Java Socket实现多人聊天室---swing做UI

今天翻硬盘的workspace发现一个Java Socket实现多人聊天室的源码，不记得是什么时候的事情了，貌似不是我写的。但写得还不错，

至少算个有模有样的聊天室工具。我简单的修改了一下，拿出来跟大家分享一下，仅供参考。。。

界面是用swing写的，还不懒，简约大方。有图有真相：

正如上图所示，这个程序分为 服务器端和客户端，说白了就是 两个main class，用eclipse直接运行之。。。。。

聊天室的设计思想是 ：在局域网下， 利用socket进行连接通信，当服务器端启动的时候，利用Thread线程不停的等待客户端的链接；当有客户端开启连

接的时候，服务器端通过IO流反馈“上线用户”信息给客户端，客户端也使用线程不停的接收服务器的信息，从而实现多人在线聊天功能。

程序中有三个类，分别 Server.java（服务器端）、Client（客户端）、User.java（javabean）。代码如下：

Server.java（服务器端）：

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();
				}
			}
		}
	}
}

Client（客户端）：

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();
				}
			}
		}
	}
}

User.java

//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;
	}
}

注： 在eclipse下运行无需另外添加jar文件，其中服务器端和客户端均需要一张图片做icon，大家可以随便找张图片补上。

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