用java代码写一个在线聊天室

好的，以下是一个简单的在线聊天室的 Java 代码实现，包括服务器端和客户端部分的代码。请注意，这只是一个简单的示例，您可以根据具体需求进行修改和完善。

服务器端代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

public class ChatServer {
    private ArrayList<PrintWriter> clients;

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

    public ChatServer() {
        clients = new ArrayList<>();
    }

    public void start() {
        try {
            ServerSocket serverSocket = new ServerSocket(8888);
            System.out.println("服务器已启动，等待客户端连接...");

            while (true) {
                Socket clientSocket = serverSocket.accept();
                System.out.println("客户端 " + clientSocket.getInetAddress().getHostAddress() + " 已连接");

                PrintWriter writer = new PrintWriter(clientSocket.getOutputStream());
                clients.add(writer);

                Thread thread = new Thread(new ClientHandler(clientSocket));
                thread.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private class ClientHandler implements Runnable {
        private Socket clientSocket;
        private BufferedReader reader;

        public ClientHandler(Socket clientSocket) {
            this.clientSocket = clientSocket;
            try {
                reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run() {
            String message;
            try {
                while ((message = reader.readLine()) != null) {
                    System.out.println("接收到消息：" + message);
                    broadcast(message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        private void broadcast(String message) {
            for (PrintWriter writer : clients) {
                writer.println(message);
                writer.flush();
            }
        }
    }
}

客户端代码：

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

public class ChatClient {
    private BufferedReader reader;
    private PrintWriter writer;

    public static void main(String[] args) {
        ChatClient client = new ChatClient();
        client.start();
    }

    public void start() {
        try {
            Socket socket = new Socket("localhost", 8888);
            System.out.println("已连接到服务器");

            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new PrintWriter(socket.getOutputStream());

            Thread thread = new Thread(new ServerHandler());
            thread.start();

            String message;
            BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
            while ((message = console.readLine()) != null) {
                writer.println(message);
                writer.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private class ServerHandler implements Runnable {
        public void run() {
            String message;
            try {
                while ((message = reader.readLine()) != null) {
                    System.out.println("收到消息：" + message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

请注意，以上代码仅供参考，您需要根据实际情况进行修改和完善。