服務(wù)器端源代碼(ChatServer.java)如下：
import java.net.*;
import java.io.*;
import java.util.*;
/**
 * <p>Title: Java Applet實(shí)現(xiàn)網(wǎng)絡(luò)聊天室</p>
 * <p>Description: Java Applet是通過(guò)瀏覽器面向用戶(hù)的Java小應(yīng)用程序</p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: cumt</p>
 * @author yanglinsen
 * @version 1.0
 */
public class ChatServer {
/*
* m_threads是一個(gè)Vector靜態(tài)變量,它維護(hù)所有Server方的
* ServerThread實(shí)例，通過(guò)該變量能向所有連入Internet
* 的Applet廣播信息
*/
//Chat Server的主方法入口。
//該方法監(jiān)聽(tīng)Chat Applet的請(qǐng)求，并為新連接的
//Applet創(chuàng)建一個(gè)服務(wù)線(xiàn)程
  public static void main(String args[])
  {
        ServerSocket socket=null;
        Vector m_threads=new Vector();
        System.out.println("服務(wù)器已啟動(dòng)，正在等待客戶(hù)的請(qǐng)求...");
        try
        {
            //設(shè)置Server監(jiān)聽(tīng)端口號(hào)為8000, 這個(gè)數(shù)字必須
            //和程序ChatClient中的port參數(shù)一致。
            socket=new ServerSocket(8000);
        }
        catch(Exception e)
        {
            System.out.println("服務(wù)接口建立失敗!");
            return;
        }
        try
        {
            int nid=0;
            while(true)
            {
                //監(jiān)聽(tīng)是否有新Chat Applet連接到Server,
                //線(xiàn)程運(yùn)行到該語(yǔ)句會(huì)封鎖，直到有新的連接產(chǎn)生。
                Socket s=socket.accept();
                //創(chuàng)建一個(gè)新的ServerThread.
                ServerThread  st=new  ServerThread(s,m_threads);
                //為該線(xiàn)程設(shè)置一個(gè)ID號(hào)。
                st.setID(nid++);
                //將該線(xiàn)程加入到m_threads Vector中。
                m_threads.addElement(st);
                //啟動(dòng)服務(wù)線(xiàn)程。
                new Thread(st). start();
                //通知所有Chat Applet有一個(gè)新的網(wǎng)友加入。
                for(int i=0;i<m_threads.size();i++)
                {
                    ServerThread st1=(ServerThread)m_threads.elementAt(i);
                    st1.write("<服務(wù)器>歡迎 "+st.getID()+"號(hào)朋友進(jìn)入聊天室!");
                }
                System.out.println("接受"+st.getID()+"號(hào)客戶(hù)請(qǐng)求");
                System.out.println("繼續(xù)等待其他客戶(hù)的請(qǐng)求...\n");
            }
        }
        catch(Exception e)
        {
            System.out.println("服務(wù)器已關(guān)閉...");
        }

    }
}
/*
* 監(jiān)聽(tīng)線(xiàn)程，監(jiān)聽(tīng)對(duì)應(yīng)的Chat Applet是否有信息傳來(lái)。
*/
    class ServerThread implements Runnable
    {
        Vector m_threads;
        Socket m_socket=null;
        DataInputStream m_in=null;
        DataOutputStream m_out=null;
        int m_nid;

        //初始化該線(xiàn)程。
        public ServerThread(Socket s,Vector threads)
        {
            m_socket=s;
            m_threads=threads;
            try
            {
                m_in=new DataInputStream(m_socket.getInputStream());
                m_out=new DataOutputStream(m_socket.getOutputStream());
            }
            catch(Exception e)
            {
            }
        }
        public void run()  //線(xiàn)程的執(zhí)行體。
        {
            System.out.println("等待進(jìn)程正在運(yùn)行");
            try
            {
                while(true)
                {
                    //監(jiān)聽(tīng)對(duì)應(yīng)的Applet是否傳來(lái)消息
                    //程序陷入到m_in.readUTF()中，直到有信息傳來(lái)才返回。
                    String s=m_in.readUTF();
                    if (s==null)
                      break;
                    //如果Chat Applet傳來(lái)的信息為"leave",
                    //則通知所有其他的的Chat Applet自己退出了。
                    if  (s.trim().equals ("leave"))
                      for (int i=0;i<m_threads.size();i++)
                        {
                          ServerThread st=(ServerThread)m_threads.elementAt(i);
                          st.write("*各位朋友， "+getID()+"號(hào)朋友離開(kāi)聊天室"+"！*");
                        }
                    else
                    //向所有Chat Applet廣播該信息。
                    for(int i=0;i<m_threads.size();i++)
                    {
                        ServerThread st=(ServerThread)m_threads.elementAt(i);
                        st.write("<"+getID()+"朋友說(shuō)>"+s);
                    }
                }
            }
            catch(Exception e)
            {  e.printStackTrace();
            }
            //從m_threads Vector中刪除該線(xiàn)程，表示該線(xiàn)程已經(jīng)離開(kāi)聊天室。
            m_threads.removeElement(this);
            try
            { m_socket.close();
            }
            catch (Exception e){}
        }
        //將msg送回對(duì)應(yīng)的Applet
        public void write (String msg)
        {
            synchronized(m_out)
            {
                try
                {
                    m_out.writeUTF(msg);
                }
                catch(IOException e){}
            }
        }
        public int getID()  //獲得該線(xiàn)程的ID.
        {
            return m_nid;
        }
        public void setID(int nid)  // //設(shè)置線(xiàn)程的ID.
        {
            m_nid=nid;
        }
}

客戶(hù)端源代碼(ChatClientApplet.java)如下：
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import com.borland.jbcl.layout.*;
import javax.swing.*;
import java.io.*;
import java.net.*;

/**
 * <p>Title: Java Applet實(shí)現(xiàn)網(wǎng)絡(luò)聊天室</p>
 * <p>Description: Java Applet是通過(guò)瀏覽器面向用戶(hù)的Java小應(yīng)用程序</p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: cumt</p>
 * @author yanglinsen
 * @version 1.0
 */

public class ChatClientApplet extends Applet implements Runnable {
  private boolean isStandalone = false;
  JLabel jLabel1 = new JLabel();
  JTextField jTextField1 = new JTextField();
  JLabel jLabel2 = new JLabel();
  JButton jButton1 = new JButton();
  DataInputStream  m_in;   //消息輸入流
  DataOutputStream  m_out; //消息輸出流
  JScrollPane jScrollPane1 = new JScrollPane();
  JTextArea jTextArea1 = new JTextArea();
  JLabel jLabel3 = new JLabel();
  //Get a parameter value
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }

  //Construct the applet
  public ChatClientApplet() {
  }
  //Initialize the applet
  public void init() {
    m_in=null;
    m_out=null;
    try{
      URL  url=getCodeBase();  //獲取applet 的URL 值。
      //獲取服務(wù)器IP地址
      InetAddress  inetaddr=InetAddress.getByName(url.getHost());
      Socket  m_socket;
      //屏幕顯示服務(wù)器IP地址、通訊協(xié)議
      System.out.println("服務(wù)器:"+inetaddr+" "+url.getHost()+" "+url.getProtocol());
      m_socket=new Socket(inetaddr,8000); //創(chuàng)建與服務(wù)器IP地址連接的套接口
      //在套接口上建立輸入流
      m_in=new  DataInputStream(m_socket.getInputStream());
      //在套接口上建立輸出流
      m_out=new DataOutputStream(m_socket.getOutputStream());
    }
    catch (Exception e)
    {
      System.out.println("Error:"+e);
    }
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception {
    jLabel1.setFont(new java.awt.Font("DialogInput", 1, 20));
    jLabel1.setForeground(Color.red);
    jLabel1.setToolTipText("作者：楊林森  Email:yanglinsen@126.com");
    jLabel1.setText("一對(duì)多聊天程序Java Applet客戶(hù)端");
    jLabel1.setBounds(new Rectangle(81, 22, 358, 38));
    this.setBackground(UIManager.getColor("ComboBox.selectionBackground"));
    this.setLayout(null);
    jLabel2.setFont(new java.awt.Font("Dialog", 1, 16));
    jLabel2.setForeground(Color.blue);
    jLabel2.setText("輸入發(fā)送消息：");
    jLabel2.setBounds(new Rectangle(35, 78, 124, 37));
    jButton1.setBackground(UIManager.getColor("OptionPane.questionDialog.titlePane.background"));
    jButton1.setBounds(new Rectangle(413, 77, 70, 39));
    jButton1.setFont(new java.awt.Font("Dialog", 1, 16));
    jButton1.setForeground(Color.blue);
    jButton1.setToolTipText("點(diǎn)擊發(fā)送按鈕即可發(fā)送文本框中輸入的消息");
    jButton1.setText("發(fā)送");
    jButton1.addActionListener(new ChatClientApplet_jButton1_actionAdapter(this));
    jTextField1.setBackground(new Color(182, 231, 223));
    jTextField1.setFont(new java.awt.Font("Dialog", 0, 17));
    jTextField1.setToolTipText("此文本框用來(lái)輸入發(fā)送的消息");
    jTextField1.setBounds(new Rectangle(153, 80, 248, 35));
    jScrollPane1.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    jScrollPane1.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    jScrollPane1.getViewport().setBackground(UIManager.getColor("MenuItem.acceleratorForeground"));
    jScrollPane1.setBounds(new Rectangle(54, 130, 410, 231));
    jTextArea1.setBackground(UIManager.getColor("Desktop.background"));
    jTextArea1.setFont(new java.awt.Font("Dialog", 0, 18));
    jTextArea1.setForeground(Color.black);
    jLabel3.setFont(new java.awt.Font("Dialog", 0, 16));
    jLabel3.setForeground(Color.blue);
    jLabel3.setText("如想離開(kāi)聊天室，可在發(fā)送框中輸入字符串leave并發(fā)送");
    jLabel3.setBounds(new Rectangle(62, 367, 394, 24));
    this.add(jLabel1, null);
    this.add(jLabel2, null);
    this.add(jTextField1, null);
    this.add(jButton1, null);
    this.add(jScrollPane1, null);
    this.add(jLabel3, null);
    jScrollPane1.getViewport().add(jTextArea1, null);
    //啟動(dòng)監(jiān)聽(tīng)線(xiàn)程
    new Thread(this).start();
  }
  //Get Applet information
  public String getAppletInfo() {
    return "Applet Information";
  }
  //Get parameter info
  public String[][] getParameterInfo() {
    return null;
  }
  public void run()
    {
        try
        {
            while(true)
            {
             //監(jiān)聽(tīng)服務(wù)者發(fā)來(lái)的消息，線(xiàn)程將阻塞在該語(yǔ)句中，直到消息到來(lái)。
                String s=m_in.readUTF();  //讀一個(gè)UTF格式字符串。
                if(s!=null)
                //將消息顯示在信息顯示窗口中。
                jTextArea1.append(s+"\n");
            }
        }
            catch(Exception e)
            {
                jTextArea1.append("Network problem or Sever down.\n");
                jTextArea1.setVisible(false);
            }
        }
        public void stop()
        {
           try
           {
              m_out.writeUTF("leave");
              //如想離開(kāi)聊天室，可在發(fā)送框中輸入字符串leave
           }
           catch(IOException e){}
        }

    void jButton1_actionPerformed(ActionEvent e){
      String b = jTextField1.getText();
      jTextField1.setText("");
      //將用戶(hù)輸入的消息發(fā)送給 Chat Server
      try{
        m_out.writeUTF(b); //向服務(wù)者發(fā)送一UTF格式字符串。
      }
      catch(IOException g){}
    }
}

class ChatClientApplet_jButton1_actionAdapter implements java.awt.event.ActionListener {
  ChatClientApplet adaptee;

  ChatClientApplet_jButton1_actionAdapter(ChatClientApplet adaptee) {
    this.adaptee = adaptee;
  }
  public void actionPerformed(ActionEvent e) {
    adaptee.jButton1_actionPerformed(e);
  }
}