用于数据报类型套接字的ServerSocket吗？

Question

I have a ftp client-server program which currently uses TCP. I need to now make it work using UDP, so using datagram sockets instead.

They way it was working was to create a ServerSocket which would listen for a connection, then give that connection to a Socket , and start a separate thread for that socket.

But now using DatagramSocket , there's no equivalent DatagramServerSocket, so I've no idea how I can give clients separate sockets anymore. Is there a server socket for datagrams?

import java.io.IOException;
import java.net.*;

public class Server {

    public static void main(String[] args) throws IOException {

        Socket sock;
        ServerSocket servSock = new ServerSocket(4444, 600);

        while(true){
            sock = servSock.accept();
            new ClientHandler(sock).start();
        }
    }
}

Answer 1

Well, UDP is a connectionless protocol. Doing decent file transfer would probably mean implementing a decent chunk of TCP-like functionality.

Answer 2

DatagramSocket serverSocket  = new DatagramSocket(PORT_NUMBER);`

Will act as a server socket.

alternatively you could use

DatagramChannel channel = DatagramChannel.open();
channel.socket().bind(new InetSocketAddress(9999));

Answer 3

You don't need to give clients separate sockets. You have the source address in each datagram. That tells you which client the datagram is from. You only need one socket in a UDP server.