用netty实现聊天

小灰灰 2023-10-10 17:55 20阅读 0赞

1.引入netty依赖

<dependencies>
    <dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>4.1.92.Final</version>
    </dependency>
    </dependencies>

2.准备一个服务端ChatServer和一个服务端处理器ChatServerHandler和若干个客户端ChatClient(有几个用户设置几个)和一个客户端处理器ChatClientHandler

服务端
    public class ChatServer {
        public static void main(String[] args) {
            // 新建两个事件循环组,bossGroup 用于监听客户端的连接请求，将连接请求发送给 workerGroup 用于处理客户端连接的数据读写
            NioEventLoopGroup bossGroup = new NioEventLoopGroup();
            NioEventLoopGroup workGroup = new NioEventLoopGroup();
    
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workGroup);
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.childHandler(new ChannelInitializer<NioSocketChannel>() {
                @Override
                protected void initChannel(NioSocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new StringEncoder(CharsetUtil.UTF_8));
                    ch.pipeline().addLast(new StringDecoder(CharsetUtil.UTF_8));
                    ch.pipeline().addLast(new ChatServerHandler());
                }
            });
            // 服务端绑定9000端口
            serverBootstrap.bind(9000);
        }
    
        public void test(){
            NioEventLoopGroup bossGroup = new NioEventLoopGroup();
            NioEventLoopGroup workGroup = new NioEventLoopGroup();
    
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup);
    
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.childHandler(new ChannelInitializer<NioSocketChannel>() {
                @Override
                protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
                    nioSocketChannel.pipeline().addLast(new StringEncoder(CharsetUtil.UTF_8));
                    nioSocketChannel.pipeline().addLast(new StringDecoder(CharsetUtil.UTF_8));
                    nioSocketChannel.pipeline().addLast(new ChatServerHandler());
                }
            });
    
            serverBootstrap.bind(9001);
        }
    }

服务端处理器

public class ChatServerHandler extends ChannelInboundHandlerAdapter {
    
        // 创建一个list集合存储连接上的所有客户端channel
        private static List<Channel> channels = new ArrayList<>();
    
        // 当有客户端连接上服务端,底层会调用此方法，执行此方法的逻辑
        // 这里大概的处理逻辑是:先添加新客户端channel到集合中，然后循环遍历list集合
        // 然后根据不同的channel发送不同的系统消息
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            Channel channel = ctx.channel();
            channels.add(channel);
            channels.forEach(ch -> {
                if (ch == channel) {
                    channel.writeAndFlush("恭喜您，上线成功");
                } else {
                    ch.writeAndFlush("系统消息:[" + ch.remoteAddress() + "]客户端已上线");
                }
            });
            System.out.println("客户端[" + channel.remoteAddress() + "]请求连接");
        }
    
        // 当有客户端连断开连接,底层会调用此方法，执行此方法的逻辑
        // 这里大概的处理逻辑是:然后循环遍历list集合,找到已断开连接的channel并删除
        // 向集合内的channel发送系统消息
        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            Channel channel = ctx.channel();
            Iterator<Channel> iterator = channels.iterator();
            while (iterator.hasNext()) {
                Channel ch = iterator.next();
                if (ch == channel) {
                    iterator.remove();
                }
                ch.writeAndFlush("系统消息:[" + channel.remoteAddress() + "]客户端已下线");
            }
            System.out.println("客户端[" + channel.remoteAddress() + "]断开连接");
        }
    
        // 当有客户端发送消息到服务端,底层会调用此方法，执行此方法的逻辑
        // 这里大概的处理逻辑是:循环遍历向集合中的channel(除发送消息的客户端)发送消息
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            Channel channel = ctx.channel();
            SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date = new Date(System.currentTimeMillis());
            String now = formatter.format(date);
            System.out.println(now+"收到用户[" + channel.remoteAddress() + "]发来的消息:" + msg.toString());
    
            channels.forEach(ch -> {
                if (ch != channel) {
                    ch.writeAndFlush("消息时间:" + now + " 用户[" + channel.remoteAddress() + "]说:" + msg.toString());
                }
            });
        }
    
    
        //异常触发
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            cause.printStackTrace();
            ctx.close();
        }
    }

客户端

public class ChatClient {
        public static void main(String[] args) throws InterruptedException {
            NioEventLoopGroup workGroup = new NioEventLoopGroup();
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(workGroup);
            bootstrap.channel(NioSocketChannel.class);
            // 设置处理器
            bootstrap.handler(new ChannelInitializer<NioSocketChannel>() {
                @Override
                protected void initChannel(NioSocketChannel ch) throws Exception {
                    // 将字符串编解码器及客户端处理器添加到pipeline中
                    ch.pipeline().addLast(new StringDecoder(CharsetUtil.UTF_8));
                    ch.pipeline().addLast(new StringEncoder(CharsetUtil.UTF_8));
                    ch.pipeline().addLast(new ChatClientHandler());
                }
            });
            // 连接服务端
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 9000);
            channelFuture.sync();
            // 获取客户端输入的内容，并发送至服务端(因为添加了字符串编解码器，所以此处可以直接发送字符串)
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()) {
                channelFuture.channel().writeAndFlush(scanner.nextLine());
            }
        }
    }

客户端处理器

public class ChatClientHandler extends ChannelInboundHandlerAdapter {
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            System.out.println(msg.toString());
        }
    
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            cause.printStackTrace();
            ctx.close();
        }
    }

如果需要多个客户端用户,将客户端多复制几个就可以了.

启动时先启动服务端再启动客户端

![e30bc46d5c3d4613bfce6915749c47bc.png][]

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[e30bc46d5c3d4613bfce6915749c47bc.png]: https://img-blog.csdnimg.cn/e30bc46d5c3d4613bfce6915749c47bc.png
[1b076599e1fb4e1b9e42b196e3d3a121.png]: https://img-blog.csdnimg.cn/1b076599e1fb4e1b9e42b196e3d3a121.png
[33a60beee87541c2ae4904eae4bd39b9.png]: https://img-blog.csdnimg.cn/33a60beee87541c2ae4904eae4bd39b9.png