Resource sharing of Java development chat room video tutorials

"Shang Xuetang Java Development Chat Room Video Tutorial" is a small project explained in class in the primary course. Let everyone become familiar with socket network programming, multi-threading technology, etc. by completing a point-to-point LAN chat system.

Course playback address: http://www.php.cn/course/516.html

The teacher’s teaching style:

The teacher’s lectures are simple, clear, layer-by-layer analysis, interlocking, rigorous argumentation, rigorous structure, and use the logical power of thinking to attract students’ attention Strength, use reason to control the classroom teaching process. By listening to the teacher's lectures, students not only learn knowledge, but also receive thinking training, and are also influenced and influenced by the teacher's rigorous academic attitude

The more difficult point in this video is the java development chat room:

The design idea of ​​the chat room is: under the local area network, use socket for connection communication. When the server is started, use Thread thread to continue Waiting for the client's link; when a client opens the connection, the server feeds back the "online user" information to the client through the IO stream, and the client also uses threads to continuously receive information from the server. This enables multi-person online chat functionality.

There are three classes in the program, namely Server.Java (server-side), Client (client-side), and User.java (javabean). The code is as follows:

Server.java (server side):

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();  
                }  
            }  
        }  
    }  
}

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