Springboot中用 Netty 开启UDP服务方式

        
       <!--springboot version 我用的是2.1.3.RELEASE-->
		 <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>
       
       <!--web模块的启动器 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- netty依赖 springboot2.x自动导入版本 -->
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
        </dependency>
        
		<!-- 这里我用到了@slf4j 所以引入这个jar -->
      <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

package com.demo.udpdemo.UDPServer;
import com.demo.udpdemo.handler.BootNettyUdpSimpleChannelInboundHandler;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioDatagramChannel;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class BootNettyUdpServer {
    
    public void bind(int port) {
        log.info("-------------------------------udpServer-------------------------");
        //表示服务器连接监听线程组，专门接受 accept 新的客户端client 连接
        EventLoopGroup bossLoopGroup  = new NioEventLoopGroup();
        try {
            //1，创建netty bootstrap 启动类
            Bootstrap serverBootstrap = new Bootstrap();
            //2、设置boostrap 的eventLoopGroup线程组
            serverBootstrap = serverBootstrap.group(bossLoopGroup);
            //3、设置NIO UDP连接通道
            serverBootstrap = serverBootstrap.channel(NioDatagramChannel.class);
            //4、设置通道参数 SO_BROADCAST广播形式
            serverBootstrap = serverBootstrap.option(ChannelOption.SO_BROADCAST, true);
            //5、设置处理类 装配流水线
            serverBootstrap = serverBootstrap.handler(new BootNettyUdpSimpleChannelInboundHandler());
            //6、绑定server，通过调用sync（）方法异步阻塞，直到绑定成功
            ChannelFuture f = serverBootstrap.bind(port).sync();
            log.info(BootNettyUdpServer.class.getName()+" started and listend on "+f.channel().localAddress());
            //7、监听通道关闭事件，应用程序会一直等待，直到channel关闭
            f.channel().closeFuture().sync();
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            System.out.println("netty udp close!");
            //8 关闭EventLoopGroup，
            bossLoopGroup.shutdownGracefully();
        }
    }
}

package com.demo.udpdemo.handler;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.DatagramPacket;
import io.netty.util.CharsetUtil;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class BootNettyUdpSimpleChannelInboundHandler extends SimpleChannelInboundHandler<DatagramPacket> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
        try {
            String strdata = msg.content().toString(CharsetUtil.UTF_8);
            //打印收到的消息
            log.info("---------------------receive data--------------------------");
            log.info(strdata);
            log.info("---------------------receive data--------------------------");
            //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("ok", CharsetUtil.UTF_8), msg.sender()));
        } catch (Exception e) {
        }
    }
}

@SpringBootApplication
@EnableAsync
public class UdpDemoApplication implements CommandLineRunner {
    public static void main(String[] args) {
        SpringApplication app = new SpringApplication(UdpDemoApplication.class);
        app.run(args);
    }
    @Async
    @Override
    public void run(String... args){
       new BootNettyUdpServer().bind(51000);
    }
}

  //定义客户端ip
  private static final String SERVER_HOSTNAME = "127.0.0.1";
    // 服务器端口
    private static final int SERVER_PORT = 51000;
    // 本地发送端口
    private static final int LOCAL_PORT = 8888;
 @Test
    public void sendUdpRequestTest() {
        try {
            // 1，创建udp服务。通过DatagramSocket对象。
            DatagramSocket socket = new DatagramSocket(LOCAL_PORT);
            // 2，确定数据，并封装成数据包。DatagramPacket(byte[] buf, int length, InetAddress
            // address, int port)
            byte[] buf = "hello".getBytes();
            DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName(SERVER_HOSTNAME),
                    SERVER_PORT);
            // 3，通过socket服务，将已有的数据包发送出去。通过send方法。
            socket.send(dp);
            // 4，关闭资源。
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }