ANDROID-MQTT:无法连接到服务器 (32103) [英] ANDROID-MQTT :Unable to connect to server (32103)
问题描述
我正在尝试在 Android 中学习基本的 MQTT 集成.我正在使用 mosquitto 代理来发布和订阅消息.我在真实设备上运行代码并收到此异常:
I am trying to learn basic MQTT integration in Android. I am using a mosquitto broker to publish and subscribe messages. I am running the code on a real device and getting this exception :
Unable to connect to server (32103) - java.net.ConnectException:
failed to connect to /192.168.0.103 (port 1883) after
30000ms: isConnected failed: ECONNREFUSED
这是我的代码:
public class HomeActivity extends AppCompatActivity{
private MqttAndroidClient client;
private final MemoryPersistence persistence = new MemoryPersistence();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final MqttAndroidClient mqttAndroidClient = new MqttAndroidClient(this.getApplicationContext(), "tcp://192.168.0.103:1883", "androidSampleClient", persistence);
mqttAndroidClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
System.out.println("Connection was lost!");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("Message Arrived!: " + topic + ": " + new String(message.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("Delivery Complete!");
}
});
MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
mqttConnectOptions.setCleanSession(true);
try {
mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
System.out.println("Connection Success!");
try {
System.out.println("Subscribing to /test");
mqttAndroidClient.subscribe("/test", 0);
System.out.println("Subscribed to /test");
System.out.println("Publishing message..");
mqttAndroidClient.publish("/test", new MqttMessage("Hello world testing..!".getBytes()));
} catch (MqttException ex) {
}
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
System.out.println("Connection Failure!");
System.out.println("throwable: " + exception.toString());
}
});
} catch (MqttException ex) {
System.out.println(ex.toString());
}
}
}
我尝试使用不同的端口,但错误是相同的.谁能帮助我做错了什么?
I've tried using different ports but the error is same. Can anyone help what am i doing wrong?
推荐答案
在开始时,您需要了解不同的实现是如何工作的.看看我的实现.我为 MQTT 特定的东西使用了一个单独的类.
As you are getting started, you need to see see how different implementations work. Take a look at my implementation. I use a separated class for MQTT specific stuff.
MqttUtil.java
public class MqttUtil {
private static final String MQTT_TOPIC = "test/topic";
private static final String MQTT_URL = "tcp://localhost:1883";
private static boolean published;
private static MqttAndroidClient client;
private static final String TAG = MqttUtil.class.getName();
public static MqttAndroidClient getClient(Context context){
if(client == null){
String clientId = MqttClient.generateClientId();
client = new MqttAndroidClient(context, MQTT_URL, clientId);
}
if(!client.isConnected())
connect();
return client;
}
private static void connect(){
MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
mqttConnectOptions.setCleanSession(true);
mqttConnectOptions.setKeepAliveInterval(30);
try{
client.connect(mqttConnectOptions, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.d(TAG, "onSuccess");
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.d(TAG, "onFailure. Exception when connecting: " + exception);
}
});
}catch (Exception e) {
Log.e(TAG, "Error while connecting to Mqtt broker : " + e);
e.printStackTrace();
}
}
public static void publishMessage(final String payload){
published = false;
try {
byte[] encodedpayload = payload.getBytes();
MqttMessage message = new MqttMessage(encodedpayload);
client.publish(MQTT_TOPIC, message);
published = true;
Log.i(TAG, "message successfully published : " + payload);
} catch (Exception e) {
Log.e(TAG, "Error when publishing message : " + e);
e.printStackTrace();
}
}
public static void close(){
if(client != null) {
client.unregisterResources();
client.close();
}
}
}
而且您可以简单地在 HomeActivity 中使用它.在下面检查:
And you can simply use it in your HomeActivity. Check it below:
public class HomeActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get Mqtt client singleton instance
MqttUtil.getClient(this);
// Publish a sample message
MqttUtil.publishMessage("Hello Android MQTT");
}
}
出于测试目的,请使用您的 Mosquitto 子客户端并查看您是否收到消息.
For testing purposes, use your Mosquitto sub client and see if you get the message.
希望有帮助!
这篇关于ANDROID-MQTT:无法连接到服务器 (32103)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!