简介

UDP 是User Datagram Protocol的简称，中文名是用户数据报协议
UDP协议与TCP协议一样用于处理数据包，在OSI模型中，两者都位于传输层，处于IP协议的上一层
UDP有不提供数据包分组、组装和不能对数据包进行排序的缺点，也就是说，当报文发送之后，是无法得知其是否安全完整到达的
UDP用来支持那些需要在计算机之间传输数据的网络应用

实例demo

服务端实现

/**
 * udp服务端
 *
 * @author LionLi
 */
public class UdpServer {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group)
                    // 主线程处理
                    .channel(NioDatagramChannel.class)
                    // 广播
                    .option(ChannelOption.SO_BROADCAST, true)
                    // 设置读缓冲区为2M
                    .option(ChannelOption.SO_RCVBUF, 2048 * 1024)
                    // 设置写缓冲区为1M
                    .option(ChannelOption.SO_SNDBUF, 1024 * 1024)
                    .handler(new ChannelInitializer<NioDatagramChannel>() {
                        @Override
                        protected void initChannel(NioDatagramChannel ch) {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new NioEventLoopGroup(), new UdpServerHandler());
                        }
                    });
            ChannelFuture f = bootstrap.bind(8088).sync();
            System.out.println("服务器正在监听......");
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
}

服务端业务处理实现

/**
 * 服务端业务处理
 *
 * @author LionLi
 */
public class UdpServerHandler extends SimpleChannelInboundHandler<DatagramPacket> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket packet) {
        System.out.println("服务端接收到消息：" + packet.content().toString(StandardCharsets.UTF_8));
        // 向客户端发送消息
        ByteBuf byteBuf = Unpooled.copiedBuffer("已经接收到消息!".getBytes(StandardCharsets.UTF_8));
        ctx.writeAndFlush(new DatagramPacket(byteBuf, packet.sender()));
    }
}

客户端实现

/**
 * udp客户端
 *
 * @author LionLi
 */
public class UdpClient {
    public static void main(String[] args) {
    EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group)
                    .channel(NioDatagramChannel.class)
                    .handler(new ChannelInitializer<NioDatagramChannel>() {
                        @Override
                        protected void initChannel(NioDatagramChannel ch) {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new UdpClientHandler());
                        }
                    });
            Channel channel = bootstrap.bind(8089).sync().channel();
            InetSocketAddress address = new InetSocketAddress("localhost", 8088);
            ByteBuf byteBuf = Unpooled.copiedBuffer("你好服务器".getBytes(StandardCharsets.UTF_8));
            channel.writeAndFlush(new DatagramPacket(byteBuf, address)).sync();
            channel.closeFuture().await();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            group.shutdownGracefully();
        }
    }
}

客户端业务处理

/**
 * 客户端业务处理
 *
 * @author LionLi
 */
public class UdpClientHandler extends SimpleChannelInboundHandler<DatagramPacket> {
    //接受服务端发送的内容
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket packet) {
        System.out.println("客户端接收到消息：" + packet.content().toString(StandardCharsets.UTF_8));
        // 向客户端发送消息
        ByteBuf byteBuf = Unpooled.copiedBuffer("你好服务器".getBytes(StandardCharsets.UTF_8));
        ctx.writeAndFlush(new DatagramPacket(byteBuf, packet.sender()));
    }
}