初识Netty

public class NettyServer {

    public static void main(String[] args) throws Exception {
        //1. 创建一个线程组：接收客户端连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //2. 创建一个线程组：处理网络操作
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        //3. 创建服务器端启动助手来配置参数
        ServerBootstrap b = new ServerBootstrap();
        //4.设置两个线程组
        b.group(bossGroup, workerGroup)
                //5.使用NioServerSocketChannel作为服务器端通道的实现
                .channel(NioServerSocketChannel.class)
                //6.设置线程队列中等待连接的个数
                .option(ChannelOption.SO_BACKLOG, 128)
                //7.保持活动连接状态
                .childOption(ChannelOption.SO_KEEPALIVE, true)
                //9. 往Pipeline链中添加自定义的handler类
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    //8. 创建一个通道初始化对象
                    @Override
                    public void initChannel(SocketChannel sc) {
                        sc.pipeline().addLast(new NettyServerHandler());
                    }
                });
        System.out.println("......Server is ready......");
        //10. 绑定端口 bind方法是异步的  sync方法是同步阻塞的
        ChannelFuture cf = b.bind(9999).sync();
        System.out.println("......Server is starting......");

        //11. 关闭通道，关闭线程组
        cf.channel().closeFuture().sync();
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
    }
}

public class NettyServerHandler extends ChannelInboundHandlerAdapter {

    /**
     * 读取数据事件
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        System.out.println("Server:" + ctx);
        ByteBuf buf = (ByteBuf) msg;
        System.out.println("客户端发来的消息：" + buf.toString(CharsetUtil.UTF_8));
    }

    /**
     * 数据读取完毕事件
     */
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("就是没钱", CharsetUtil.UTF_8));
    }

    /**
     * 异常发生事件
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable t) {
        ctx.close();
    }

}

......Server is ready......
......Server is starting......
Server:ChannelHandlerContext(NettyServerHandler#0, [id: 0xd3d1c749, L:/127.0.0.1:9999 - R:/127.0.0.1:51856])
客户端发来的消息：老板，还钱吧

Process finished with exit code 130 (interrupted by signal 2: SIGINT)

public class NettyClient {

    public static void main(String[] args) throws Exception {

        //1. 创建一个线程组
        EventLoopGroup group = new NioEventLoopGroup();
        //2. 创建客户端的启动助手，完成相关配置
        Bootstrap b = new Bootstrap();
        //3. 设置线程组
        b.group(group)
                //4. 设置客户端通道的实现类
                .channel(NioSocketChannel.class)
                //5. 创建一个通道初始化对象
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) {
                        //6.往Pipeline链中添加自定义的handler
                        socketChannel.pipeline().addLast(new NettyClientHandler());
                    }
                });
        System.out.println("......Client is  ready......");

        //7.启动客户端去连接服务器端  connect方法是异步的   sync方法是同步阻塞的
        ChannelFuture cf = b.connect("127.0.0.1", 9999).sync();

        //8.关闭连接(异步非阻塞)
        cf.channel().closeFuture().sync();

    }
}

public class NettyClientHandler extends ChannelInboundHandlerAdapter {

    /**
     * 通道就绪事件
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        System.out.println("Client:" + ctx);
        ctx.writeAndFlush(Unpooled.copiedBuffer("老板，还钱吧", CharsetUtil.UTF_8));
    }

    /**
     * 读取数据事件
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf buf = (ByteBuf) msg;
        System.out.println("服务器端发来的消息：" + buf.toString(CharsetUtil.UTF_8));
    }

}

......Client is  ready......
Client:ChannelHandlerContext(NettyClientHandler#0, [id: 0xc181fc12, L:/127.0.0.1:51856 - R:/127.0.0.1:9999])
服务器端发来的消息：就是没钱

Process finished with exit code 130 (interrupted by signal 2: SIGINT)