2、张龙netty学习 netty服务端和客户端简单实现

netty服务端和客户端简单实现

服务端：

public class MyServer {
    public static void main(String[] args)throws Exception {
        EventLoopGroup boosGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap().group(boosGroup,workGroup)
                    .channel(NioServerSocketChannel.class).childHandler(new MyServerInitializer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            boosGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }

    }
}

public class MyServerInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(
                new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyServerHandle());
    }
}

public class MyServerHandle extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(ctx.channel().remoteAddress()+","+msg);
        ctx.channel().writeAndFlush("from server :"+ UUID.randomUUID());
    }
    // 异常情况
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        // 如果出现异常连接关闭
        ctx.channel().closeFuture();
    }
}

客户端

public static void main(String[] args)throws Exception {
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .handler(new MyClientInitializer());
            ChannelFuture channelFuture = bootstrap.connect("localhost", 8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }

public class MyClientInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(
                new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyClientHandle());
    }
}

public class MyClientHandle extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(ctx.channel().remoteAddress());
        System.out.println("client output:"+msg);
        ctx.writeAndFlush("from client: "+ LocalDateTime.now());
    }

    // 监听连接建立事件  连接建立发送消息
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.channel().writeAndFlush("客户端发出消息");
    }

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