服务器端代码

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Server extends JFrame implements ActionListener
{
    private Socket s;
    private ServerSocket ss;
    private BufferedReader br;
    private BufferedWriter    bw;
    
    private JTextField tf = new JTextField();
    private JTextArea ta = new JTextArea();
    private JScrollPane sp = new JScrollPane(ta,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    
    public Server()
    {
        try 
        {
            this.getContentPane().add(tf,"North");
            this.getContentPane().add(sp,"Center");
            
            tf.addActionListener(this);
            this.setTitle("服务器");
            this.setSize(400,400);
            this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            this.setResizable(false);
            this.setVisible(true);
            
            ss = new ServerSocket(9000);
            s = ss.accept();
            br = new BufferedReader(new InputStreamReader(s.getInputStream()));
            bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            
            new ServerReader().start();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
    
    class ServerReader extends Thread
    {
        public void run()
        {
            try 
            {
                while(true)
                {
                    String str = null;
                    if((str=br.readLine())!=null)
                        ta.append(str+"\r\n");
                }
            }
            catch (Exception e) 
            {
                
            }
        }
    }
    
    public static void main(String[] args) 
    {
        new Server();
    }

    public void actionPerformed(ActionEvent e) 
    {
        try 
        {
            bw.write(tf.getText()+"\r\n");
            bw.flush();
            tf.setText("");
        } 
        catch (Exception ex) 
        {
            
        }        
    }
}

客户端代码
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;


public class Client extends JFrame implements ActionListener
{
    private Socket s;
    private BufferedReader br;
    private BufferedWriter bw;
    
    private JTextField tf = new JTextField();
    private JTextArea ta = new JTextArea();
    private JScrollPane sp = new JScrollPane(ta,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    
    public Client()
    {
        try 
        {
            
            this.getContentPane().add(tf,"North");
            this.getContentPane().add(sp,"Center");
            
            tf.addActionListener(this);
            
            this.setTitle("客户端");
            this.setSize(400,400);
            this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            this.setResizable(false);
            this.setVisible(true);
            
            s = new Socket("127.0.0.1",9000);
            br = new BufferedReader(new InputStreamReader(s.getInputStream()));
            bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            
            new ClientReader().start();
        }
        catch (Exception e) 
        {
            e.printStackTrace();
        }
    }
    
    
    class ClientReader extends Thread
    {
        public void run()
        {
            try 
            {
                while(true)
                {
                    String str = null;
                    if((str=br.readLine())!=null)
                        ta.append(str+"\r\n");
                }
            }
            catch (Exception e) 
            {
            
            }
        }
    }
    
    
    public static void main(String[] args) 
    {
        new Client();
    }

    public void actionPerformed(ActionEvent e) 
    {
        try 
        {
            bw.write(tf.getText()+"\r\n");
            bw.flush();
            tf.setText("");
        }
        catch (Exception ex) 
        {
            
        }
    }
}