如何在客户端之间持续发送消息？

Question

我有一个简单的客户端/服务器应用程序，它将 2 个客户端分组并让它们相互通信，如果第三个客户端连接，它将无法与其他 2 个客户端通信，但它会创建另一组 2 个客户端和依此类推...但是，当我从客户端发送消息时，会出现问题，它不会立即将其发送到另一个客户端，而是等待第一个客户端输入，并且还等待第二个客户端输入，并且仅当两者都客户输入了一个输入，它将它们发送给彼此。任何帮助都非常感谢。

服务器：

public class ChatServer {

    Socket previousSocket = null;
    
    public static void main(String[] args) throws Exception {
        ServerSocket serverSocket = new ServerSocket(9001);
        System.out.println("The chat server is running.");
        Socket previousSocket = null;
        while (true) {
            Socket newSocket = serverSocket.accept();
            
            /**
             * if (previousSocket == null) occurs if only 1 client is connected and its being set as a previousSocket
             * and we wait for a second client to connect so meanwhile nothing happens
             * 
             * if second clients joins in we can start communicating in groups of 2
             */
            
            if (previousSocket == null) { 
                previousSocket = newSocket;
            } else {
                new Handler(previousSocket, newSocket).start();
                new Handler(newSocket, previousSocket).start();
                previousSocket = null;
            }
        }
    }

    
    private static class Handler extends Thread {
        private String name;
        private Socket socket;
        private Socket peerSocket;
        private DataInputStream in;
        private DataOutputStream out;

        public Handler(Socket socket, Socket peerSocket) {
            this.socket = socket;
            this.peerSocket = peerSocket;
        }

        public void run() {
            try {
                while (true) {
                in = new DataInputStream(socket.getInputStream());
                out = new DataOutputStream(peerSocket.getOutputStream());
                
                
                

                    try {
                        String input = in.readUTF();
                        

                            out.writeUTF(input);
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                   
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            
        }
    }
}

客户：

public class ChatClient {

    public static void main(String[] args) throws UnknownHostException, IOException {
        new ChatClient();
    }
    
    public ChatClient() throws UnknownHostException, IOException  {
        Socket socket = new Socket("127.0.0.1", 9001);
        
        System.out.println("You can start typing:");
        
        while(true) {
            
            
            Scanner scanner = new Scanner(System.in);
            
            Thread input = new Thread() {
                @Override
                public void run() {
                    while(true) {
                        try {
                            DataInputStream inputStream = new DataInputStream(socket.getInputStream());
                            
                            while(scanner.hasNextLine()) {
                                String message = scanner.nextLine();
                                
                                System.out.println(message);
                                
                                //reading messages from server
                                String received = inputStream.readUTF();
                                System.out.println(received);
                            }
                        } catch (IOException e) {
                            
                            e.printStackTrace();
                        }
                    }
                }
            };
            input.start();
            
            Thread output = new Thread() {
                public void run() {
                    try {
                        DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());
                        while(scanner.hasNextLine()) {
                            String message = scanner.nextLine();
                            
                            if(message.equalsIgnoreCase("quit")) {
                                socket.close();
                                break;
                            }
                            
                            outputStream.writeUTF(message);
                        }
                    } catch (IOException e) {
                        
                        e.printStackTrace();
                    }
                    
                    
                };
            };
            output.start();

            
        }
    }
}

Answer 1

在客户端读取服务器时删除顶级while循环并删除scanner.nextLine()。
我已经在下面更新了您的客户端代码，这应该可以正常工作。

public class ChatClient {

    public static void main(String[] args) throws UnknownHostException, IOException {
        new ChatClient();
    }
    
    public ChatClient() throws UnknownHostException, IOException  {
        Socket socket = new Socket("127.0.0.1", 9001);
        
        System.out.println("You can start typing:");
            
            
            Scanner scanner = new Scanner(System.in);
            System.out.println("got it");
            Thread input = new Thread() {
                @Override
                public void run() {
                    while(true) {
                        try {
                            DataInputStream inputStream = new DataInputStream(socket.getInputStream());
                            
                            while(true) {
                                //String message = scanner.nextLine();
                                
                                //System.out.println(message);
                                
                                //reading messages from server
                                String received = inputStream.readUTF();
                                System.out.println(received);
                            }
                        } catch (IOException e) {
                            
                            e.printStackTrace();
                        }
                    }
                }
            };
            input.start();
            
            Thread output = new Thread() {
                public void run() {
                    try {
                        DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());
                        while(scanner.hasNextLine()) {
                            String message = scanner.nextLine();
                            
                            if(message.equalsIgnoreCase("quit")) {
                                socket.close();
                                break;
                            }
                            
                            outputStream.writeUTF(message);
                        }
                    } catch (IOException e) {
                        
                        e.printStackTrace();
                    }
                    
                    
                };
            };
            output.start();
    }
}

Answer 2

您需要将客户端中的输入和输出流分成两个单独的线程。问题是您的客户端在您读取输入之前正在等待扫描仪的输入。 Scanner 是一个阻塞调用，所以它需要自己的线程。

此外，您应该将循环中数据流的创建移至构造函数...这将提高您的效率。