JavaFX服务器套接字-发送字符串消息

Question

Im doing the server/client messaging via server socket with javafx.

I have been doing this for a long time now and thought it would be simple enough but I cannot figure this out. I have tried a bunch of different ways but I am just not good enough. Please help me figure it out if you can.

Here is the code for client

    // IO streams
        DataOutputStream toServer = null;
        DataInputStream fromServer = null;
        String serverMessage = "";

  @Override // Override the start method in the Application class
  public void start(Stage primaryStage) {
    // Panel p to hold the label and text field
    BorderPane paneForTextField = new BorderPane();
    Button btnSend = new Button("|>");
    paneForTextField.setPadding(new Insets(5, 5, 5, 5)); 
    paneForTextField.setStyle("-fx-border-color: green");
    paneForTextField.setRight( btnSend );

    TextField tf = new TextField();
    tf.setAlignment(Pos.BOTTOM_RIGHT);
    paneForTextField.setCenter(tf);

BorderPane mainPane = new BorderPane();
// Text area to display contents
TextArea ta = new TextArea();
mainPane.setTop(new ScrollPane(ta));
mainPane.setCenter(paneForTextField);

// Create a scene and place it in the stage
Scene scene = new Scene(mainPane, 450, 270);
primaryStage.setTitle("Client"); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
primaryStage.show(); // Display the stage

tf.setOnAction(e -> {
  try {
    // Get the message from the text field
    String message = tf.getText().trim();

    // Send the message to the server
    toServer.writeBytes(message);
    toServer.flush();
    System.out.println("message sent");
    tf.setText("");

    // Display to the text area
    ta.appendText("client: " + message + "\n");


  }
  catch (IOException ex) {
    System.err.println(ex);
  }
});

try {
  // Create a socket to connect to the server
  Socket socket = new Socket("localhost", 8000);
  // Socket socket = new Socket("130.254.204.36", 8000);
  // Socket socket = new Socket("drake.Armstrong.edu", 8000);

  // Create an input stream to receive data from the server
  fromServer = new DataInputStream( socket.getInputStream() );

  // Create an output stream to send data to the server
  toServer = new DataOutputStream( socket.getOutputStream() );


  new Thread(() -> {
    try{
        while(true){
            serverMessage = fromServer.readUTF();

            System.out.println("message received");

            Platform.runLater( () -> {

                tf.appendText(serverMessage);

            });


        }
    }
    catch(IOException e){
        ta.appendText(e.toString() + "\n");
    }

  }).start();
}
catch (IOException ex) {
  ta.appendText(ex.toString() + '\n');
}
  }

and here is the code for server

private TextField tf = new TextField();
    private ServerSocket serverSocket;
    private Socket socket;
    private DataInputStream input ;
    private BufferedWriter output;
    // Text area for displaying contents
    TextArea ta = new TextArea();

    @Override // Override the start method in the Application class
    public void start(Stage primaryStage) {


         // Create a server socket
        BorderPane borderPaneForText = new BorderPane();
        Button btnSend = new Button("|>");
        btnSend.setOnAction( e-> {

            Platform.runLater( () -> {
                try{

                    output.write(tf.getText());
                    showMessage("server: " + tf.getText() + "\n");

                }
                catch(IOException ex){
                    ex.printStackTrace();
                }
            });
        });

        tf.setAlignment(Pos.BOTTOM_RIGHT);

        borderPaneForText.setCenter(tf);
        borderPaneForText.setRight(btnSend);
        borderPaneForText.setPadding( new Insets( 5, 5, 5, 5) );

        BorderPane mainPane = new BorderPane();
        mainPane.setTop(new ScrollPane(ta));
        mainPane.setCenter(borderPaneForText);

        // Create a scene and place it in the stage
        Scene scene = new Scene(mainPane, 450, 270);
        primaryStage.setTitle("Server"); // Set the stage title
        primaryStage.setScene(scene); // Place the scene in the stage
        primaryStage.show(); // Display the stage

        ta.setEditable(false);
        new Thread( () -> {
            try {
              // Create a server socket
              serverSocket = new ServerSocket(8000);
              Platform.runLater(() ->
                ta.appendText("Server started at " + new Date() + '\n'));

              // Listen for a connection request
              Socket socket = serverSocket.accept();

              // Create data input and output streams
              input = new DataInputStream( socket.getInputStream() );
              output = new BufferedWriter( new OutputStreamWriter(socket.getOutputStream() ) );

              while (true) {
                // Receive message from the client
                String message = input.readUTF();

                output.write(message);

                Platform.runLater(() -> {
                  ta.appendText("Client: " + message + "\n"); 
                });
              }
            }
            catch(IOException ex) {
              ex.printStackTrace();
            }
        }).start();
    }

        /**
         * The main method is only needed for the IDE with limited
         * JavaFX support. Not needed for running from the command line.
         */
        public static void main(String[] args) {
          launch(args);
        }




  public void showMessage(String message){

      Platform.runLater( () -> {
              ta.appendText(message);

      });
  }

I dont know if it is the problem with the datainputstream because It does not have a readline or readString method. A similar program with double worked when I tried it out.

I am trying to make like a basic chatting window on both applications so that both can exchange messages. when I press send in either of the applications, I expect the string to be sent to the other application. Then I want to display that text in the text area in both the server and client, like how real chat behaves. Currently, the strings are shown in their own respective text areas but not the other application.

Answer 1

At Server, you should use private DataOutputStream output; and output.writeUTF(message); and of course output = new DataOutputStream(socket.getOutputStream());

(and not private BufferedWriter output; )

all Server:

public class Main extends Application {

    private TextField tf = new TextField();
    private ServerSocket serverSocket;
    private Socket socket;
    private DataInputStream input ;
    private DataOutputStream output;
    // Text area for displaying contents
    TextArea ta = new TextArea();

    @Override // Override the start method in the Application class
    public void start(Stage primaryStage) {


        // Create a server socket
        BorderPane borderPaneForText = new BorderPane();
        Button btnSend = new Button("|>");
        btnSend.setOnAction( e-> {

            Platform.runLater( () -> {
                try{

                    output.writeUTF(tf.getText());
                    showMessage("server: " + tf.getText() + "\n");

                }
                catch(IOException ex){
                    ex.printStackTrace();
                }
            });
        });

        tf.setAlignment(Pos.BOTTOM_RIGHT);

        borderPaneForText.setCenter(tf);
        borderPaneForText.setRight(btnSend);
        borderPaneForText.setPadding( new Insets( 5, 5, 5, 5) );

        BorderPane mainPane = new BorderPane();
        mainPane.setTop(new ScrollPane(ta));
        mainPane.setCenter(borderPaneForText);

        // Create a scene and place it in the stage
        Scene scene = new Scene(mainPane, 450, 270);
        primaryStage.setTitle("Server"); // Set the stage title
        primaryStage.setScene(scene); // Place the scene in the stage
        primaryStage.show(); // Display the stage

        ta.setEditable(false);
        new Thread( () -> {
            try {
                // Create a server socket
                serverSocket = new ServerSocket(8000);
                Platform.runLater(() ->
                        ta.appendText("Server started at " + new Date() + '\n'));

                // Listen for a connection request
                Socket socket = serverSocket.accept();

                // Create data input and output streams
                input = new DataInputStream( socket.getInputStream() );
                output = new DataOutputStream(socket.getOutputStream());

                while (true) {
                    // Receive message from the client
                    String message = input.readUTF();

                    output.writeUTF(message);
                    Platform.runLater(() -> {
                        ta.appendText("Client: " + message + "\n");
                    });
                }
            }
            catch(IOException ex) {
                ex.printStackTrace();
            }
        }).start();
    }

    /**
     * The main method is only needed for the IDE with limited
     * JavaFX support. Not needed for running from the command line.
     */
    public static void main(String[] args) {
        launch(args);
    }




    public void showMessage(String message){

        Platform.runLater( () -> {
            ta.appendText(message);

        });
    }



}