庆幸的是借助getty良好的设计模式，getty udp的使用方式与tcp差别不大。

唯一的区别就是需要指定socketChannel为UDP。默认不指定是TCP

需要指定UDP的消息编解码器

                //对于UDP而言，只有DatagramPacketEncoder、DatagramPacketDecoder两个处理器是有效的
                //原因在于UDP本身不存在连接，因而其他处理器即使配置了也是没有效果的
                defaultChannelPipeline.addLast(new DatagramPacketEncoder());
                defaultChannelPipeline.addLast(new DatagramPacketDecoder());

        //服务器端
        AioServerStarter server = new AioServerStarter(8888);
        //唯一的区别就是需要指定socketChannel为UDP。默认不指定是TCP
        server.socketChannel(SocketChannel.UDP).channelInitializer(new ChannelInitializer() {
            @Override
            public void initChannel(AioChannel channel) throws Exception {
                //获取责任链对象
                DefaultChannelPipeline defaultChannelPipeline = channel.getDefaultChannelPipeline();
                //对于UDP而言，只有DatagramPacketEncoder、DatagramPacketDecoder两个处理器是有效的
                //原因在于UDP本身不存在连接，因而其他处理器即使配置了也是没有效果的
                defaultChannelPipeline.addLast(new DatagramPacketEncoder());
                defaultChannelPipeline.addLast(new DatagramPacketDecoder());
                //添加自定义的简单消息处理器
                defaultChannelPipeline.addLast(new SimpleHandler());
            }
}).start();
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        //客户端
        AioClientConfig aioConfig = new AioClientConfig();
        //Host与port无需指定也没有关系，指定了也没有效果
        aioConfig.setHost("127.0.0.1");
        aioConfig.setPort(port);
        aioConfig.setClientChunkSize(512 * 1024 * 1024);
        aioConfig.setBufferWriterQueueSize(2 * 1024 * 1024);
        AioClientStarter client = new AioClientStarter(aioConfig);
        client.socketChannel(SocketChannel.UDP).channelInitializer(new ChannelInitializer() {
            @Override
            public void initChannel(AioChannel channel) throws Exception {
                //责任链
                DefaultChannelPipeline defaultChannelPipeline = channel.getDefaultChannelPipeline();
                defaultChannelPipeline.addLast(new DatagramPacketEncoder());
                defaultChannelPipeline.addLast(new DatagramPacketDecoder());
                //定义消息解码器
                defaultChannelPipeline.addLast(new SimpleHandler());
            }
        });
        try {
            client.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
//发送个消息给服务器
Thread.sleep(2000);
AioChannel aioChannel = client.getAioChannel();
String s = "hello getty";
byte[] msgBody = s.getBytes("utf-8");
//UDP消息发送的是DatagramPacket 发送的目标服务器在DatagramPacket 中指定
DatagramPacket datagramPacket = new DatagramPacket(msgBody, msgBody.length, new InetSocketAddress("127.0.0.1", 8888));
aioChannel.writeAndFlush(datagramPacket);

SimpleHandler的类型指定为 > DatagramPacket

public class SimpleHandler extends SimpleChannelInboundHandler<DatagramPacket> {
    @Override
    public void channelAdded(AioChannel aioChannel) {
        System.out.println("连接成功");
    }
    @Override
    public void channelClosed(AioChannel aioChannel) {
        System.out.println("连接关闭了");
    }
    @Override
    public void channelRead0(AioChannel aioChannel, DatagramPacket datagramPacket) {
        System.out.println("读取消息了:" + new String(datagramPacket.getData()));
        System.out.println("客户端地址:" + datagramPacket.getAddress().getHostName() + ":" + datagramPacket.getPort());
    }
    @Override
    public void exceptionCaught(AioChannel aioChannel, Throwable cause, PipelineDirection pipelineDirection) {
        System.out.println("出错了");
    }
}