Netty学习（五）：Netty实现UDP的Server端

@SpringBootApplication
public class UdpListenerApplication implements CommandLineRunner {
    @Value("${netty.port}")
    private int port;

    @Value("${netty.url}")
    private String url;

    @Autowired
    private BootNettyUdpServer bootNettyUdpServer;

    @Override
    public void run(String... args) throws Exception {
        
        InetSocketAddress address = new InetSocketAddress(url, port);
        System.out.println("服务端启动成功：" + url + ":" + port);
        bootNettyUdpServer.start(address);

    }

    public static void main(String[] args) {
        SpringApplication.run(UdpListenerApplication.class, args);
        System.out.println("UdpListenerApplication启动成功......");
    }
}

@Service
public class BootNettyUdpServer {
    //logger
    private static final Logger log = LoggerFactory.getLogger(BootNettyUdpServer.class);

    @Autowired
    BootNettyUdpSimpleChannelInboundHandler bootNettyUdpSimpleChannelInboundHandler;

    
    public void start(InetSocketAddress address) {

        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();//
            b.group(workerGroup).channel(NioDatagramChannel.class)//设置UDP通道
                   // .handler(new BootNettyUdpSimpleChannelInboundHandler())//初始化处理器
                    .handler(bootNettyUdpSimpleChannelInboundHandler)//初始化处理器
                    .option(ChannelOption.SO_BROADCAST, true)// 支持广播
                    .option(ChannelOption.SO_RCVBUF, 1024 * 1024)// 设置UDP读缓冲区为1M
                    .option(ChannelOption.SO_SNDBUF, 1024 * 1024);// 设置UDP写缓冲区为1M

            System.out.println("[UDP 启动了]");

            // 绑定端口，开始接收进来的连接
            ChannelFuture f = b.bind(address).sync();
            //让线程进入wait状态，也就是main线程暂时不会执行到finally里面，nettyserver也持续运行，如果监听到关闭事件，可以优雅的关闭通道和nettyserver
            f.channel().closeFuture().sync();
        } catch (Exception e) {
            // TODO: handle exception
            System.out.println("Exception"+e.toString());
            workerGroup.shutdownGracefully();
        }
    }
}

@Component
public class BootNettyUdpSimpleChannelInboundHandler extends SimpleChannelInboundHandler {
    private static final Charset CHARSET = Charset.forName("GBK");
    private static Logger logger = LoggerFactory.getLogger(BootNettyUdpSimpleChannelInboundHandler.class);

    @Autowired
    ParserManager parserManager;


    @Override
    protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket datagramPacket) throws Exception {
        try {
            logger.info("服务器接收到了数据");
            ByteBuf byteBuf = datagramPacket.copy().content();
            logger.info("接收到的数据,hexDump：{}", ByteBufUtil.hexDump(byteBuf));

            frame frame = new frame();

            int len = getframeLength(byteBuf, frame);
            logger.info("帧长度为", len);

            if (len == 0) {
                logger.info("帧长度为", 0);
                return;
            } else if (len < 0) {
                logger.info("帧长度小于0，无效帧");
                // may be not a valid frame
                logger.error("recv a invalid frame, peer ip is: {}, close channel: {}, recv buffer: {}", ctx.channel().remoteAddress(), ctx.channel(), ByteBufUtil
                        .hexDump(byteBuf));

                byteBuf.skipBytes(byteBuf.readableBytes());
                return;
//                ctx.close();
            } else {
                if (!ctx.channel().isActive()) {
                    logger.info("channel is not active");
                }
                if (len > 1024) {
                    logger.error("frame len exceed limit len 1024, close it");
                    byteBuf.skipBytes(byteBuf.readableBytes());
//                    ctx.close();
                    return;
                }
                frame.setframeLength(len);

                frame.setInsertTime(DateUtils.currentDate());

                frame.setCtx(ctx);

                frame.setDatagramPacket(datagramPacket);
                byte[] body = ByteBufUtil.getBytes(byteBuf, byteBuf.readerIndex() + 4, len - 6);
                frame.setOrigin(body);
                frame.setEnder(byteBuf.getUnsignedShort(byteBuf.readerIndex() + (len - 2)));

                if (frame != null) {
                    parserManager.parser(frame);
                    logger.info("frame is {}", frame);
                } else {
                    byteBuf.release();
                    logger.warn("newRequestframe return a null frame, close channel");
                    ctx.close();
                }
                byteBuf.skipBytes(len);
            }

            //收到udp消息后，可通过此方式原路返回的方式返回消息，例如返回时间戳
//            ctx.writeAndFlush(new DatagramPacket(Unpooled.copiedBuffer("receice data", CharsetUtil.UTF_8),
//                    datagramPacket.sender()));
        } catch (Exception e) {
            logger.error("BootNettyUdpSimpleChannelInboundHandler.channelRead0发生异常", e);
        }
    }