Paho-mqtt在不同类的android java中回调

2023年2月19日 184次阅读

我刚刚开始使用
Java
Android编程,甚至是Java编程,我想使用某个MqttHandler类实现Paho MQTT Android服务,我想将回调设置为MqttHandler类的参数.关于回调的其他答案一般建议使用接口类,但我不知道它是如何工作的.这是我尝试过的：

public interface InterfaceMqttCallback extends MqttCallbackExtended{
    @Override
    public void connectComplete(boolean b, String s);

    @Override
    public void connectionLost(Throwable throwable);

    @Override
    public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception ;

    @Override
    public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken);

}

MqttHandler类构造函数：

public MqttHandler(Context context, InterfaceMqttCallback mqttCallbackExtended){
    mqttAndroidClient = new MqttAndroidClient(context, serverUri, clientId);
    mqttAndroidClient.setCallback(mqttCallbackExtended);
    connect();
}

初始化MqttHandler的Activity中的函数：

private void startMqtt(){

    mqttHandler = new MqttHandler(getApplicationContext(), new InterfaceMqttCallback() {
        @Override
        public void connectComplete(boolean b, String s) {
            Log.w("Anjing", s);
        }

        @Override
        public void connectionLost(Throwable throwable) {

        }

        @Override
        public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
            Log.w("Anjing", mqttMessage.toString());
        }

        @Override
        public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

        }
    });

}

但是当我测试它时,我认为回调没有设置,因为没有收到任何消息.那么我尝试直接在MqttHandler中设置回调并且它可以工作,接收消息.

public MqttHandler(Context context, InterfaceMqttCallback mqttCallbackExtended){
    mqttAndroidClient = new MqttAndroidClient(context, serverUri, clientId);
    mqttAndroidClient.setCallback(new InterfaceMqttCallback() {
        @Override
        public void connectComplete(boolean b, String s) {
            Log.w("mqtt", s);
        }

        @Override
        public void connectionLost(Throwable throwable) {

        }

        @Override
        public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
            Log.w("Anjing", mqttMessage.toString());
        }

        @Override
        public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

        }
    });
    connect();
}

所以有什么问题？提前致谢..

编辑：当然我可以将MqttHandler类中的mqttAndroidClient变量设置为public,但它是否安全？

最佳答案 设置回调处理程序的正确方法是在MQTT客户端中设置它,如下所示：

        public class MTTConnector { 
            public void connect {
              MqttAndroidClient mqttClient = new MqttAndroidClient(BaseApplication.getAppContext(), broker, MQTT_CLIENT_ID); 
              mqttClient.setCallback(new MqttCallbackHandler(BaseApplication.getAppContext()));
          }
        }

    public class MqttCallbackHandler implements MqttCallbackExtended {
    @Override
        public void connectComplete(boolean b, String s) {
            Log.w("mqtt", s);
        }

        @Override
        public void connectionLost(Throwable throwable) {

        }

        @Override
        public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
            Log.w("Anjing", mqttMessage.toString());
        }

        @Override
        public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

        }
  }

如果您使用的是最新版本,则回调需要实现MqttCallbackExtended类,有关在线GitHub项目的更多详细信息,请参阅以下链接.

MqttCallbackExtended.java

在您的活动内部初始化MTTConnector并调用connect.

希望这个帮助.

干杯！

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