聊天室（Java实现）

聊天室是一个基于网络的多人聊天室，用户可以通过它与其他用户进行实时聊天。下面是一个使用 Java 实现的简单聊天室。

1. 服务器端

服务器端需要监听客户端的请求，并将消息转发给所有连接的客户端。以下是服务器端的代码：

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class ChatServer {
    private List<ClientThread> clients = new ArrayList<>();
    private ServerSocket serverSocket;

    public ChatServer(int port) {
        try {
            serverSocket = new ServerSocket(port);
            System.out.println("Server started on port " + port);
            while (true) {
                Socket clientSocket = serverSocket.accept();
                ClientThread client = new ClientThread(this, clientSocket);
                clients.add(client);
                client.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void broadcast(String message) {
        for (ClientThread client : clients) {
            client.sendMessage(message);
        }
    }

    public void removeClient(ClientThread client) {
        clients.remove(client);
    }

    public static void main(String[] args) {
        ChatServer server = new ChatServer(12345);
    }
}

class ClientThread extends Thread {
    private ChatServer server;
    private Socket clientSocket;

    public ClientThread(ChatServer server, Socket clientSocket) {
        this.server = server;
        this.clientSocket = clientSocket;
    }

    public void run() {
        try {
            System.out.println("Client connected: " + clientSocket.getInetAddress().getHostAddress());
            while (true) {
                String message = Utils.receiveMessage(clientSocket);
                if (message == null) {
                    break;
                }
                server.broadcast(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            server.removeClient(this);
            Utils.close(clientSocket);
            System.out.println("Client disconnected: " + clientSocket.getInetAddress().getHostAddress());
        }
    }

    public void sendMessage(String message) {
        Utils.sendMessage(clientSocket, message);
    }
}

class Utils {
    public static String receiveMessage(Socket socket) throws IOException {
        byte[] buffer = new byte[1024];
        int length = socket.getInputStream().read(buffer);
        if (length == -1) {
            return null;
        }
        return new String(buffer, 0, length);
    }

    public static void sendMessage(Socket socket, String message) {
        try {
            socket.getOutputStream().write(message.getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close(Socket socket) {
        try {
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. 客户端

客户端需要连接到服务器端，并可以发送和接收消息。以下是客户端的代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

public class ChatClient {
    private Socket socket;
    private BufferedReader input;
    private BufferedReader serverInput;

    public ChatClient(String host, int port) {
        try {
            socket = new Socket(host, port);
            System.out.println("Connected to server " + host + " on port " + port);
            input = new BufferedReader(new InputStreamReader(System.in));
            serverInput = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            new Thread(() -> {
                while (true) {
                    try {
                        String message = serverInput.readLine();
                        if (message == null) {
                            break;
                        }
                        System.out.println(message);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                Utils.close(socket);
            }).start();
            while (true) {
                String message = input.readLine();
                if (message == null || message.equals("/quit")) {
                    break;
                }
                Utils.sendMessage(socket, message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        ChatClient client = new ChatClient("localhost", 12345);
    }
}

class Utils {
    public static void sendMessage(Socket socket, String message) {
        try {
            socket.getOutputStream().write(message.getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close(Socket socket) {
        try {
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以上是一个简单的聊天室的 Java 实现。你可以根据需要进行修改和扩展。