【Java高级工程师蜕变之路】043 Netty高级进阶之基于Netty的群聊天室案例
本文通过实战演练，学习了如何使用Netty开发一个群聊天室。
Netty高级进阶之基于Netty的群聊天室案例
案例要求
- 编写一个 Netty 群聊系统，实现服务器端和客户端之间的数据简单通讯
- 实现多人群聊
- 服务器端:可以监测用户上线，离线，并实现消息转发功能
- 客户端:可以发送消息给其它所有用户，同时可以接受其它用户发送的消息
聊天室服务端编写
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服务端
/** * 聊天室服务端 * * @name: NettyChatServer * @author: terwer * @date: 2022-04-27 22:23 **/ public class NettyChatServer { private int port; public NettyChatServer(int port) { this.port = port; } public void run() throws InterruptedException { NioEventLoopGroup bossGroup = null; NioEventLoopGroup workerGroup = null; try { // 1. 创建bossGroup线程组: 处理网络事件--连接事件，默认是2*处理器线程数目 bossGroup = new NioEventLoopGroup(1); // 2. 创建workerGroup线程组: 处理网络事件--读写事件,默认是2*处理器线程数目 workerGroup = new NioEventLoopGroup(); // 3. 创建服务端启动助手 ServerBootstrap serverBootstrap = new ServerBootstrap(); // 4. 设置bossGroup线程组和workerGroup线程组 serverBootstrap.group(bossGroup, workerGroup) .channel(NioServerSocketChannel.class) .option(ChannelOption.SO_BACKLOG, 128) // 5. 设置服务端通道实现为NIO .childOption(ChannelOption.SO_KEEPALIVE, Boolean.TRUE) // 6. 参数设置，设置活跃状态，child是设置workerGroup .childHandler(new ChannelInitializer<SocketChannel>() { // 7. 创建一个通道初始化对象 @Override protected void initChannel(SocketChannel ch) throws Exception { // 8. 向pipeline中添加自定义业务处理handler // 添加编码器 ch.pipeline().addLast(new StringDecoder()); ch.pipeline().addLast(new StringEncoder()); // 自定义处理类 ch.pipeline().addLast(new NettyChatServerHandler()); } }); // 9. 启动服务端并绑定端口,同时将异步改为同步 ChannelFuture channelFuture = serverBootstrap.bind(port).sync(); System.out.println("群聊天室服务器启动成功"); channelFuture.addListener(new ChannelFutureListener() { @Override public void operationComplete(ChannelFuture future) throws Exception { if (future.isSuccess()) { System.out.println("端口绑定成功!"); } else { System.out.println("端口绑定失败!"); } } }); // 10. 关闭通道和关闭连接池(不是真正关闭，只是设置为关闭状态) channelFuture.channel().closeFuture().sync(); } finally { bossGroup.shutdownGracefully(); workerGroup.shutdownGracefully(); } } public static void main(String[] args) throws InterruptedException { new NettyChatServer(9998).run(); } } -
服务端业务处理类
/** * Netty聊天室业务处理类 * * @name: NettyChatServerHandler * @author: terwer * @date: 2022-04-27 22:31 **/ public class NettyChatServerHandler extends SimpleChannelInboundHandler<String> { public static List<Channel> channelList = new ArrayList<>(); /** * 通道就绪事件 * * @param ctx * @throws Exception */ @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { Channel channel = ctx.channel(); // 有客户端连接时，将通道放入集合 channelList.add(channel); System.out.println("【服务端】：" + channel.remoteAddress().toString().substring(1) + "上 线。"); } /** * 通道未就绪 * * @param ctx * @throws Exception */ @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { // channel下线 Channel channel = ctx.channel(); // 客户端连接端口，移除连接 channelList.remove(channel); System.out.println("【" + channel.remoteAddress().toString().substring(1) + "】下线。"); } /** * 通道读取事件 * * @param ctx * @param msg * @throws Exception */ @Override protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception { // 当前发送消息的通道 Channel channel = ctx.channel(); for (Channel channel1 : channelList) { // 排除自身通道 if (channel != channel1) { channel1.writeAndFlush("【" + channel.remoteAddress().toString().substring(1) + "】说：" + msg); } } } /** * 异常处理事件 * * @param ctx * @param cause * @throws Exception */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); Channel channel = ctx.channel(); System.out.println("【" + channel.remoteAddress().toString().substring(1) + "】发送异常。"); // 移除 channelList.remove(channel); } }
聊天室客户端编写
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聊天室客户端
/** * 聊天室客户端 * * @name: NettyChatClient * @author: terwer * @date: 2022-04-27 23:41 **/ public class NettyChatClient { private String ip; private int port; public NettyChatClient(String ip, int port) { this.ip = ip; this.port = port; } public void run() throws InterruptedException { NioEventLoopGroup group = null; try { // 1. 创建线程组 group = new NioEventLoopGroup(); // 2. 创建客户端启动助手 Bootstrap bootstrap = new Bootstrap(); // 3. 设置线程组 bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ChannelInitializer<SocketChannel>() { // 4. 设置客户端通道实现为NIO @Override protected void initChannel(SocketChannel ch) throws Exception { // 5. 创建一个通道初始化对象 // 6. 向pipeline中添加自定义业务处理handler //添加编解码器 ch.pipeline().addLast(new StringDecoder()); ch.pipeline().addLast(new StringEncoder()); // 添加客户端处理类 ch.pipeline().addLast(new NettyChatClientHandler()); } }); // 7. 启动客户端,等待连接服务端,同时将异步改为同步 ChannelFuture channelFuture = bootstrap.connect(ip, port).sync(); Channel channel = channelFuture.channel(); System.out.println("--------" + channel.localAddress().toString().substring(1) + "--------"); Scanner scanner = new Scanner(System.in); while (scanner.hasNextLine()) { String nextLine = scanner.nextLine(); // 向服务端发送消息 channel.writeAndFlush(nextLine); } // 8. 关闭通道和关闭连接池 channelFuture.channel().closeFuture().sync(); } finally { group.shutdownGracefully(); } } public static void main(String[] args) throws InterruptedException { new NettyChatClient("127.0.0.1", 9998).run(); } } -
客户端业务处理类
/** * 聊天室客户端业务处理类 * * @name: NettyChatClientHandler * @author: terwer * @date: 2022-04-27 23:45 **/ public class NettyChatClientHandler extends SimpleChannelInboundHandler<String> { /** * 通道读取事件 * * @param ctx * @param msg * @throws Exception */ @Override protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception { System.out.println(msg); } }
运行效果
