SpringBoot 開啟 UDP 服務，進行接收 UDP，及傳送 UDP，這裡依賴的是 SpringBoot 內建 integration 包

1. Config

新增 Jar，下面用的是 SpringBoot 內建 integration 依賴

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-integration</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>
 
<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-ip</artifactId>
</dependency>

2. Receiving

/**
 * UDP訊息接收服務*/
@Configuration
public class UdpServer {
    private static final Logger logger = LoggerFactory.getLogger(UdpServer.class);
 
    @Value("${udp.port}")
    private Integer udpPort;/**
     * UDP訊息接收服務寫法一
     * https://docs.spring.io/spring-integration/reference/html/ip.html
 
#inbound-udp-adapters-java-configuration
     *
     * @param
     * @return org.springframework.integration.ip.udp.UnicastReceivingChannelAdapter*/
    /*@Bean
    public UnicastReceivingChannelAdapter unicastReceivingChannelAdapter() {
        // 例項化一個UDP訊息接收服務
        UnicastReceivingChannelAdapter unicastReceivingChannelAdapter = new UnicastReceivingChannelAdapter(udpPort);
        // unicastReceivingChannelAdapter.setOutputChannel(new DirectChannel());
        unicastReceivingChannelAdapter.setOutputChannelName("udpChannel");
        logger.info("UDP服務啟動成功，埠號為: {}", udpPort);
        return unicastReceivingChannelAdapter;
    }
 
*/
 
    /**
     * UDP訊息接收服務寫法二
     * https://docs.spring.io/spring-integration/reference/html/ip.html#inbound-udp-adapters-java-dsl-configuration
     *
     * @param
     * @return org.springframework.integration.dsl.IntegrationFlow*/
    @Bean
    public IntegrationFlow integrationFlow() {
        logger.info("UDP服務啟動成功，埠號為: {}", udpPort);
        return IntegrationFlows.from(Udp.inboundAdapter(udpPort)).channel("udpChannel").get();
    }
 
    /**
     * 轉換器
     *
     * @param payload
  　　* @param headers
     * @return java.lang.String*/
    @Transformer(inputChannel = "udpChannel", outputChannel = "udpFilter")
    public String transformer(@Payload byte[] payload, @Headers Map<String, Object> headers) {
        String message = new String(payload);
        // 轉換為大寫
        // message = message.toUpperCase();
        // 向客戶端響應，還不知道怎麼寫
        return message;
    }
 
    /**
     * 過濾器*/
    @Filter(inputChannel = "udpFilter", outputChannel = "udpRouter")
    public boolean filter(String message, @Headers Map<String, Object> headers) {
        // 獲取來源Id
        String id = headers.get("id").toString();
        // 獲取來源IP，可以進行IP過濾
        String ip = headers.get("ip_address").toString();
        // 獲取來源Port
        String port = headers.get("ip_port").toString();
        // 資訊資料過濾
        /*if (message.indexOf("-") < 0) {
            // 沒有-的資料會被過濾
            return false;
        }*/
        return true;
    }
 
    /**
     * 路由分發處理器*/
    @Router(inputChannel = "udpRouter")
    public String router(String message, @Headers Map<String, Object> headers) {
        // 獲取來源Id
        String id = headers.get("id").toString();
        // 獲取來源IP，可以進行IP過濾
        String ip = headers.get("ip_address").toString();
        // 獲取來源Port
        String port = headers.get("ip_port").toString();
        // 篩選，走那個處理器
        if (false) {
            return "udpHandle2";
        }
        return "udpHandle1";
    }
 
    /**
     * 最終處理器1*/
    @ServiceActivator(inputChannel = "udpHandle1")
    public void udpMessageHandle(String message) throws Exception {
        // 可以進行非同步處理
        businessService.udpHandleMethod(message);
        logger.info("UDP1:" + message);
    }
 
    /**
     * 最終處理器2*/
    @ServiceActivator(inputChannel = "udpHandle2")
    public void udpMessageHandle2(String message) throws Exception {
        logger.info("UDP2:" + message);
    }
 
}

3. Sending

3.1. UdpSimpleClient

/**
 * 預設傳送方式*/
@Service
public class UdpSimpleClient {
    private final static Logger logger = LoggerFactory.getLogger(UdpSimpleClient.class);
 
    @Value("${udp.port}")
    private Integer udpPort;
 
    public void sendMessage(String message) {
        logger.info("傳送UDP: {}", message);
        InetSocketAddress inetSocketAddress = new InetSocketAddress("localhost", udpPort);
        byte[] udpMessage = message.getBytes();
        DatagramPacket datagramPacket = null;
        try (DatagramSocket datagramSocket = new DatagramSocket()) {
            datagramPacket = new DatagramPacket(udpMessage, udpMessage.length, inetSocketAddress);
            datagramSocket.send(datagramPacket);
        } catch (IOException e) {
            logger.error(e.getMessage(), e);
        }
        logger.info("傳送成功");
    }
}

3.2. UdpIntegrationClient

/**
 * IntegrationClientConfig*/
@Configuration
public class UdpIntegrationClientConfig {
 
    @Value("${udp.port}")
    private Integer udpPort;
 
    @Bean
    @ServiceActivator(inputChannel = "udpOut")
    public UnicastSendingMessageHandler unicastSendingMessageHandler() {
        UnicastSendingMessageHandler unicastSendingMessageHandler = new UnicastSendingMessageHandler("localhost", udpPort);
        return unicastSendingMessageHandler;
    }
 
}

/**
 * Integration傳送方式*/
@Service
public class UdpIntegrationClient {
 
    private final static Logger logger = LoggerFactory.getLogger(UdpIntegrationClient.class);
 
    @Autowired
    private UnicastSendingMessageHandler unicastSendingMessageHandler;
 
    public void sendMessage(String message) {
        logger.info("傳送UDP: {}", message);
        unicastSendingMessageHandler.handleMessage(MessageBuilder.withPayload(message).build());
        logger.info("傳送成功");
    }
 
}