基于Netty构建多人聊天室：服务器和客户端实现

基于 Netty 构建多人聊天室：服务器和客户端实现

本文提供了一个使用 Netty 库构建多人聊天室的完整示例，包括服务器和客户端的实现，以及用户登录、聊天室列表、消息发送和私聊功能的实现细节。

服务器端

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import io.netty.util.concurrent.EventExecutorGroup;

import java.util.concurrent.ConcurrentHashMap;

public class MultiChatServer {
    private final int port;
    private final ConcurrentHashMap<String, ChannelHandlerContext> userMap = new ConcurrentHashMap<>();
    private final EventExecutorGroup group = new DefaultEventExecutorGroup(16);

    public MultiChatServer(int port) {
        this.port = port;
    }

    public void run() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new StringDecoder(), new StringEncoder(), new MultiChatServerHandler(userMap, group));
                        }
                    })
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true);

            ChannelFuture f = b.bind(port).sync();
            System.out.println('Server started on port ' + port);
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        int port = 8080;
        new MultiChatServer(port).run();
    }
}

客户端

package org.example;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class MultiChatClient {
    private final String host;
    private final int port;
    private ChannelHandlerContext ctx;

    public MultiChatClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void run() throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.SO_KEEPALIVE, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new StringDecoder(), new StringEncoder(), new MultiChatClientHandler());
                        }
                    });
            ChannelFuture f = b.connect(host, port).sync();
            ctx = f.channel().pipeline().context(MultiChatClientHandler.class);
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            while (true) {
                String line = in.readLine();
                if (line == null) {
                    break;
                }
                if (line.equals('LIST')) {
                    String username = null;
                    ctx.writeAndFlush(line + '|' + username + '\n');
                } else {
                    ctx.writeAndFlush(line + '\n');
                }
            }
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        String host = 'localhost';
        int port = 8080;
        new MultiChatClient(host, port).run();
    }
}

MultiChatClientHandler

package org.example;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class MultiChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

MultiChatServerHandler

package org.example;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.concurrent.EventExecutorGroup;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class MultiChatServerHandler extends SimpleChannelInboundHandler<String> {
    private final ConcurrentHashMap<String, ChannelHandlerContext> userMap;
    private final EventExecutorGroup group;

    public MultiChatServerHandler(ConcurrentHashMap<String, ChannelHandlerContext> userMap, EventExecutorGroup group) {
        this.userMap = userMap;
        this.group = group;
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println('Client connected: ' + ctx.channel().remoteAddress());
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println('Client disconnected: ' + ctx.channel().remoteAddress());
        userMap.values().remove(ctx);
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        String[] tokens = msg.split('\|');
        String command = tokens[0];

        System.out.println('Received message from client: ' + msg);
        switch (command) {
            case 'LOGIN':
                handleLogin(ctx, tokens[1], tokens[2]);
                break;
            case 'LIST':
                handleList(ctx);
                break;
            case 'MSG':
                handleMessage(ctx, tokens[1], tokens[2]);
                break;
            case 'PRIVATE':
                handlePrivateMessage(ctx, tokens[1], tokens[2]);
                break;
            default:
                ctx.writeAndFlush('Invalid command: ' + command);
                break;
        }
    }

    private void handleLogin(ChannelHandlerContext ctx, String username, String password) {
        if (userMap.containsKey(username)) {
            ctx.writeAndFlush('User already logged in: ' + username);
        } else {
            userMap.put(username, ctx);
            ctx.writeAndFlush('Login successful: ' + username);
        }
    }

    private void handleList(ChannelHandlerContext ctx) {
        StringBuilder sb = new StringBuilder();
        sb.append('Available chat rooms:\n');
        for (Map.Entry<String, ChannelHandlerContext> entry : userMap.entrySet()) {
            sb.append(entry.getKey()).append('\n');
        }
        boolean username = false;
        if (userMap.containsKey(username)) {
            sb.append('Your information:\n');
            sb.append(username).append('\n');
        }
        ctx.writeAndFlush(sb.toString());
    }

    private void handleMessage(ChannelHandlerContext ctx, String roomName, String message) {
        StringBuilder sb = new StringBuilder();
        sb.append('[').append(ctx.channel().remoteAddress()).append('] ').append(message).append('\n');
        for (Map.Entry<String, ChannelHandlerContext> entry : userMap.entrySet()) {
            if (entry.getKey().equals(roomName)) {
                entry.getValue().writeAndFlush(sb.toString());
            }
        }
    }

    private void handlePrivateMessage(ChannelHandlerContext ctx, String recipient, String message) {
        StringBuilder sb = new StringBuilder();
        sb.append('[').append(ctx.channel().remoteAddress()).append('] (private) ').append(message).append('\n');
        if (userMap.containsKey(recipient)) {
            userMap.get(recipient).writeAndFlush(sb.toString());
        } else {
            ctx.writeAndFlush('User not found: ' + recipient);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

运行结果

这段代码的运行结果会根据具体的输入和交互情况而变化。例如，当客户端连接到服务器时，会打印出连接成功的消息；当客户端断开连接时，会打印出断开连接的消息；当客户端发送消息给服务器时，服务器会根据消息的指令进行相应的处理，并发送消息给指定的聊天室或用户。