Netty学习心得 netty服务端和客户端的连接

最近一直在学习Java的NIO框架 Netty，主要学习资料是李林峰老师写的 Netty权威指南，这本书介绍的十分详细，我也还在学习之中。第一篇就先介绍一下Netty的服务端和客户端的例子吧

虽然书中的demo都是基于Netty5的，但现在Netty5好像被丢弃啦，官网连beta版都没有，所以我还是选择啦Netty4的版本来开发

服务端主要是接受客户端传来的数据，然后在serverHandler中进行业务处理

服务端代码

public class Server {

    public static void main(String[] args) {
        // 服务类
        ServerBootstrap b = new ServerBootstrap();

        // 创建boss和worker
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            // 设置循环线程组事例
            b.group(bossGroup, workerGroup);

            // 设置channel工厂
            b.channel(NioServerSocketChannel.class);

            // 设置管道
            b.childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new RequestDecoder());
                    ch.pipeline().addLast(new ResponseEncoder());
                    ch.pipeline().addLast(new ServerHandler());
                }
            });

            b.option(ChannelOption.SO_BACKLOG, 2048);// 链接缓冲池队列大小

            // 绑定端口
            b.bind(10111).sync();

            System.out.println("start!!!");

        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            //释放资源
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

服务端的消息处理代码

public class ServerHandler extends SimpleChannelInboundHandler<String> {

    /** * 消息处理 */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg)throws Exception {

        // 打印输出消息
        System.out.println("服务端接受的消息 : " + msg);
        // 返回客户端消息
        ctx.writeAndFlush("hello");
    }


    /** * 新客户端接入 */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelActive");
        super.channelActive(ctx);
    }

    /** * 客户端断开 */
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelInactive");
        super.channelInactive(ctx);
    }

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


}

客户端主要是向服务端发送数据，处理服务端返回的数据

客户端代码

public class Client {

    public static void main(String[] args) {
        //客户端服务类
        Bootstrap bootstrap = new Bootstrap();

        //worker
        EventLoopGroup worker = new NioEventLoopGroup();

        try {
            //设置线程池
            bootstrap.group(worker);

            //设置socket工厂、
            bootstrap.channel(NioSocketChannel.class);

            //设置管道
            bootstrap.handler(new ChannelInitializer<Channel>() {

                @Override
                protected void initChannel(Channel ch) throws Exception {
                    ch.pipeline().addLast(new StringDecoder());
                    ch.pipeline().addLast(new StringEncoder());
                    ch.pipeline().addLast(new ClientHandler());
                }
            });

            ChannelFuture connect = bootstrap.connect("127.0.0.1", 10111).sync();

            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
            while(true){
                System.out.println("请输入：");

                String msg = bufferedReader.readLine();
                connect.channel().writeAndFlush(msg);
            }

        } catch (Exception e) {
             e.printStackTrace();
        } finally{
            worker.shutdownGracefully();
        }
    }
}

客户端消息处理

public class ClientHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {  
        System.out.println("客户端接受的消息: " + msg);
    }

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

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelInactive ");
        super.channelInactive(ctx);
    }

}

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