/**

 * 聊天室服务端

 */

public class ChatRoomServer {

    private final int port ;

    public ChatRoomServer(int port) {

        this.port = port;

    }

    public void start(){

        EventLoopGroup boss = new NioEventLoopGroup();

        EventLoopGroup worker = new NioEventLoopGroup();

        try{

            ServerBootstrap bootstrap = new ServerBootstrap();

            bootstrap.group(boss,worker)

                    .channel(NioServerSocketChannel.class)

                    .childHandler(new ChatServerInitialize())

                    .option(ChannelOption.SO_BACKLOG, 128)

                    .option(ChannelOption.SO_KEEPALIVE, true);

            ChannelFuture future = bootstrap.bind(port).sync();

            future.channel().closeFuture().sync();

        }catch (Exception e){

            e.printStackTrace();

        }finally {

            boss.shutdownGracefully();

            worker.shutdownGracefully();

        }

    }

    public static void main(String[] args) {

        new ChatRoomServer(9999).start();  //服务端监听本地的9999端口

    }

}

public class ChatServerInitialize extends ChannelInitializer<SocketChannel>{

    @Override

    protected void initChannel(SocketChannel channel) throws Exception {

        System.out.println("用户【"+channel.remoteAddress()+"】接入聊天室......");

        ChannelPipeline pipeline = channel.pipeline();

        pipeline.addLast("framer",new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));

        pipeline.addLast("decoder",new StringDecoder());

        pipeline.addLast("encoder",new StringEncoder());

        pipeline.addLast("handler",new ChatServerHandler());

    }

}

/**

 * 聊天服务器对各种情况的处理

 */

public class ChatServerHandler extends SimpleChannelInboundHandler<String> {

    public static final ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    /**

     * 当从服务端收到新的客户端连接时

     * 客户端的 Channel 存入 channels 列表中，并通知列表中的其他客户端 Channel

     */

    @Override

    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {

        Channel clientChannel = ctx.channel();

        channels.add(clientChannel);

        for (Channel ch : channels) {

            if (ch != clientChannel) {  //通知除了自己以外的其他用户

                ch.writeAndFlush("【提示】：用户【" + clientChannel.remoteAddress() + "】进入聊天室...\n");

            }

        }

    }

    /**

     * 每当从服务端收到客户端断开时

     * 客户端的 Channel 自动从 channels 列表中移除了，并通知列表中的其他客户端 Channel

     */

    @Override

    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {

        Channel clientChannel = ctx.channel();

        channels.remove(clientChannel);

        for (Channel ch : channels) {

            if (ch != clientChannel) {  //通知除了自己以外的其他用户

                ch.writeAndFlush("【提示】：用户【" + clientChannel.remoteAddress() + "】退出聊天室...\n");

            }

        }

    }

    /**

     * 接受到客户端发出的消息

     * 判断channel是否是

     */

    @Override

    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {

        Channel clientChannel = ctx.channel();

        for (Channel ch : channels) {

            if (ch != clientChannel) {

                ch.writeAndFlush("用户【" + clientChannel.remoteAddress() + "】说：" + msg + "\n");

            } else {

                ch.writeAndFlush("【我】说：" + msg + "\n");

            }

        }

    }

    /**

     * 服务端监听到客户端活动

     */

    @Override

    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        Channel clientChannel = ctx.channel();

        System.out.println("用户【"+clientChannel.remoteAddress()+"】在线中...");

    }

    /**

     * 服务端监听到客户端 不活动

     */

    @Override

    public void channelInactive(ChannelHandlerContext ctx) throws Exception {

        Channel clientChannel = ctx.channel();

        System.out.println("用户【 " +clientChannel.remoteAddress()+"】:离线了");

    }

}

/**

 * 聊天客户端

 */

public class ChatClient {

    private final String host;

    private final int port;

    public ChatClient(String host, int port) {

        this.host = host;

        this.port = port;

    }

    public void start() {

        EventLoopGroup worker = new NioEventLoopGroup();

        Bootstrap bootstrap = new Bootstrap();

        try{

            bootstrap.group(worker)

                    .channel(NioSocketChannel.class)

                    .handler(new ClientInitializer());

            Channel channel  = bootstrap.connect(host,port).sync().channel();

            //客户端从键盘输入数据

            BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

            while(true){

                channel.writeAndFlush(input.readLine()+"\n");

            }

        }catch (Exception e){

            e.printStackTrace();

        }finally {

            worker.shutdownGracefully();

        }

    }

    public static void main(String[] args) {

        new ChatClient("127.0.0.1",9999).start(); //连接服务器端

    }

}

public class ChatClientInitializer extends ChannelInitializer<SocketChannel>{

    @Override

    protected void initChannel(SocketChannel socketChannel) throws Exception {

        //当有客户端连接服务器时，netty会调用这个初始化器的 initChannel方法

        System.out.println("客户端开始初始化......");

        ChannelPipeline pipeline = socketChannel.pipeline();

        pipeline.addLast("framer",new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));

        pipeline.addLast("decoder",new StringDecoder());

        pipeline.addLast("encoder",new StringEncoder());

        pipeline.addLast("handler",new ChatClientHandler());

    }

}

public class ChatClientHandler extends SimpleChannelInboundHandler<String> {

    /**

     * 打印服务端发送过来的数据

     */

    @Override

    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {

        System.out.println(s);

    }

}