Netty小案例

标签：适配   public   override   读取   info   如图所示   extends   connect   syn   

Netty是基于主从Reactor模型的 BossGroup只关系Accpet(连接的建立) 维护selector  接收到Accpet事件后 获取到对应的SocketChannel 并封装成NIOSocketChannel并注册到Worker，进行维护，当Woker监听到selector 中通道发生感兴趣的事情 就由handler进行处理 （handler需要先添加进通道中）模型如图所示：

 NettyClient：

public class NettyClient {
    public static void main(String[] args) throws InterruptedException {
        //客户端需要一个事件循环组
        NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup();
        try{
        //创建客户端启动对象
        Bootstrap bootstrap = new Bootstrap();
        //设置相关参数
        bootstrap.group(nioEventLoopGroup)
                .channel(NioSocketChannel.class).
                handler(new ChannelInitializer() {
                    @Override
                    protected void initChannel(SocketChannel channel) throws Exception {
                channel.pipeline().addLast(new NettyClientHandler());
                    }
                });
        System.out.println("客户端准备好了");
        //启动客户端去连接服务器端
        ChannelFuture cf = bootstrap.connect("127.0.0.1", 8848).sync();
        cf.channel().closeFuture().sync();
        }finally {
            nioEventLoopGroup.shutdownGracefully();
        }
    }
}
ClentHandler:

public class NettyClientHandler extends ChannelInboundHandlerAdapter {
    //通道就绪触发该方法
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        super.channelActive(ctx);
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello，123", CharsetUtil.UTF_8));
    }
//当通道有读取事件时
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf= (ByteBuf) msg;
        System.out.println(byteBuf.toString(CharsetUtil.UTF_8));
        System.out.println(ctx.channel().remoteAddress());
    }
    @Override
    //处理异常 一般需要关闭通道
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.channel().close();
    }
}
Server:

public class NettyServer {
    public static void main(String[] args) throws InterruptedException {
        //创建BossGroup和WorkerGroup
        //bossGroup处理连接请求 workerGroup处理业务
        //底层都是无限循环
       EventLoopGroup boosGroup = new NioEventLoopGroup();
        EventLoopGroup workerGruop = new NioEventLoopGroup();
        try{
        //服务器端启动对象 配置参数
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap.group(boosGroup,workerGruop)//设置两个线程组
        .channel(NioServerSocketChannel.class)//设置通道类型
        .option(ChannelOption.SO_BACKLOG,128)//设置线程队列的连接个数
        .childOption(ChannelOption.SO_KEEPALIVE,true)//设置保持活动状态
        .childHandler(new ChannelInitializer() {
            //给pipeline设置处理器
            @Override
            protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new NettyServerHandler());
            }
        });//给workerGroup的EventLoop对应的管道设置处理器
        System.out.println("服务器准备好了");
        //绑定端口并启动服务器
        ChannelFuture channelFuture = serverBootstrap.bind(8848).sync();
           //对通道关闭进行监听
        channelFuture.channel().closeFuture().sync();
        }
        finally {
            boosGroup.shutdownGracefully();
            workerGruop.shutdownGracefully();
        }
    }
}
ServerHandler:

//自定义的handler需要实现netty规定的某个适配器 自定义的handler才能称为handler
public class NettyServerHandler extends ChannelInboundHandlerAdapter {
    //读取客户端发送的消息
    /*
    ChannelHandlerContext上下文对象 含有通道 管道  地址等
    Object msg 客户端发送的数据
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

ByteBuf byteBuf=(ByteBuf)msg;
        System.out.println(byteBuf.toString(CharsetUtil.UTF_8));
        System.out.println(ctx.channel().remoteAddress());
    }
    //数据读取完毕
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        //数据写入缓冲并刷新
        //数据需要编码并发送
     ctx.writeAndFlush(Unpooled.copiedBuffer("hello",CharsetUtil.UTF_8));
    }
    @Override
    //处理异常 一般需要关闭通道
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.channel().close();
    }
}

Netty小案例

标签：适配   public   override   读取   info   如图所示   extends   connect   syn   

原文地址：https://www.cnblogs.com/mc-74120/p/13342933.html