本篇文章基于Netty做一个聊天室案例加强Netty的熟练度，案例的效果是服务端可以广播某客户端的消息给所有客户端。每个客户端监听键盘输入来获取消息，然后发送给服务端
服务端
服务端一样的需要创建BossGroup 和 WorkGroup , 然后使用ServerBootStrap 来配置Netty和启动Netty。
public class NettyGroupChatServer { public static void main(String[] args) { new NettyGroupChatServer().start(); } //监听 public void start(){ //循环组 NioEventLoopGroup bossGroup = new NioEventLoopGroup(); NioEventLoopGroup workGroup = new NioEventLoopGroup(); //启动引导 ServerBootstrap bootstrap = new ServerBootstrap(); //Netty配置 bootstrap.group(bossGroup,workGroup) .option(ChannelOption.SO_BACKLOG,32) .childOption(ChannelOption.SO_KEEPALIVE,true) .channel(NioServerSocketChannel.class) .childHandler(new ChannelInitializer() { @Override protected void initChannel(SocketChannel channel) throws Exception { //解码器 channel.pipeline().addLast("decoder", new StringDecoder()); //编码器 channel.pipeline().addLast("encoder",new StringEncoder()); //处理器 channel.pipeline().addLast("nettyGroupChatHandler",new NettyGroupChatServerHandler()); } }); try { //启动服务 ChannelFuture future = bootstrap.bind(new InetSocketAddress("127.0.0.1", 8888)).sync(); future.channel().closeFuture().sync(); } catch (InterruptedException e) { e.printStackTrace(); }finally { //关闭资源 bossGroup.shutdownGracefully(); workGroup.shutdownGracefully(); } } } 服务端处理器我们通过继承 SimpleChannelInboundHandler 入站Handler来处理消息。
其中提供了几个方法
- channelRead0 ()：读取消息
- handlerRemoved ()：客户端断开
- handlerAdded ()：客户端建立连接
- exceptionCaught ()：出现异常
具体代码如下
public class NettyGroupChatServerHandler extends SimpleChannelInboundHandler{ //把所有客户端的channel保存起来 private static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE); private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); @Override protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception { String message = dateFormat.format(new Date())+":%s:"+msg; //消息转发给所有的客户端 channels.forEach(channel -> { if(channel == ctx.channel()){ String sendMsg = String.format(message, "我"); channel.writeAndFlush(sendMsg); System.out.println(sendMsg); }else{ String sendMsg = String.format(message, ctx.channel().remoteAddress()); channel.writeAndFlush(sendMsg); System.out.println(sendMsg); } }); } //断开连接 , 把消息广播给其他客户端 @Override public void handlerRemoved(ChannelHandlerContext ctx) throws Exception { String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":断开连接"; channels.writeAndFlush(message); System.out.println(message); } //建立连接 @Override public void handlerAdded(ChannelHandlerContext ctx) throws Exception { String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":加入聊天室"; //自动把消息广播给其客户端 channels.writeAndFlush(message); //客户端加入组 channels.add(ctx.channel()); System.out.println(message); } //出现异常 @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ctx.channel().close(); } //客户端退出 @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":退出聊天室"; System.out.println(message); } //客户端出于活动 @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":上线啦"; System.out.println(message); } }
客户端
客户端需要创建一个循环事件组，然后通过BootStrap去启动,然后扫描键盘输入作为数据源来把信息发送给服务端
public class NettyGroupChatClient { public static void main(String[] args) { new NettyGroupChatClient().start(); } public void start(){ NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(eventLoopGroup) .channel(NioSocketChannel.class) .handler(new ChannelInitializer() { @Override protected void initChannel(SocketChannel channel) throws Exception { //解码器 channel.pipeline().addLast("decoder", new StringDecoder()); //编码器 channel.pipeline().addLast("encoder",new StringEncoder()); //处理器 channel.pipeline().addLast("nettyGroupChatClientHandler",new NettyGroupChatClientHandler()); } }); try { ChannelFuture future = bootstrap.connect(new InetSocketAddress("127.0.0.1", 8888)).sync(); //通道 Channel channel = future.channel(); //扫描键盘输入 Scanner scanner = new Scanner(System.in); while(scanner.hasNextLine()){ String message = scanner.nextLine(); //发送数据 channel.writeAndFlush(message); } } catch (InterruptedException e) { }finally { eventLoopGroup.shutdownGracefully(); } } } 对于处理器只需要接收服务端转发过来的消息即可
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