从客户端套接字向服务器套接字发送消息时出现问题

Question

I'm new to socket. I want to make a client-server program but I have a problem when it comes to printing messages on the side of the server. That leads me to believe there is a problem in my Client class when it is sending the messages. The first message that is sent from client to server is delivered fine but the rest aren't printed even though the sequence number is printed.

Here are both classes:

Client class:

public class Cliente extends Conexion {
    private String mensaje;
    private String recibeTeclado;
    int numSec = 0;
    String tipo = "0";
    private int num;
    int c;
    
    public Cliente() throws IOException{
        super("cliente");
    } 
    
    public void startClient() {
        try {
            salidaServidor = new DataOutputStream(cs.getOutputStream());
            
            Scanner lee = new Scanner(System.in);
            System.out.println("How many messages do you want to send?");
            num = lee.nextInt();
            salidaServidor.writeUTF(":" + num + "\n"); 
            for (int i = 1; i <= num; i++) {
                numSec++;
                System.out.println("Enter the message: ");
                recibeTeclado = lee.next();
                mensaje = tipo + ":" + Integer.toString(numSec) + ":" + recibeTeclado + "\n";
                salidaServidor.writeUTF(mensaje);
                salidaServidor.flush();
                BufferedReader in = new BufferedReader (new InputStreamReader (cs.getInputStream()));
                String mensajeDelServidor = in.readLine();
                System.out.println("Status : " + mensajeDelServidor);  
            } 
            cs.close();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

Server class:

public class Servidor extends Conexion{
    String nuevo;
    int numSec=0;
    String tipo="1";
    int num;
    String [] n;
    public Servidor() throws IOException{super("servidor");}
    public void startServer() {
        try {
            System.out.println("Waiting..."); 
            cs = ss.accept();
            BufferedReader numString = new BufferedReader(new InputStreamReader(cs.getInputStream()));
            n=numString.readLine().split(":");
            num=Integer.parseInt(n[1]);
            for(int i=1; i<=num; i++) {

                salidaCliente=new DataOutputStream(cs.getOutputStream());
                numSec++;
                System.out.println(numSec);
                nuevo= tipo +":"+ Integer.toString(numSec) +":"+ "Received\n";
                salidaCliente.writeUTF(nuevo);
                salidaCliente.flush();
                BufferedReader entrada = new BufferedReader(new InputStreamReader(cs.getInputStream()));
                boolean band=false;
                while((mensajeServidor=entrada.readLine())!=null && !band) {
                    String[] arrSplit = mensajeServidor.split(":");
                    System.out.println(arrSplit[2]);
                    band=true;
                }
            }

            System.out.println("Fin de la conexión");

            ss.close();
            cs.close();
        }catch (Exception e)
        {
            System.out.println(e.getMessage());
        }
    }
}

Answer 1

[Updated, thanks to @user207421's comment]

2 solutions

1. Keep using DataOutputStream.writeUTF
   Then you have to use DataInputStream.readUTF instead of BufferedReader.readLine .
   And if you want to use '\n' as a separator, you will have to detect such characters

2. Keep using BufferedReader.readLine
   Then you have to use an output stream method like Writer.write instead of DataOutputStream.writeUTF .
   Use only one BufferedReader instance, on server side at least ( numString will keep buffered data that will not be available for the entrada instance).
   For UTF-8, use:

BufferedReader in = new BufferedReader(new InputStreamReader(cs.getInputStream(), "UTF-8"));
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(cs.getOutputStream(), "UTF-8"));

Answer 2

On the client side, you should use a PrintWriter instead of a DataOutputStream to write data to the server:

salidaServidor = new PrintWriter(cs.getOutputStream(), true);

On the server side, 'salidaCliente' should also be a PrintWriter.