java基于NIO实现群聊模式

Java基于NIO实现群聊模式攻略

简介

Java NIO（New I/O）是Java 1.4版本引入的一组用于高效处理I/O操作的API。使用Java NIO，我们可以实现非阻塞的、事件驱动的I/O操作，这对于实现群聊模式非常有用。在本攻略中，我们将使用Java NIO来实现一个简单的群聊程序。

步骤

步骤1：创建服务器端

首先，我们需要创建一个服务器端来接收客户端的连接，并将接收到的消息广播给所有连接的客户端。

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;

public class Server {
    private Selector selector;
    private ServerSocketChannel serverSocketChannel;
    private ByteBuffer buffer = ByteBuffer.allocate(1024);

    public void start(int port) throws IOException {
        selector = Selector.open();
        serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false);
        serverSocketChannel.bind(new InetSocketAddress(port));
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        System.out.println(\"Server started on port \" + port);

        while (true) {
            selector.select();
            Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                iterator.remove();

                if (key.isAcceptable()) {
                    acceptConnection(key);
                } else if (key.isReadable()) {
                    broadcastMessage(key);
                }
            }
        }
    }

    private void acceptConnection(SelectionKey key) throws IOException {
        ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
        SocketChannel clientChannel = serverChannel.accept();
        clientChannel.configureBlocking(false);
        clientChannel.register(selector, SelectionKey.OP_READ);
        System.out.println(\"New client connected: \" + clientChannel.getRemoteAddress());
    }

    private void broadcastMessage(SelectionKey key) throws IOException {
        SocketChannel clientChannel = (SocketChannel) key.channel();
        buffer.clear();
        int bytesRead = clientChannel.read(buffer);
        if (bytesRead == -1) {
            clientChannel.close();
            return;
        }
        buffer.flip();
        byte[] bytes = new byte[buffer.remaining()];
        buffer.get(bytes);
        String message = new String(bytes);
        System.out.println(\"Received message: \" + message);

        for (SelectionKey selectionKey : selector.keys()) {
            Channel channel = selectionKey.channel();
            if (channel instanceof SocketChannel && channel != clientChannel) {
                SocketChannel destChannel = (SocketChannel) channel;
                destChannel.write(ByteBuffer.wrap(bytes));
            }
        }
    }

    public static void main(String[] args) throws IOException {
        Server server = new Server();
        server.start(8080);
    }
}

步骤2：创建客户端

接下来，我们需要创建一个客户端来连接服务器，并发送和接收消息。

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Scanner;

public class Client {
    private SocketChannel socketChannel;
    private ByteBuffer buffer = ByteBuffer.allocate(1024);

    public void start(String serverHost, int serverPort) throws IOException {
        socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(false);
        socketChannel.connect(new InetSocketAddress(serverHost, serverPort));

        while (!socketChannel.finishConnect()) {
            // 等待连接完成
        }

        System.out.println(\"Connected to server: \" + socketChannel.getRemoteAddress());

        new Thread(() -> {
            try {
                while (true) {
                    buffer.clear();
                    int bytesRead = socketChannel.read(buffer);
                    if (bytesRead == -1) {
                        socketChannel.close();
                        return;
                    }
                    buffer.flip();
                    byte[] bytes = new byte[buffer.remaining()];
                    buffer.get(bytes);
                    String message = new String(bytes);
                    System.out.println(\"Received message: \" + message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }).start();

        Scanner scanner = new Scanner(System.in);
        while (true) {
            String message = scanner.nextLine();
            if (message.equalsIgnoreCase(\"exit\")) {
                socketChannel.close();
                break;
            }
            buffer.clear();
            buffer.put(message.getBytes());
            buffer.flip();
            socketChannel.write(buffer);
        }
    }

    public static void main(String[] args) throws IOException {
        Client client = new Client();
        client.start(\"localhost\", 8080);
    }
}

示例说明

示例1：运行服务器端

Server server = new Server();
server.start(8080);

示例2：运行客户端

Client client = new Client();
client.start(\"localhost\", 8080);

在示例2中，客户端将连接到本地主机的8080端口，并可以发送和接收消息。在服务器端示例1中，服务器将监听8080端口，并将接收到的消息广播给所有连接的客户端。

请注意，示例中的代码仅为演示目的，可能需要根据实际需求进行修改和扩展。