Java IO套接字未发送输出流

Question

When debugging my code, the code stops here:

while (( msg = reader.readLine())  != null) {
        writer.write("From server: " + msg);
}

I am sending input from a client class, but I can't figure out where I am wrong, since the server never receives the message.

Here is my entire sever class:

    import java.io.*;
import java.net.*;


public class Server {

    private BufferedReader reader;
    private PrintWriter writer;
    private int port;

    public Server(int port)
    {
        this.port = port;
    }

    private String getSeverAddress() {      
        String host = null;
        try {
            InetAddress adr = InetAddress.getLocalHost();
            host = adr.getHostAddress();

        } catch (UnknownHostException e) {          
            e.printStackTrace();
        }

        return host;
    }

    public void startServer() {

        print("Contact this sever on address: " + getSeverAddress() + " port: " + port);

        ServerSocket ss = null; 
        Socket socket = null;

        try {
            ss = new ServerSocket(port);
            socket = ss.accept();

            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new PrintWriter(socket.getOutputStream(), true);

            String msg = null;

            while (( msg = reader.readLine())  != null) {
                writer.write("From server: " + msg);
                print(msg);

                if(msg.toLowerCase().equals("Bye")) {
                    print("Client left");
                    break;
                }
            }

            ss.close();
            socket.close();
            reader.close();
            writer.close();

        } catch(SocketException e) {
            e.printStackTrace();            
        } catch (IOException i ) {
            i.printStackTrace();
            return;
        }
    }       

    private void print(String msg) {
        System.out.println(msg);
    }

    public static void main(String[] args) {

        Server server = new Server(1111);
        server.startServer();

    }

}

And here is the client class:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;


public class Client {

    private Socket client;
    private BufferedReader reader;
    private PrintWriter writer;

    public Client(Socket socket)
    {
        client = socket;

        try{
            reader = new BufferedReader(new InputStreamReader(client.getInputStream()));
            writer = new PrintWriter(client.getOutputStream(), true);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void writeToServer() {       
        print("Write message to server");

        String msg = null;

        try {
            while((msg = reader.readLine()) != null) {
                writer.write("From client: " + msg);
                print(msg);

                if(msg.toLowerCase().equals("quit")) {
                    break;
                }
            }

            reader.close();
            writer.close();

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

    }

    private void print(String msg) {
        System.out.println(msg);
    }

    public static void main(String[] args) {
        Socket socket = null;

        try {
            socket = new Socket("localhost", 1111);

        } catch (Exception e) {
            e.printStackTrace();
        } 

        Client client = new Client(socket);
        client.writeToServer();
    }

}

Answer 1

Your mistake is server and client both sending/receiving messages background without printing anything. Like when you send message from client, Server received it and again write to the client and it become infinite loop.

Following things are wrong:

Server.java

 try {
         while (( msg = reader.readLine())  != null) {
            print(msg);
            if(msg.toLowerCase().equals("bye")) {
                print("Client left");
                break;
            }
            writer.write("From server: " + msg);
        }

Should be the last statement of loop writer.write("From client: " + msg); and if(msg.toLowerCase().equals("Bye")) should bye

Client.java

try {
           while((msg = reader.readLine()) != null) {
               print(msg);
                if(msg.toLowerCase().equals("quit")) {
                    break;
                }
              writer.write("From client: " + msg);
            }

It should be last in loop writer.write("From client: " + msg);

Answer 2

You're reading lines but you aren't sending lines. You need to send a line terminator.