-8')
filename.strip()
print("Requested File: ", filename)
sendFile(filename, s)
break
conn.close()
s = setupServer()
while True:
try:
conn = setupConnection()
dataTransfer(conn, s, "FILE")
except:
break
I was able to successfully create a messaging program between the server and the client where they passed strings to one another. However, I have been unable to transfer files over the network.
It seems that the Python server is sending over the bytes properly, so the Java side seems to be the problem. Particularly the while loop: while((counter = din.read(buffer, 0, buffer.length)) != -1) has been giving an output of -1 so the writing of the file never actually takes place.
Thanks in advance for the help!
回答1:
For others reference, this is how I got it working in the end.
Server:
import socket
import select
server_addr = '127.0.0.1', 5555
# Create a socket with port and host bindings
def setupServer():
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print("Socket created")
try:
s.bind(server_addr)
except socket.error as msg:
print(msg)
return s
# Establish connection with a client
def setupConnection(s):
s.listen(5) # Allows five connections at a time
print("Waiting for client")
conn, addr = s.accept()
return conn
# Get input from user
def GET():
reply = input("Reply: ")
return reply
def sendFile(filename, conn):
f = open(filename, 'rb')
line = f.read(1024)
print("Beginning File Transfer")
while line:
conn.send(line)
line = f.read(1024)
f.close()
print("Transfer Complete")
# Loop that sends & receives data
def dataTransfer(conn, s, mode):
while True:
# Send a File over the network
if mode == "SEND":
filename = conn.recv(1024)
filename = filename.decode(encoding='utf-8')
filename.strip()
print("Requested File: ", filename)
sendFile(filename, conn)
# conn.send(bytes("DONE", 'utf-8'))
break
# Chat between client and server
elif mode == "CHAT":
# Receive Data
print("Connected with: ", conn)
data = conn.recv(1024)
data = data.decode(encoding='utf-8')
data.strip()
print("Client: " + data)
command = str(data)
if command == "QUIT":
print("Server disconnecting")
s.close()
break
# Send reply
reply = GET()
conn.send(bytes(reply, 'utf-8'))
conn.close()
sock = setupServer()
while True:
try:
connection = setupConnection(sock)
dataTransfer(connection, sock, "CHAT")
except:
break
Client:
import java.net.*;
import java.io.*;
import java.util.Scanner;
public class ClientConnect {
private Socket socket = null;
private FileOutputStream fos = null;
private DataInputStream din = null;
private PrintStream pout = null;
private Scanner scan = null;
public ClientConnect(InetAddress address, int port) throws IOException
{
System.out.println("Initializing Client");
socket = new Socket(address, port);
scan = new Scanner(System.in);
din = new DataInputStream(socket.getInputStream());
pout = new PrintStream(socket.getOutputStream());
}
public void send(String msg) throws IOException
{
pout.print(msg);
pout.flush();
}
public String recv() throws IOException
{
byte[] bytes = new byte[1024];
din.read(bytes);
String reply = new String(bytes, "UTF-8");
System.out.println("Inside recv(): ");
return reply;
}
public void closeConnections() throws IOException
{
// Clean up when a connection is ended
socket.close();
din.close();
pout.close();
scan.close();
}
public void chat() throws IOException
{
String response = "s";
System.out.println("Initiating Chat Sequence");
while(!response.equals("QUIT")){
System.out.print("Client: ");
String message = scan.nextLine();
send(message);
if(message.equals("QUIT"))
break;
response = recv();
System.out.println("Server: " + response);
}
closeConnections();
}
// Request a specific file from the server
public void getFile(String filename)
{
System.out.println("Requested File: "+filename);
try {
File file = new File(filename);
// Create new file if it does not exist
// Then request the file from server
if(!file.exists()){
file.createNewFile();
System.out.println("Created New File: "+filename);
}
fos = new FileOutputStream(file);
send(filename);
// Get content in bytes and write to a file
byte[] buffer = new byte[8192];
for(int counter=0; (counter = din.read(buffer, 0, buffer.length)) >= 0;)
{
fos.write(buffer, 0, counter);
}
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
来源：https://stackoverflow.com/questions/48160009/send-file-from-python-server-to-java-client