netty 入门案例hello world

1.依赖的jar包

     <dependency>
            <groupId>io.nettygroupId>
            <artifactId>netty-allartifactId>
            <version>4.1.8.Finalversion>
       dependency>

2. 服务端代码

public class NettyServer {

    public void start(int port) throws Exception
    {
        ServerBootstrap strap = new ServerBootstrap();
        EventLoopGroup boosGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            strap.group(boosGroup, workerGroup).
                    channel(NioServerSocketChannel.class).
                    option(ChannelOption.SO_BACKLOG, 1024).
                    childHandler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new NettyServerHandler());
                        }
                    });
            ChannelFuture future=strap.bind(port).sync();
            future.channel().closeFuture().sync();
        }finally {
            boosGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }

    public static void main(String[] args) throws Exception {
        System.out.println("start server");
        new NettyServer().start(8000);
    }
}

NettyServerHandler

public class NettyServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buf=(ByteBuf)msg;
        byte [] data=new byte[buf.readableBytes()];
        buf.readBytes(data);
        System.out.println(new String(data));
        String responseMsg="收到"+System.getProperty("line.separator");
        ByteBuf sendMsg= Unpooled.copiedBuffer(responseMsg.getBytes());
        ctx.writeAndFlush(sendMsg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        super.channelReadComplete(ctx);
    }

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

启动服务后，可以使用telnet 127.0.0.1 8000 来测试

3.客户端代码

public class NettyClient {
    public void connect(int port,String host) throws Exception
    {
        EventLoopGroup eventLoopGroup=new NioEventLoopGroup();
        Bootstrap bootstrap=new Bootstrap();
        try {

            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new NettyClientHandler());
                        }
                    });
            ChannelFuture future = bootstrap.connect(host, port).sync();
            future.channel().closeFuture().sync();
        }finally {
            eventLoopGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception{
        new NettyClient().connect(8000,"127.0.0.1");
    }
}

NettyClientHandler

public class NettyClientHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ByteBuf buf = Unpooled.copiedBuffer("hello world".getBytes());
        ctx.writeAndFlush(buf);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buf=(ByteBuf)msg;
        byte[] data=new byte[buf.readableBytes()];
        buf.readBytes(data);
        System.out.print(new String(data));
    }

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