服务器通过Java中的套接字对选定客户端的响应

Question

I'm gonna create simple chat between 2 Android devices, in Java. I found simple script for server, but i'm new in programming sockets.

Problem: I want receive message from client A and send to client B.

I know how to create "echo" response to the same client, but how to send message to the other client?

Now serwer look like this:

              {
             String clientSentence;
             String capitalizedSentence;
             ServerSocket welcomeSocket = new ServerSocket(19198);
             Socket connectionSocket = welcomeSocket.accept();
             while(true)
             {

                BufferedReader inFromClient =
                   new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
                DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
                clientSentence = inFromClient.readLine();
                System.out.println("Received: " + clientSentence);
                capitalizedSentence = clientSentence.toUpperCase() + '\n';
                outToClient.writeBytes(capitalizedSentence);
             }


          }

Answer 1

You need to keep track of your clients and their sockets/streams, and then you know where to send the message. You also need to start a new thread for each client.

You can find many examples if you google for Java chat server...