springboot+netty编写一个群聊

当然可以！下面是一个使用Spring Boot和Netty编写的简单群聊示例：

1. 首先，创建一个Spring Boot项目，并添加Netty和Spring Boot的依赖。

2. 创建一个Netty服务器类，用于处理客户端的连接和消息发送：

@Component
public class ChatServer {

    private static final int PORT = 8080;

    private final ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    @PostConstruct
    public void start() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChatServerInitializer(channelGroup));

            Channel channel = bootstrap.bind(PORT).sync().channel();
            channel.closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

3. 创建一个Netty的ChannelInitializer类，用于配置ChannelPipeline：

public class ChatServerInitializer extends ChannelInitializer<SocketChannel> {

    private final ChannelGroup channelGroup;

    public ChatServerInitializer(ChannelGroup channelGroup) {
        this.channelGroup = channelGroup;
    }

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder());
        pipeline.addLast(new StringEncoder());

        pipeline.addLast(new ChatServerHandler(channelGroup));
    }
}

4. 创建一个Netty的ChannelInboundHandlerAdapter类，用于处理接收到的消息并广播给所有连接的客户端：

public class ChatServerHandler extends ChannelInboundHandlerAdapter {

    private final ChannelGroup channelGroup;

    public ChatServerHandler(ChannelGroup channelGroup) {
        this.channelGroup = channelGroup;
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();

        // 广播通知其他客户端有新用户加入
        channelGroup.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 加入\n");

        channelGroup.add(incoming);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel outgoing = ctx.channel();

        // 广播通知其他客户端有用户离开
        channelGroup.writeAndFlush("[SERVER] - " + outgoing.remoteAddress() + " 离开\n");

        channelGroup.remove(outgoing);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("Client: " + incoming.remoteAddress() + " 上线");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("Client: " + incoming.remoteAddress() + " 掉线");
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("Client: " + incoming.remoteAddress() + " 发送消息：" + msg);

        // 广播消息给所有连接的客户端
        channelGroup.writeAndFlush("[" + incoming.remoteAddress() + "]：" + msg + "\n");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("Client: " + incoming.remoteAddress() + " 异常");
        cause.printStackTrace();
        ctx.close();
    }
}

5. 配置Spring Boot启动类：

@SpringBootApplication
public class ChatApplication {

    public static void main(String[] args) {
        SpringApplication.run(ChatApplication.class, args);
    }

}

6. 运行Spring Boot应用程序，然后使用Telnet或其他工具连接到服务器的IP地址和端口号（默认为8080）。多个客户端连接到服务器后，发送的消息将被广播给所有连接的客户端。

这只是一个简单的群聊示例，你可以根据实际需求进行扩展和优化。希望对你有所帮助！