MQTT客户端安卓代码

当然，我可以提供一个简单的MQTT客户端的安卓代码示例。你可以使用Eclipse或Android Studio进行开发。以下是一个基本的示例代码：

首先，你需要在Gradle文件中添加MQTT库的依赖项。在app级别的build.gradle文件中添加以下代码：

dependencies {
    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.5'
}

然后，在你的活动（Activity）或片段（Fragment）中，创建一个MQTT客户端并定义回调函数。以下是一个简单的例子：

import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

public class MainActivity extends AppCompatActivity {

    private static final String MQTT_BROKER = "tcp://mqtt.example.com:1883";
    private static final String MQTT_CLIENT_ID = "android-client";
    private static final String MQTT_TOPIC = "your-mqtt-topic";

    private MqttClient mqttClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        connectMQTTClient();
    }

    private void connectMQTTClient() {
        try {
            mqttClient = new MqttClient(MQTT_BROKER, MQTT_CLIENT_ID, new MemoryPersistence());
            MqttConnectOptions options = new MqttConnectOptions();
            options.setCleanSession(true);
            mqttClient.connect(options);

            mqttClient.setCallback(new MqttCallback() {
                @Override
                public void connectionLost(Throwable cause) {
                    // 处理连接丢失的情况
                }

                @Override
                public void messageArrived(String topic, MqttMessage message) throws Exception {
                    // 处理收到的消息
                    String payload = new String(message.getPayload());
                    Log.d("MQTT", "Received message: " + payload);
                }

                @Override
                public void deliveryComplete(IMqttDeliveryToken token) {
                    // 处理交付完成的情况
                }
            });

            mqttClient.subscribe(MQTT_TOPIC, 0);
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        try {
            if (mqttClient != null && mqttClient.isConnected()) {
                mqttClient.disconnect();
            }
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }
}

请注意，在上面的示例中，你需要将`MQTT_BROKER`更改为你的MQTT代理服务器的地址和端口，将`MQTT_TOPIC`更改为你要订阅的主题。

这只是一个简单的示例，你可以根据自己的需求进行扩展和定制。希望对你有帮助！