Java对接CoAP的完整方案

<!-- core 核心 -->
<dependency>
    <groupId>org.eclipse.californium</groupId>
    <artifactId>californium-core</artifactId>
    <version>3.9.0</version>
</dependency>
<!-- coap协议标准封装 -->
<dependency>
    <groupId>org.eclipse.californium</groupId>
    <artifactId>element-connector</artifactId>
    <version>3.9.0</version>
</dependency>
<!-- DTLS 加密（设备安全通信必加） -->
<dependency>
    <groupId>org.eclipse.californium</groupId>
    <artifactId>scandium-core</artifactId>
    <version>3.9.0</version>
</dependency>

import org.eclipse.californium.core.CoapClient;
import org.eclipse.californium.core.CoapResponse;
import org.eclipse.californium.core.coap.MediaTypeRegistry;

public class CoapSimpleClient {
    public static void main(String[] args) {
        // coap://IP:端口/资源路径
        String uri = "coap://127.0.0.1:5683/sensor/temp";
        CoapClient client = new CoapClient(uri);

        try {
            // 1. GET 请求（读取设备数据）
            CoapResponse getResp = client.get();
            if (getResp.isSuccess()) {
                System.out.println("GET 响应：" + getResp.getResponseText());
                System.out.println("状态码：" + getResp.getCode());
            }

            // 2. PUT 请求（下发配置，携带JSON）
            String payload = "{\"temp\":25}";
            CoapResponse putResp = client.put(
                payload,
                MediaTypeRegistry.APPLICATION_JSON
            );

            // 3. POST 请求（上报数据/执行指令）
            CoapResponse postResp = client.post(
                "open",
                MediaTypeRegistry.TEXT_PLAIN
            );

            // 4. DELETE
            client.delete();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            client.close();
        }
    }
}

import org.eclipse.californium.core.CoapResource;
import org.eclipse.californium.core.CoapServer;
import org.eclipse.californium.core.server.resources.CoapExchange;

public class CoapSimpleServer {
    public static void main(String[] args) {
        CoapServer server = new CoapServer(5683); // 默认5683端口

        // 定义资源 /sensor/temp
        CoapResource tempResource = new CoapResource("temp") {
            @Override
            public void handleGET(CoapExchange exchange) {
                // 设备读取温度
                exchange.respond("26.5 ℃");
            }

            @Override
            public void handlePOST(CoapExchange exchange) {
                // 设备POST上报数据
                String data = exchange.getRequestText();
                System.out.println("设备上报：" + data);
                exchange.respond(201, "ok");
            }

            @Override
            public void handlePUT(CoapExchange exchange) {
                String cfg = exchange.getRequestText();
                System.out.println("下发配置：" + cfg);
                exchange.respond("update success");
            }
        };

        CoapResource sensorRoot = new CoapResource("sensor");
        sensorRoot.add(tempResource);
        server.add(sensorRoot);

        server.start();
        System.out.println("CoAP Server 启动，端口5683");
    }
}

// 客户端订阅资源变化
client.observe(resp -> {
    System.out.println("推送数据：" + resp.getResponseText());
});

// coaps 加密地址，需加载证书
CoapClient secureClient = new CoapClient("coaps://127.0.0.1:5684/device");

<dependency>
    <groupId>com.github.svetleishaya</groupId>
    <artifactId>coap-java</artifactId>
    <version>1.4.0</version>
</dependency>