Netty提供非同步的、事件驅動的網路應用程式框架和工具，用以快速開發高效能、高可靠性的網路伺服器和客戶端程式，阿里騰訊都有用到，這裡是個簡單的伺服器和客戶端的例子

程式碼目錄

服務端 NettyServerBootstrap類 NettyServerHandler類

客戶端NettyClient類 NettyClientHandler類

服務端

NettyServerBootstrap 類，建立服務端

public class NettyServerBootstrap {
    private int port;
    public NettyServerBootstrap
 
(int port) {
        this.port = port;
        bind();
    }
    private void bind() {
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(boss, worker);
            bootstrap.channel(NioServerSocketChannel.class);
            bootstrap.option(ChannelOption.SO_BACKLOG, 1024
 
); 
            bootstrap.option(ChannelOption.TCP_NODELAY, true); 
            bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true); 
            bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws
 
 Exception {
                    ChannelPipeline p = socketChannel.pipeline();
                    p.addLast(new NettyServerHandler());
                }
            });
            ChannelFuture f = bootstrap.bind(port).sync();
            if (f.isSuccess()) {
                Log.logD("啟動Netty服務成功，埠號：" + this.port);
            }
            // 關閉連線
            f.channel().closeFuture().sync();

        } catch (Exception e) {
            Log.logE("啟動Netty服務異常，異常資訊：" + e.getMessage());
            e.printStackTrace();
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        NettyServerBootstrap server = new NettyServerBootstrap(6666);
    }

}

服務端處理類NettyServerHandler

public class NettyServerHandler extends ChannelHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // TODO Auto-generated method stub
        //傳送資訊
        ctx.writeAndFlush(getSendByteBuf("伺服器-->客戶端 你好"));
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        //收到訊息
        ByteBuf buf = (ByteBuf) msg;// 獲取客戶端傳來的Msg
        String recieved = getMessage(buf);
        System.out.println("------收到資訊------"+recieved );   
    }

    /*
     * 從ByteBuf中獲取資訊 使用UTF-8編碼返回
     */
    private String getMessage(ByteBuf buf) {
        byte[] con = new byte[buf.readableBytes()];
        buf.readBytes(con);
        try {
            return new String(con, utils.Constant.UTF8);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return null;
        }
    }

    /*
     * 將Sting轉化為UTF-8編碼的位元組
     */
    private ByteBuf getSendByteBuf(String message) throws UnsupportedEncodingException {
        byte[] req = message.getBytes("UTF-8");
        ByteBuf pingMessage = Unpooled.buffer();
        pingMessage.writeBytes(req);
        return pingMessage;
    }
}

客戶端

NettyClient類

public class NettyClient {
    private int port;
    private String host;
    private SocketChannel socketChannel;

    public NettyClient(int port, String host) throws InterruptedException {
        this.port = port;
        this.host = host;
        start();
    }

    private void start() throws InterruptedException {
           EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
            bootstrap.group(eventLoopGroup);
            bootstrap.remoteAddress(host, port);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new NettyClientHandler());
                    socketChannel.pipeline().addLast(new HeartLinkHandler());
                }
            });
            ChannelFuture future = bootstrap.connect(host, port).sync();
            if (future.isSuccess()) {
                socketChannel = (SocketChannel) future.channel();
                System.out.println("------connect server success------");
            }
            future.channel().closeFuture().sync();
        } finally {
            eventLoopGroup.shutdownGracefully();    
        }
    }

    public static void main(String[] args) throws InterruptedException {
        NettyClient client = new NettyClient(6666, "localhost");
    }
}

客戶端處理類NettyClientHandler

public class NettyClientHandler extends ChannelHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // TODO Auto-generated method stub
        //傳送資訊
        ctx.writeAndFlush(getSendByteBuf("客戶端-->服務端 你好"));


    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        // TODO Auto-generated method stub
        ByteBuf buf = (ByteBuf) msg;// 獲取服務端傳來的Msg
        String recieved = getMessage(buf);
        System.out.println("------收到資訊------"+recieved ); 
     }

     /*
     * 將位元組UTF-8編碼返回字串
     */
    private String getMessage(ByteBuf buf) {
        byte[] con = new byte[buf.readableBytes()];
        buf.readBytes(con);
        try {
            return new String(con, utils.Constant.UTF8);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return null;
        }
    }

    /*
     * 將Sting轉化為UTF-8編碼的位元組
     */
    private ByteBuf getSendByteBuf(String message) throws UnsupportedEncodingException {
        byte[] req = message.getBytes("UTF-8");
        ByteBuf pingMessage = Unpooled.buffer();
        pingMessage.writeBytes(req);
        return pingMessage;
    }
}

然後先執行服務端，再執行客戶端，就可以看到列印的資訊了！！！是不是很簡單