如何使服务器在同一端口上接受多个套接字

Question

I want the ServerSocket to accept 2 Sockets connecting on the same port. However, it will not print out what is being read from the BufferedReader and the sockets after being connected are still null.

Here is the Serversocket code:

ServerSocket serverSocket = new ServerSocket(PORT);
try {
Socket con;
int socketCounter= 0;
Socket first, second;
while (socketCounter!= 2) {
        con = serverSocket.accept();
        String input;
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        if ((input = in.readLine()) != null) {
            System.out.println(input);
            if (input.equals("first")) {
                first = con;
            } else if (input.equals("second")) {
                second = con;
            } else {
                continue;
            }
        }
        socketCounter++;
    }
} catch (Exception e) {
    e.printStackTrace();
}

Here is the "first"

try {
    first = new Socket(URL, PORT);
ObjectOutputStream out = new ObjectOutputStream(first.getOutputStream());
ObjectInputStream in = new ObjectInputStream(first.getInputStream());
PrintWriter pw = new PrintWriter(new OutputStreamWriter(first.getOutputStream()));
pw.println("first");
pw.flush();
} catch(Excpetion e){
    e.printStackTrace();
}

Second is basically the same:

try {
    second = new Socket(URL, PORT);
ObjectOutputStream out = new ObjectOutputStream(second.getOutputStream());
ObjectInputStream in = new ObjectInputStream(second.getInputStream());
PrintWriter pw = new PrintWriter(new OutputStreamWriter(second.getOutputStream()));
pw.println("second");
pw.flush();
} catch(Excpetion e){
    e.printStackTrace();
}

I would preferably want to do this single threaded, however, if not, it's fine. Can anyone help?

Answer 1

When you create a ServerSocket, you have to define the port that server socket it will use to listen the client requests. Everytime that ServerSocket receives a request, that request will be redirect to another port defined by the ServerSocket. Normally, we instanciate a new thread and associate to it the a client work. Check this example: http://www.oracle.com/technetwork/java/socket-140484.html