JAVA-SDK使用(MQTT)__SDK使用参考_设备端接入手册_阿里云物联网套件-阿里云

        InputStream is = new ByteArrayInputStream(pubKeyByteContent);
        InputStream caInput = new BufferedInputStream(is);
        CertificateFactory cf = CertificateFactory.getInstance("X.509");
        Certificate ca = null;
        try {
            ca = cf.generateCertificate(caInput);
        } catch (CertificateException e) {
            e.printStackTrace();
        } finally {
            caInput.close();
        }
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);
        SSLContext context = SSLContext.getInstance("TLSV1.2");
        context.init(null, tmf.getTrustManagers(), null);
        SSLSocketFactory socketFactory = context.getSocketFactory();

第三步

与阿里云建立TLS/SSL连接.

需要注意的是在配置MQTT连接时， Connect协议当中 clientId 属性值为 productKey:deviceId username 属性值为 ToUpperCase(MD5_32(productKey+productSecret+deviceId+deviceSecret)) 这样以便阿里云对当前连接的有效性进行验证.

    final String topic = Config.topic;
    String broker = "ssl://" + targetServer;
    //客户端ID格式: productKey + deviceId.
    String clientId = Config.productKey + ":" + deviceId;
    MemoryPersistence persistence = new MemoryPersistence();
    SSLSocketFactory socketFactory = createSSLSocket(stest);
    final MqttClient sampleClient = new MqttClient(broker, clientId, persistence);
    MqttConnectOptions connOpts = new MqttConnectOptions();
    connOpts.setMqttVersion(4);// MQTT 3.1.1
    connOpts.setSocketFactory(socketFactory);
    String signUserName = signUserName(deviceId);
    connOpts.setUserName(signUserName);
    connOpts.setKeepAliveInterval(65);
    System.out.println("进行连接, 目的地: " + broker);
    sampleClient.connect(connOpts);

第四步

进行消息Publish.

    String content = "Message From Device:" + Config.deviceName2;
    MqttMessage message = new MqttMessage(content.getBytes());
    message.setQos(1);
    sampleClient.publish(topic, message);
    System.out.println("消息发布成功!");