socket即时聊天

服务端

package com.luhan.text;
import java.awt.BorderLayout;  
import java.awt.Color;  
import java.awt.GridLayout;  
import java.awt.Toolkit;  
import java.awt.event.ActionEvent;  
import java.awt.event.ActionListener;  
import java.awt.event.WindowAdapter;  
import java.awt.event.WindowEvent;  
import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.BindException;  
import java.net.ServerSocket;  
import java.net.Socket;  
import java.util.ArrayList;  
import java.util.StringTokenizer;  
  
import javax.swing.DefaultListModel;  
import javax.swing.JButton;  
import javax.swing.JFrame;  
import javax.swing.JLabel;  
import javax.swing.JList;  
import javax.swing.JOptionPane;  
import javax.swing.JPanel;  
import javax.swing.JScrollPane;  
import javax.swing.JSplitPane;  
import javax.swing.JTextArea;  
import javax.swing.JTextField;  
import javax.swing.border.TitledBorder;  
  
public class Server {  
  
    private JFrame frame;  
    private JTextArea contentArea;  
    private JTextField txt_message;  
    private JTextField txt_max;  
    private JTextField txt_port;  
    private JButton btn_start;  
    private JButton btn_stop;  
    private JButton btn_send;  
    private JPanel northPanel;  
    private JPanel southPanel;  
    private JScrollPane rightPanel;  
    private JScrollPane leftPanel;  
    private JSplitPane centerSplit;  
    private JList userList;  
    private DefaultListModel listModel;  
  
    private ServerSocket serverSocket;  
    private ServerThread serverThread;  
    private ArrayList<ClientThread> clients;  
  
    private boolean isStart = false;  
  
    // 主方法,程序执行入口  
    public static void main(String[] args) {  
        new Server();  
    }  
  
    // 执行消息发送  
    public void send() {  
        if (!isStart) {  
            JOptionPane.showMessageDialog(frame, "服务器还未启动,不能发送消息！", "错误",  
                    JOptionPane.ERROR_MESSAGE);  
            return;  
        }  
        if (clients.size() == 0) {  
            JOptionPane.showMessageDialog(frame, "没有用户在线,不能发送消息！", "错误",  
                    JOptionPane.ERROR_MESSAGE);  
            return;  
        }  
        String message = txt_message.getText().trim();  
        if (message == null || message.equals("")) {  
            JOptionPane.showMessageDialog(frame, "消息不能为空！", "错误",  
                    JOptionPane.ERROR_MESSAGE);  
            return;  
        }  
        sendServerMessage(message);// 群发服务器消息  
        contentArea.append("服务器说：" + txt_message.getText() + "\r\n");  
        txt_message.setText(null);  
    }  
  
    // 构造放法  
    public Server() {  
        frame = new JFrame("服务器");  
        // 更改JFrame的图标：  
        //frame.setIconImage(Toolkit.getDefaultToolkit().createImage(Client.class.getResource("qq.png")));  
        //frame.setIconImage(Toolkit.getDefaultToolkit().createImage(Server.class.getResource("qq.png")));  
        contentArea = new JTextArea();  
        contentArea.setEditable(false);  
        contentArea.setForeground(Color.blue);  
        txt_message = new JTextField();  
        txt_max = new JTextField("30");  
        txt_port = new JTextField("6666");  
        btn_start = new JButton("启动");  
        btn_stop = new JButton("停止");  
        btn_send = new JButton("发送");  
        btn_stop.setEnabled(false);  
        listModel = new DefaultListModel();  
        userList = new JList(listModel);  
  
        southPanel = new JPanel(new BorderLayout());  
        southPanel.setBorder(new TitledBorder("写消息"));  
        southPanel.add(txt_message, "Center");  
        southPanel.add(btn_send, "East");  
        leftPanel = new JScrollPane(userList);  
        leftPanel.setBorder(new TitledBorder("在线用户"));  
  
        rightPanel = new JScrollPane(contentArea);  
        rightPanel.setBorder(new TitledBorder("消息显示区"));  
  
        centerSplit = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel,  
                rightPanel);  
        centerSplit.setDividerLocation(100);  
        northPanel = new JPanel();  
        northPanel.setLayout(new GridLayout(1, 6));  
        northPanel.add(new JLabel("人数上限"));  
        northPanel.add(txt_max);  
        northPanel.add(new JLabel("端口"));  
        northPanel.add(txt_port);  
        northPanel.add(btn_start);  
        northPanel.add(btn_stop);  
        northPanel.setBorder(new TitledBorder("配置信息"));  
  
        frame.setLayout(new BorderLayout());  
        frame.add(northPanel, "North");  
        frame.add(centerSplit, "Center");  
        frame.add(southPanel, "South");  
        frame.setSize(600, 400);  
        //frame.setSize(Toolkit.getDefaultToolkit().getScreenSize());//设置全屏  
        int screen_width = Toolkit.getDefaultToolkit().getScreenSize().width;  
        int screen_height = Toolkit.getDefaultToolkit().getScreenSize().height;  
        frame.setLocation((screen_width - frame.getWidth()) / 2,  
                (screen_height - frame.getHeight()) / 2);  
        frame.setVisible(true);  
  
        // 关闭窗口时事件  
        frame.addWindowListener(new WindowAdapter() {  
            public void windowClosing(WindowEvent e) {  
                if (isStart) {  
                    closeServer();// 关闭服务器  
                }  
                System.exit(0);// 退出程序  
            }  
        });  
  
        // 文本框按回车键时事件  
        txt_message.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                send();  
            }  
        });  
  
        // 单击发送按钮时事件  
        btn_send.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent arg0) {  
                send();  
            }  
        });  
  
        // 单击启动服务器按钮时事件  
        btn_start.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                if (isStart) {  
                    JOptionPane.showMessageDialog(frame, "服务器已处于启动状态，不要重复启动！",  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                    return;  
                }  
                int max;  
                int port;  
                try {  
                    try {  
                        max = Integer.parseInt(txt_max.getText());  
                    } catch (Exception e1) {  
                        throw new Exception("人数上限为正整数！");  
                    }  
                    if (max <= 0) {  
                        throw new Exception("人数上限为正整数！");  
                    }  
                    try {  
                        port = Integer.parseInt(txt_port.getText());  
                    } catch (Exception e1) {  
                        throw new Exception("端口号为正整数！");  
                    }  
                    if (port <= 0) {  
                        throw new Exception("端口号 为正整数！");  
                    }  
                    serverStart(max, port);  
                    contentArea.append("服务器已成功启动!人数上限：" + max + ",端口：" + port  
                            + "\r\n");  
                    JOptionPane.showMessageDialog(frame, "服务器成功启动!");  
                    btn_start.setEnabled(false);  
                    txt_max.setEnabled(false);  
                    txt_port.setEnabled(false);  
                    btn_stop.setEnabled(true);  
                } catch (Exception exc) {  
                    JOptionPane.showMessageDialog(frame, exc.getMessage(),  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                }  
            }  
        });  
  
        // 单击停止服务器按钮时事件  
        btn_stop.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                if (!isStart) {  
                    JOptionPane.showMessageDialog(frame, "服务器还未启动，无需停止！", "错误",  
                            JOptionPane.ERROR_MESSAGE);  
                    return;  
                }  
                try {  
                    closeServer();  
                    btn_start.setEnabled(true);  
                    txt_max.setEnabled(true);  
                    txt_port.setEnabled(true);  
                    btn_stop.setEnabled(false);  
                    contentArea.append("服务器成功停止!\r\n");  
                    JOptionPane.showMessageDialog(frame, "服务器成功停止！");  
                } catch (Exception exc) {  
                    JOptionPane.showMessageDialog(frame, "停止服务器发生异常！", "错误",  
                            JOptionPane.ERROR_MESSAGE);  
                }  
            }  
        });  
    }  
  
    // 启动服务器  
    public void serverStart(int max, int port) throws java.net.BindException {  
        try {  
            clients = new ArrayList<ClientThread>();  
            serverSocket = new ServerSocket(port);
            serverThread = new ServerThread(serverSocket, max);  
            serverThread.start();  
            isStart = true;  
        } catch (BindException e) {  
            isStart = false;  
            throw new BindException("端口号已被占用，请换一个！");  
        } catch (Exception e1) {  
            e1.printStackTrace();  
            isStart = false;  
            throw new BindException("启动服务器异常！");  
        }  
    }  
  
    // 关闭服务器  
    @SuppressWarnings("deprecation")  
    public void closeServer() {  
        try {  
            if (serverThread != null)  
                serverThread.stop();// 停止服务器线程  
  
            for (int i = clients.size() - 1; i >= 0; i--) {  
                // 给所有在线用户发送关闭命令  
                clients.get(i).getWriter().println("CLOSE");  
                clients.get(i).getWriter().flush();  
                // 释放资源  
                clients.get(i).stop();// 停止此条为客户端服务的线程  
                clients.get(i).reader.close();  
                clients.get(i).writer.close();  
                clients.get(i).socket.close();  
                clients.remove(i);  
            }  
            if (serverSocket != null) {  
                serverSocket.close();// 关闭服务器端连接  
            }  
            listModel.removeAllElements();// 清空用户列表  
            isStart = false;  
        } catch (IOException e) {  
            e.printStackTrace();  
            isStart = true;  
        }  
    }  
  
    // 群发服务器消息  
    public void sendServerMessage(String message) {  
        for (int i = clients.size() - 1; i >= 0; i--) {  
            clients.get(i).getWriter().println("服务器：" + message + "(多人发送)");  
            clients.get(i).getWriter().flush();  
        }  
    }  
  
    // 服务器线程  
    class ServerThread extends Thread {  
        private ServerSocket serverSocket;  
        private int max;// 人数上限  
  
        // 服务器线程的构造方法  
        public ServerThread(ServerSocket serverSocket, int max) {  
            this.serverSocket = serverSocket;  
            this.max = max;  
        }  
  
        public void run() {  
            while (true) {// 不停的等待客户端的链接  
                try {  
                    Socket socket = serverSocket.accept();  
                    if (clients.size() == max) {// 如果已达人数上限  
                        BufferedReader r = new BufferedReader(  
                                new InputStreamReader(socket.getInputStream()));  
                        PrintWriter w = new PrintWriter(socket  
                                .getOutputStream());  
                        // 接收客户端的基本用户信息  
                        String inf = r.readLine();  
                        StringTokenizer st = new StringTokenizer(inf, "@");  
                        User user = new User(st.nextToken(), st.nextToken());  
                        // 反馈连接成功信息  
                        w.println("MAX@服务器：对不起，" + user.getName()  
                                + user.getIp() + "，服务器在线人数已达上限，请稍后尝试连接！");  
                        w.flush();  
                        // 释放资源  
                        r.close();  
                        w.close();  
                        socket.close();  
                        continue;  
                    }  
                    ClientThread client = new ClientThread(socket);  
                    client.start();// 开启对此客户端服务的线程  
                    clients.add(client);  
                    listModel.addElement(client.getUser().getName());// 更新在线列表  
                    contentArea.append(client.getUser().getName()  
                            + client.getUser().getIp() + "上线!\r\n");  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    }  
  
    // 为一个客户端服务的线程  
    class ClientThread extends Thread {  
        private Socket socket;  
        private BufferedReader reader;  
        private PrintWriter writer;  
        private User user;  
  
        public BufferedReader getReader() {  
            return reader;  
        }  
  
        public PrintWriter getWriter() {  
            return writer;  
        }  
  
        public User getUser() {  
            return user;  
        }  
  
        // 客户端线程的构造方法  
        public ClientThread(Socket socket) {  
            try {  
                this.socket = socket;  
                reader = new BufferedReader(new InputStreamReader(socket  
                        .getInputStream()));  
                writer = new PrintWriter(socket.getOutputStream());  
                // 接收客户端的基本用户信息  
                String inf = reader.readLine();  
                StringTokenizer st = new StringTokenizer(inf, "@");
                user = new User(st.nextToken(), st.nextToken());  
                // 反馈连接成功信息  
                writer.println(user.getName() + user.getIp() + "与服务器连接成功!");  
                writer.flush();  
                // 反馈当前在线用户信息  
                if (clients.size() > 0) {  
                    String temp = "";  
                    for (int i = clients.size() - 1; i >= 0; i--) {  
                        temp += (clients.get(i).getUser().getName() + "/" + clients  
                                .get(i).getUser().getIp())  
                                + "@";  
                    }  
                    writer.println("USERLIST@" + clients.size() + "@" + temp);  
                    writer.flush();  
                }  
                // 向所有在线用户发送该用户上线命令  
                for (int i = clients.size() - 1; i >= 0; i--) {  
                    clients.get(i).getWriter().println(  
                            "ADD@" + user.getName() + user.getIp());  
                    clients.get(i).getWriter().flush();  
                }  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
  
        @SuppressWarnings("deprecation")  
        public void run() {// 不断接收客户端的消息，进行处理。  
            String message = null;  
            while (true) {  
                try {  
                    message = reader.readLine();// 接收客户端消息 
                    if (message.equals("CLOSE"))// 下线命令  
                    {  
                        contentArea.append(this.getUser().getName()  
                                + this.getUser().getIp() + "下线!\r\n");  
                        // 断开连接释放资源  
                        reader.close();  
                        writer.close();  
                        socket.close();  
  
                        // 向所有在线用户发送该用户的下线命令  
                        for (int i = clients.size() - 1; i >= 0; i--) {  
                            clients.get(i).getWriter().println(  
                                    "DELETE@" + user.getName());  
                            clients.get(i).getWriter().flush();  
                        }  
  
                        listModel.removeElement(user.getName());// 更新在线列表  
  
                        // 删除此条客户端服务线程  
                        for (int i = clients.size() - 1; i >= 0; i--) {  
                            if (clients.get(i).getUser() == user) {  
                                ClientThread temp = clients.get(i);  
                                clients.remove(i);// 删除此用户的服务线程  
                                temp.stop();// 停止这条服务线程  
                                return;  
                            }  
                        }  
                    } else {  
                        dispatcherMessage(message);// 转发消息  
                    }  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }
        // 转发消息  
        public void dispatcherMessage(String message) {  
            StringTokenizer stringTokenizer = new StringTokenizer(message, "@");  
            String source = stringTokenizer.nextToken();  
            String owner = stringTokenizer.nextToken();  
            String content = stringTokenizer.nextToken();  
            message = source + "说：" + content;  
            contentArea.append(message + "\r\n");  
            if (owner.equals("ALL")) {// 群发  
                for (int i = clients.size() - 1; i >= 0; i--) {  
                    clients.get(i).getWriter().println(message + "(多人发送)");  
                    clients.get(i).getWriter().flush();  
                }  
            }  
        }  
    }  
}

客户端

package com.luhan.text;

import java.awt.BorderLayout;  
import java.awt.Color;  
import java.awt.GridLayout;  
import java.awt.Toolkit;  
import java.awt.event.ActionEvent;  
import java.awt.event.ActionListener;  
import java.awt.event.WindowAdapter;  
import java.awt.event.WindowEvent;  
import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.Socket;  
import java.util.HashMap;  
import java.util.Map;  
import java.util.StringTokenizer;  
  
import javax.swing.DefaultListModel;  
import javax.swing.JButton;  
import javax.swing.JFrame;  
import javax.swing.JLabel;  
import javax.swing.JList;  
import javax.swing.JOptionPane;  
import javax.swing.JPanel;  
import javax.swing.JScrollPane;  
import javax.swing.JSplitPane;  
import javax.swing.JTextArea;  
import javax.swing.JTextField;  
import javax.swing.border.TitledBorder;  
  
public class Client{  
  
    private JFrame frame;  
    private JList userList;  
    private JTextArea textArea;  
    private JTextField textField;  
    private JTextField txt_port;  
    private JTextField txt_hostIp;  
    private JTextField txt_name;  
    private JButton btn_start;  
    private JButton btn_stop;  
    private JButton btn_send;  
    private JPanel northPanel;  
    private JPanel southPanel;  
    private JScrollPane rightScroll;  
    private JScrollPane leftScroll;  
    private JSplitPane centerSplit;  
  
    private DefaultListModel listModel;  
    private boolean isConnected = false;  
  
    private Socket socket;  
    private PrintWriter writer;  
    private BufferedReader reader;  
    private MessageThread messageThread;// 负责接收消息的线程  
    private Map<String, User> onLineUsers = new HashMap<String, User>();// 所有在线用户  
  
    // 主方法,程序入口  
    public static void main(String[] args) {  
        new Client();  
    }  
  
    // 执行发送  
    public void send() {  
        if (!isConnected) {  
            JOptionPane.showMessageDialog(frame, "还没有连接服务器，无法发送消息！", "错误",  
                    JOptionPane.ERROR_MESSAGE);  
            return;  
        }  
        String message = textField.getText().trim();  
        if (message == null || message.equals("")) {  
            JOptionPane.showMessageDialog(frame, "消息不能为空！", "错误",  
                    JOptionPane.ERROR_MESSAGE);  
            return;  
        }  
        sendMessage(frame.getTitle() + "@" + "ALL" + "@" + message);  
        textField.setText(null);  
    }  
  
    // 构造方法  
    public Client() {  
        textArea = new JTextArea();  
        textArea.setEditable(false);  
        textArea.setForeground(Color.blue);  
        textField = new JTextField();  
        txt_port = new JTextField("6666");  
        txt_hostIp = new JTextField("127.0.0.1");  
        txt_name = new JTextField("xiaoqiang");  
        btn_start = new JButton("连接");  
        btn_stop = new JButton("断开");  
        btn_send = new JButton("发送");  
        listModel = new DefaultListModel();  
        userList = new JList(listModel);  
  
        northPanel = new JPanel();  
        northPanel.setLayout(new GridLayout(1, 7));  
        northPanel.add(new JLabel("端口"));  
        northPanel.add(txt_port);  
        northPanel.add(new JLabel("服务器IP"));  
        northPanel.add(txt_hostIp);  
        northPanel.add(new JLabel("姓名"));  
        northPanel.add(txt_name);  
        northPanel.add(btn_start);  
        northPanel.add(btn_stop);  
        northPanel.setBorder(new TitledBorder("连接信息"));  
  
        rightScroll = new JScrollPane(textArea);  
        rightScroll.setBorder(new TitledBorder("消息显示区"));  
        leftScroll = new JScrollPane(userList);  
        leftScroll.setBorder(new TitledBorder("在线用户"));  
        southPanel = new JPanel(new BorderLayout());  
        southPanel.add(textField, "Center");  
        southPanel.add(btn_send, "East");  
        southPanel.setBorder(new TitledBorder("写消息"));  
  
        centerSplit = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftScroll,  
                rightScroll);  
        centerSplit.setDividerLocation(100);  
  
        frame = new JFrame("客户机");  
        // 更改JFrame的图标：  
        //frame.setIconImage(Toolkit.getDefaultToolkit().createImage(Client.class.getResource("qq.png")));  
        frame.setLayout(new BorderLayout());  
        frame.add(northPanel, "North");  
        frame.add(centerSplit, "Center");  
        frame.add(southPanel, "South");  
        frame.setSize(600, 400);  
        int screen_width = Toolkit.getDefaultToolkit().getScreenSize().width;  
        int screen_height = Toolkit.getDefaultToolkit().getScreenSize().height;  
        frame.setLocation((screen_width - frame.getWidth()) / 2,  
                (screen_height - frame.getHeight()) / 2);  
        frame.setVisible(true);  
  
        // 写消息的文本框中按回车键时事件  
        textField.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent arg0) {  
                send();  
            }  
        });  
  
        // 单击发送按钮时事件  
        btn_send.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                send();  
            }  
        });  
  
        // 单击连接按钮时事件  
        btn_start.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                int port;  
                if (isConnected) {  
                    JOptionPane.showMessageDialog(frame, "已处于连接上状态，不要重复连接!",  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                    return;  
                }  
                try {  
                    try {  
                        port = Integer.parseInt(txt_port.getText().trim());  
                    } catch (NumberFormatException e2) {  
                        throw new Exception("端口号不符合要求!端口为整数!");  
                    }  
                    String hostIp = txt_hostIp.getText().trim();  
                    String name = txt_name.getText().trim();  
                    if (name.equals("") || hostIp.equals("")) {  
                        throw new Exception("姓名、服务器IP不能为空!");  
                    }  
                    boolean flag = connectServer(port, hostIp, name);  
                    if (flag == false) {  
                        throw new Exception("与服务器连接失败!");  
                    }  
                    frame.setTitle(name);  
                    JOptionPane.showMessageDialog(frame, "成功连接!");  
                } catch (Exception exc) {  
                    JOptionPane.showMessageDialog(frame, exc.getMessage(),  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                }  
            }  
        });  
  
        // 单击断开按钮时事件  
        btn_stop.addActionListener(new ActionListener() {  
            public void actionPerformed(ActionEvent e) {  
                if (!isConnected) {  
                    JOptionPane.showMessageDialog(frame, "已处于断开状态，不要重复断开!",  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                    return;  
                }  
                try {  
                    boolean flag = closeConnection();// 断开连接  
                    if (flag == false) {  
                        throw new Exception("断开连接发生异常！");  
                    }  
                    JOptionPane.showMessageDialog(frame, "成功断开!");  
                } catch (Exception exc) {  
                    JOptionPane.showMessageDialog(frame, exc.getMessage(),  
                            "错误", JOptionPane.ERROR_MESSAGE);  
                }  
            }  
        });  
  
        // 关闭窗口时事件  
        frame.addWindowListener(new WindowAdapter() {  
            public void windowClosing(WindowEvent e) {  
                if (isConnected) {  
                    closeConnection();// 关闭连接  
                }  
                System.exit(0);// 退出程序  
            }  
        });  
    }
    /**  
     * 连接服务器  
     *   
     * @param port  
     * @param hostIp  
     * @param name  
     */  
    public boolean connectServer(int port, String hostIp, String name) {  
        // 连接服务器  
        try {  
            socket = new Socket(hostIp, port);// 根据端口号和服务器ip建立连接  
            writer = new PrintWriter(socket.getOutputStream());  
            reader = new BufferedReader(new InputStreamReader(socket  
                    .getInputStream()));  
            // 发送客户端用户基本信息(用户名和ip地址)  
            sendMessage(name + "@" + socket.getLocalAddress().toString());  
            // 开启接收消息的线程  
            messageThread = new MessageThread(reader, textArea);  
            messageThread.start();
            isConnected = true;// 已经连接上了  
            return true;  
        } catch (Exception e) {
            textArea.append("与端口号为：" + port + "    IP地址为：" + hostIp  
                    + "   的服务器连接失败!" + "\r\n");  
            isConnected = false;// 未连接上  
            return false;  
        }  
    }  
  
    /**  
     * 发送消息  
     *   
     * @param message  
     */  
    public void sendMessage(String message) {  
        writer.println(message);  
        writer.flush();  
    }
    /**  
     * 客户端主动关闭连接  
     */  
    @SuppressWarnings("deprecation")  
    public synchronized boolean closeConnection() {  
        try {  
            sendMessage("CLOSE");// 发送断开连接命令给服务器  
            messageThread.stop();// 停止接受消息线程  
            // 释放资源  
            if (reader != null) {  
                reader.close();  
            }  
            if (writer != null) {  
                writer.close();  
            }  
            if (socket != null) {  
                socket.close();  
            }  
            isConnected = false;  
            return true;  
        } catch (IOException e1) {  
            e1.printStackTrace();  
            isConnected = true;  
            return false;  
        }  
    }  
  
    // 不断接收消息的线程  
    class MessageThread extends Thread {  
        private BufferedReader reader;  
        private JTextArea textArea;  
  
        // 接收消息线程的构造方法  
        public MessageThread(BufferedReader reader, JTextArea textArea) {  
            this.reader = reader;  
            this.textArea = textArea;  
        }  
  
        // 被动的关闭连接  
        public synchronized void closeCon() throws Exception {  
            // 清空用户列表  
            listModel.removeAllElements();  
            // 被动的关闭连接释放资源  
            if (reader != null) {  
                reader.close();  
            }  
            if (writer != null) {  
                writer.close();  
            }  
            if (socket != null) {  
                socket.close();  
            }  
            isConnected = false;// 修改状态为断开  
        }  
  
        public void run() {  
            String message = "";  
            while (true) {  
                try {  
                    message = reader.readLine();  
                    StringTokenizer stringTokenizer = new StringTokenizer(  
                            message, "/@");
                    String command = stringTokenizer.nextToken();// 命令  
                    if (command.equals("CLOSE"))// 服务器已关闭命令  
                    {  
                        textArea.append("服务器已关闭!\r\n");  
                        closeCon();// 被动的关闭连接  
                        return;// 结束线程  
                    } else if (command.equals("ADD")) {// 有用户上线更新在线列表  
                        String username = "";  
                        String userIp = "";  
                        if ((username = stringTokenizer.nextToken()) != null  
                                && (userIp = stringTokenizer.nextToken()) != null) {  
                            User user = new User(username, userIp);  
                            onLineUsers.put(username, user);  
                            listModel.addElement(username);  
                        }  
                    } else if (command.equals("DELETE")) {// 有用户下线更新在线列表  
                        String username = stringTokenizer.nextToken();  
                        User user = (User) onLineUsers.get(username);  
                        onLineUsers.remove(user);  
                        listModel.removeElement(username);  
                    } else if (command.equals("USERLIST")) {// 加载在线用户列表  
                        int size = Integer  
                                .parseInt(stringTokenizer.nextToken());  
                        String username = null;  
                        String userIp = null;  
                        for (int i = 0; i < size; i++) {  
                            username = stringTokenizer.nextToken();  
                            userIp = stringTokenizer.nextToken();  
                            User user = new User(username, userIp);  
                            onLineUsers.put(username, user);  
                            listModel.addElement(username);  
                        }  
                    } else if (command.equals("MAX")) {// 人数已达上限  
                        textArea.append(stringTokenizer.nextToken()  
                                + stringTokenizer.nextToken() + "\r\n");  
                        closeCon();// 被动的关闭连接  
                        JOptionPane.showMessageDialog(frame, "服务器缓冲区已满！", "错误",  
                                JOptionPane.ERROR_MESSAGE);  
                        return;// 结束线程  
                    } else {// 普通消息  
                        textArea.append(message + "\r\n");  
                    }  
                } catch (IOException e) {  
                    e.printStackTrace();  
                } catch (Exception e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    }  
}

实体类

package com.luhan.text;

//用户信息类  
public class User{  
  private String name;  
  private String ip;  

  public User(String name, String ip) {  
      this.name = name;  
      this.ip = ip;  
  }  

  public String getName() {  
      return name;  
  }  

  public void setName(String name) {  
      this.name = name;  
  }  

  public String getIp() {  
      return ip;  
  }  

  public void setIp(String ip) {  
      this.ip = ip;  
  }  
}