Java ServerSocket /套接字聊天程序

Question

i tried to make a little chat program, but it really don't want to work. My server and client are mostly the same: they create a new socket and a new Chat (GUI). Can someone help me find the mistake i made?

Server Code:

import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;

import java.net.Socket;
import java.net.ServerSocket;

public class Server {
    private     Chat            ch      = null;
    private     ServerSocket    server  = null;
    private     Socket          s       = null;
    private     BufferedReader  in      = null;
    private     BufferedWriter  out     = null;

    public Server() {
        try {
            server = new ServerSocket(1792);
            s = server.accept();
            in = new BufferedReader(new InputStreamReader(s.getInputStream()));
            out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            ch = new Chat("Server", out);
        } catch (IOException ioe) {

        }

        new Thread(new Runnable() {
            public void run() {
                while (true) {
                    try {
                        String line = in.readLine();
                        ch.showString(line);
                    } catch (IOException e) {
                        System.exit(0);     // exit program when connection is lost
                        return;
                    }
                }
            }
        }).start();
    }
}

Client Code:

import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;

import java.net.Socket;

public class Client {
    private     Chat            ch      = null;
    private     Socket          s       = null;
    private     BufferedReader  in      = null;
    private     BufferedWriter  out     = null;

    public Client() {
        try {
            s = new Socket("localHost", 1792);
            in = new BufferedReader(new InputStreamReader(s.getInputStream()));
            out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            ch = new Chat("Client", out);
        } catch (IOException ioe) {

       }

        new Thread(new Runnable() {
            public void run() {
                while (true) {
                    try {
                        String line = in.readLine();
                        ch.showString(line);
                    } catch (IOException e) {
                        System.exit(0);     // exit program when connection is lost
                        return;
                    }
                }
            }
        }).start();
    }
}

Chat (GUI) Code:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Insets;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JLabel;

import java.io.BufferedWriter;
import java.io.IOException;

public class Chat implements ActionListener {
    protected   JFrame          fr;
    private     JPanel          p;
    private     JTextField      tf;
    private     JButton         b;
    private     int             lines   = 20;
    private     JLabel[]        l       = new JLabel[lines];
    private     String          title   = "";
    private     BufferedWriter  out;

    public Chat(String name, BufferedWriter bw) {
        title = name;
        out = bw;

        fr = new JFrame(title);
        fr.setLayout(new BorderLayout());
        fr.setDefaultCloseOperation(fr.EXIT_ON_CLOSE);
        fr.setSize(400, 475);
        fr.setLocationRelativeTo(null);
        fr.setResizable(false);
        fr.setVisible(true);

        Insets in = fr.getInsets();
        int width = fr.getWidth() - in.left - in.right;
        int height = fr.getHeight() - in.top - in.bottom;

        p = new JPanel();
        p.setLayout(null);
        p.setBackground(Color.WHITE);
        fr.add(p, BorderLayout.CENTER);

        tf = new JTextField();
        tf.setHorizontalAlignment(tf.LEFT);
        tf.addActionListener(this);
        tf.setBounds(0, 400, 300, height-400);
        p.add(tf);

        b = new JButton("Send");
        b.setBounds(300, 400, width-300, height-400);
        b.addActionListener(this);
        p.add(b);

        p.validate();
        fr.validate();

        p.repaint();
        fr.repaint();

        for(int i=0;i<lines;i++) {
            l[i] = new JLabel("");
            l[i].setHorizontalAlignment(l[i].LEFT);
            l[i].setBounds(0, 400*i/lines, 500, 400/lines);
            p.add(l[i]);
        }
    }

    public void showString(String text) {
        if (text.equals("")) return;
        for(int i=0;i<lines-1;i++) {
            l[i].setText(l[i+1].getText());
        }
        l[lines-1].setText(text);
    }

    public void actionPerformed(ActionEvent ae) {
        String text = tf.getText();
        try {
            showString(text);
            out.write(text);
            out.flush();
            tf.setText("");
        } catch (IOException ioe) {

        }
    }
}

Answer 1

The readLine() function waits for the end of line. In your chat class, you are never giving it an end of line while writing to the output stream. And so both server and client waits up at in.readLine() for an end of line character so as to complete reading a single line. You need to give it an end of line character after each line you write to the output stream. Only flushing it will not suffice.

So simply modify this part in your Chat class.

Old code

        out.write(text);
        out.flush();

New code

        out.write(text);
        out.write('\n');
        out.flush();

Rest all of the code is working absolutely fine. Good luck!