使用Netty框架实现一个简单的CS结构的网络程序处理tcp半包问题粘包、拆包运行结果改成客户端输出ClientactiveClientreceivedHelloHelloNettyfromServer服务器端输出：Server started

客户端代码：

public class Client {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup group = new NioEventLoopGroup();

        try {
            Bootstrap bootstrap = new Bootstrap()
                    .group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new StringDecoder());
                            pipeline.addLast(new StringEncoder());
                            pipeline.addLast(new ClientHandler());
                        }
                    });

            ChannelFuture future = bootstrap.connect("localhost", 8888).sync();
            System.out.println("Client active...");

            future.channel().writeAndFlush("Hello,");

            TimeUnit.SECONDS.sleep(1);

            future.channel().writeAndFlush("Hello,");

            TimeUnit.SECONDS.sleep(1);

            future.channel().writeAndFlush("Netty,");

            TimeUnit.SECONDS.sleep(1);

            future.channel().writeAndFlush("fromClient.");

            future.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
}

客户端处理器代码：

public class ClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println("Client received: " + msg);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("Client active...");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

服务器端代码：

public class Server {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap bootstrap = new ServerBootstrap()
                    .group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new StringDecoder());
                            pipeline.addLast(new StringEncoder());
                            pipeline.addLast(new ServerHandler());
                        }
                    });

            ChannelFuture future = bootstrap.bind(8888).sync();
            System.out.println("Server started...");

            future.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

服务器端处理器代码：

public class ServerHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println("Server received: " + msg);
        ctx.channel().writeAndFlush("Hello," + msg);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

运行结果：

Client active...
Client received: Hello,Hello,Netty,fromServer.
``