import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;

public class ChatClient extends Frame {

    TextField tf = new TextField();
    TextArea ta = new TextArea();
    Socket s = null;
    DataOutputStream dos = null;
    DataInputStream dis = null;
    private boolean bool1 = false;

    public static void main(String[] args) {

        new ChatClient().launchFrame();
    }

    public void launchFrame() {

        this.setSize(300, 300);
        this.setLocation(400, 300);
        this.add(ta, BorderLayout.NORTH);
        this.add(tf, BorderLayout.SOUTH);
        pack();
        this.addWindowListener(new WindowAdapter() {

            public void windowClosing(WindowEvent arg0) {
                System.exit(0);
            }
        });// 匿名类，摁右上角关闭窗口功能；
        tf.addActionListener(new TFListener());
        this.setVisible(true);
        connect();// 调用connect();
        new Thread(new Get()).start();
    }

    public void connect() {

        try {
            s = new Socket("127.0.0.1", 8888);
            System.out.println("I am connecting to the server...");
            dos = new DataOutputStream(s.getOutputStream());
            dis = new DataInputStream(s.getInputStream());
            bool1 = true;
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public void disconnect() {
        
        try {
            dos.close();
            dis.close();
            s.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    private class Get implements Runnable {
        
        
        public void run() {
            try {
                while(bool1) {
                String str = dis.readUTF();
                ta.setText(str);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        
    }

    private class TFListener implements ActionListener {

        public void actionPerformed(ActionEvent arg0) {

            String str = tf.getText();
            ta.setText(str);
            tf.setText("");
            
            try {
                dos.writeUTF(str);
                dos.flush();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    
}

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

public class ChatServer {

    List<Client>clients = new ArrayList<Client>();
    
    public static void main(String[] args) {
        
        new ChatServer().started();
    }
    
    public void started() {
        
        boolean started1 = false;
        ServerSocket ss = null;
        Socket s = null;
        
        try {
            ss = new ServerSocket(8888);
        } catch(BindException e) {
            System.out.println("The port has been in used,try another...");
            System.exit(0);
        } catch(Exception e) {
            e.printStackTrace();
        }
        
        try{
            started1 = true;//建立连接后started1变为true；
            while(started1) {
                s = ss.accept();
                Client c = new Client(s);
System.out.println("A client is connecting to me...");
                new Thread(c).start();
                
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                ss.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }
    
    public class Client implements Runnable {
        
        private Socket s;
        private DataInputStream dis;
        private DataOutputStream dos;
        private boolean started2 = false;
        
        Client(Socket s) {
            this.s = s;
            started2 = true;
            try {
                dis = new DataInputStream(s.getInputStream());
                dos = new DataOutputStream(s.getOutputStream());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        
    public void send(String str) {
        try {
            dos.writeUTF(str);
            dos.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void run() {
            
         try {
            while(started2) {
                String str;
                str = dis.readUTF();
System.out.println(str);
                for(int i = 0; i < clients.size(); i++) {
                    Client c = clients.get(i);
                    c.send(str);
                }
                
                /*for(Iterator<Client>it = clients.iterator(); it.hasNext();) {
                    Client c = it.next();
                    c.send(str);
                }*/
                
                /*Iterator<Client>it = clients.iterator();
                while(it.hasNext()) {
                    Client c = it.next();
                    c.send(str);
                }*/
                
                    }
                } catch (IOException e) {
                    System.out.println("A client has been out...");
                } finally {
                    try {
                        if(dis != null) dis.close();
                        if(dos != null) dos.close();
                        if(s != null) s.close();
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
               }
          }
     }
    
    
}