android studio连接EMQX并接受信息

要在Android Studio中连接EMQX并接收信息，您需要执行以下步骤：

1. 在EMQX中创建一个新的MQTT Broker，或者使用现有的Broker。
2. 在Android Studio中安装MQTT客户端库，例如Eclipse Paho。
3. 在Android Studio中创建一个新的项目，并添加Paho MQTT客户端库的依赖项。
4. 编写一个Java类来连接EMQX Broker，订阅一个主题并接收消息。

以下是一个简单的示例代码，可以连接到EMQX Broker，订阅主题，并在接收到新消息时打印消息内容：

import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

public class MQTTSubscriber {

    public static void main(String[] args) {

        String topic = "test/topic";
        int qos = 1;
        String broker = "tcp://emqx.example.com:1883";
        String clientId = "AndroidClient";
        MemoryPersistence persistence = new MemoryPersistence();

        try {
            MqttClient mqttClient = new MqttClient(broker, clientId, persistence);
            MqttConnectOptions connOpts = new MqttConnectOptions();
            connOpts.setCleanSession(true);
            System.out.println("Connecting to broker: " + broker);
            mqttClient.connect(connOpts);
            System.out.println("Connected");
            mqttClient.subscribe(topic, qos);
            System.out.println("Subscribed to topic: " + topic);

            mqttClient.setCallback(new MqttCallback() {
                public void messageArrived(String topic, MqttMessage message) throws Exception {
                    System.out.println("Received message: " + new String(message.getPayload()));
                }

                public void deliveryComplete(IMqttDeliveryToken token) {
                }

                public void connectionLost(Throwable cause) {
                }
            });

        } catch (MqttException me) {
            System.out.println("reason " + me.getReasonCode());
            System.out.println("msg " + me.getMessage());
            System.out.println("loc " + me.getLocalizedMessage());
            System.out.println("cause " + me.getCause());
            System.out.println("excep " + me);
            me.printStackTrace();
        }
    }
}

请注意，此示例仅用于演示目的，实际应用程序需要在错误处理和其他方面进行更多的代码编写。