服务端和客户端请求应答

1.Server

1.1 启动类

public class Server {
    public static void main(String[] args) throws Exception{
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();

        ServerBootstrap serverBootstrap = new ServerBootstrap();
        try {
            serverBootstrap.group(boss, worker)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ServerChannelInitializer());

            ChannelFuture future = serverBootstrap.bind(8888).sync();
            future.channel().closeFuture().sync();
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

1.2 ChannelInitializer

public class ServerChannelInitializer 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 ServerHandler());
    }
}

1.3 ServerHandler

public class ServerHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        Thread.sleep(1000);
        System.out.println(ctx.channel().remoteAddress() + ",获取到数据 " + msg);
        ctx.channel().writeAndFlush("from server" + UUID.randomUUID());
    }

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

2.Client

2.1 启动类

public class Client {

    public static void main(String[] args) throws Exception{
        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        try {
            bootstrap.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new ClientInitializer());

            ChannelFuture channelFuture = bootstrap.connect("localhost", 8888).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
}

2.2 ChannelInitializer

public class ClientInitializer 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 ClientHandler());
    }
}

2.3 ChannelHandler

public class ClientHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        Thread.sleep(1000);
        System.out.println(ctx.channel().remoteAddress() + "," + msg);
        ctx.channel().writeAndFlush("from client:" + LocalDateTime.now());
    }

// 这个不行
//    @Override
//    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
//        ctx.writeAndFlush("start");
//    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush("start");
    }

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