我有一个AndroidService来监听MQTT消息。下面是代码。由于某种原因，该服务能够连接和订阅频道，但无法读取消息。永远不会调用messageArrived。
public class FollowService extends Service implements MqttCallback{
private final IBinder localBinder = new FollowServiceBinder();
private final String TAG = "Service";
private MqttClient mqClient;
public class FollowServiceBinder extends Binder {
public FollowService getService() {
return FollowService.this;
}
}
public FollowService() {
}
@Override
public IBinder onBind(Intent intent) {
return localBinder;
}
@Override
public void onCreate() {
super.onCreate();
try {
mqClient = new MqttClient("tcp://192.168.1.46:1883", "sadfsfi", new MemoryPersistence());
mqClient.connect();
Log.i(TAG, "Connected to client");
}
catch(MqttException me){
Log.e(TAG, "MqttClient Exception Occured in on create!!!", me);
}
}
@Keep
public void beginFollowing(){
try {
mqClient.subscribe("test");
Log.i(TAG, "Subscribed test");
}
catch (MqttException me){
Log.e(TAG, "MqttClient Exception Occured in following!!!", me);
}
}
@Override
public void connectionLost(Throwable cause) {
Log.i(TAG, "ConnectionLost");
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
Log.i(TAG, "Delivered");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
Log.i(TAG, "Received update: " + topic + ":" + message.toString());
}
}
答案 0 :(得分：1)
有Eclipse Paho Android Service专用于Android，您可以使用而不是常规MqttClient，它可以解决您的问题（如果您确定问题不在您的MQTT服务器端）＆amp;如果您想要解决Android MQTT服务，您将来可能遇到的其他一些问题：
如果你想尝试一下：
build.gradle中的：
compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.0.3-SNAPSHOT'
compile ('org.eclipse.paho:org.eclipse.paho.android.service:1.0.3-SNAPSHOT'){
exclude module: 'support-v4'
}
compile 'com.android.support:support-v4:22.1.0'
在AndroidManifest.xml：
<uses-permission android:name="android.permission.INTERNET" />
和您的<application></application>：
<service android:name="org.eclipse.paho.android.service.MqttService" />
以下是MqttHandler.java示例：
public class MqttHandler {
protected final static String TAG = DeviceHandler.class.getSimpleName();
/**
* MQTT client
*/
private MqttAndroidClient mClient = null;
/**
* client ID used to authenticate
*/
protected String mClientId = "";
/**
* Android context
*/
private Context mContext = null;
/**
* callback for MQTT events
*/
private MqttCallback mClientCb = null;
/**
* callback for MQTT connection
*/
private IMqttActionListener mConnectionCb = null;
/**
* Sets whether the client and server should remember state across restarts and reconnects
*/
protected boolean mCleanSessionDefault = false;
/**
* Sets the connection timeout value (in seconds)
*/
protected int mTimeoutDefault = 30;
/**
* Sets the "keep alive" interval (in seconds)
*/
protected int mKeepAliveDefault = 60;
/**
* connection state
*/
private boolean connected = false;
/**
* list of message callbacks
*/
private List<IMessageCallback> mMessageCallbacksList = new ArrayList<>();
private final static String SERVER_URI = "192.168.1.46";
private final static int SERVER_PORT = 1883;
public MqttHandler(Context context) {
this.mContext = context;
this.mClientCb = new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
connected = false;
for (int i = 0; i < mMessageCallbacksList.size(); i++) {
mMessageCallbacksList.get(i).connectionLost(cause);
}
}
@Override
public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
for (int i = 0; i < mMessageCallbacksList.size(); i++) {
mMessageCallbacksList.get(i).messageArrived(topic, mqttMessage);
}
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
for (int i = 0; i < mMessageCallbacksList.size(); i++) {
mMessageCallbacksList.get(i).deliveryComplete(token);
}
}
};
}
public boolean isConnected() {
if (mClient == null)
return false;
else
return connected;
}
public void connect() {
try {
if (!isConnected()) {
MqttConnectOptions options = new MqttConnectOptions();
String serverURI = "";
options.setCleanSession(mCleanSessionDefault);
options.setConnectionTimeout(mTimeoutDefault);
options.setKeepAliveInterval(mKeepAliveDefault);
mClient = new MqttAndroidClient(mContext, "tcp://" + SERVER_URI + ":" + SERVER_PORT, mClientId);
mClient.setCallback(mClientCb);
mConnectionCb = new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken iMqttToken) {
connected = true;
for (int i = 0; i < mMessageCallbacksList.size(); i++) {
mMessageCallbacksList.get(i).onConnectionSuccess(iMqttToken);
}
}
@Override
public void onFailure(IMqttToken iMqttToken, Throwable throwable) {
connected = false;
for (int i = 0; i < mMessageCallbacksList.size(); i++) {
mMessageCallbacksList.get(i).onConnectionFailure(iMqttToken, throwable);
}
}
};
try {
mClient.connect(options, mContext, mConnectionCb);
} catch (MqttException e) {
e.printStackTrace();
}
} else {
Log.v(TAG, "cant connect - already connected");
}
} catch (IllegalArgumentException e) {
Log.v(TAG, "parameters error. cant connect");
}
}
public void disconnect() {
if (isConnected()) {
try {
mClient.disconnect(mContext, mConnectionCb);
} catch (MqttException e) {
e.printStackTrace();
}
} else {
Log.v(TAG, "cant disconnect - already disconnected");
}
}
/**
* Publish a message to MQTT server
*
* @param topic message topic
* @param message message body
* @param isRetained define if message should be retained on MQTT server
* @param listener completion listener (null allowed)
* @return
*/
public IMqttDeliveryToken publishMessage(String topic, String message, boolean isRetained, IMqttActionListener listener) {
if (isConnected()) {
MqttMessage mqttMessage = new MqttMessage(message.getBytes());
mqttMessage.setRetained(isRetained);
mqttMessage.setQos(0);
try {
return mClient.publish(topic, mqttMessage, mContext, listener);
} catch (MqttPersistenceException e) {
e.printStackTrace();
} catch (MqttException e) {
e.printStackTrace();
}
} else {
Log.e(TAG, "cant publish message. Not connected");
}
return null;
}
/**
* Subscribe to topic
*
* @param topic topic to subscribe
* @param listener completion listener (null allowed)
* @return
*/
public void subscribe(String topic, IMqttActionListener listener) {
if (isConnected()) {
try {
mClient.subscribe(topic, 0, mContext, listener);
} catch (MqttException e) {
e.printStackTrace();
}
} else {
Log.e(TAG, "cant publish message. Not connected");
}
}
/**
* Unsubscribe a topic
*
* @param topic topic to unsubscribe
* @param listener completion listener (null allowed)
*/
public void unsubscribe(String topic, IMqttActionListener listener) {
if (isConnected()) {
try {
mClient.unsubscribe(topic, mContext, listener);
} catch (MqttException e) {
e.printStackTrace();
}
} else {
Log.e(TAG, "cant publish message. Not connected");
}
}
public void addCallback(IMessageCallback callback) {
mMessageCallbacksList.add(callback);
}
}
使用此监听器IMessageCallback.java：
public interface IMessageCallback {
/**
* This method is called when the connection to the server is lost.
*
* @param cause the reason behind the loss of connection.
*/
void connectionLost(Throwable cause);
/**
* This method is called when a message arrives from the server.
*
* @param topic name of the topic on the message was published to
* @param mqttMessage the actual message
* @throws Exception
*/
void messageArrived(String topic, MqttMessage mqttMessage) throws Exception;
/**
* Called when delivery for a message has been completed, and all acknowledgments have been received.
*
* @param messageToken he delivery token associated with the message.
*/
void deliveryComplete(IMqttDeliveryToken messageToken);
/**
* Called when connection is established
*
* @param iMqttToken token for this connection
*/
void onConnectionSuccess(IMqttToken iMqttToken);
/**
* Called when connection has failed
*
* @param iMqttToken token when failure occured
* @param throwable exception
*/
void onConnectionFailure(IMqttToken iMqttToken, Throwable throwable);
/**
* Called when disconnection is successfull
*
* @param iMqttToken token for this connection
*/
void onDisconnectionSuccess(IMqttToken iMqttToken);
/**
* Called when disconnection failed
*
* @param iMqttToken token when failure occured
* @param throwable exception
*/
void onDisconnectionFailure(IMqttToken iMqttToken, Throwable throwable);
}
您可以这样称呼它：
final MqttHandler mqttHandler = new MqttHandler(mContext);
mqttHandler.addCallback(new IMessageCallback() {
@Override
public void connectionLost(Throwable cause) {
Log.v(TAG, "connectionLost");
}
@Override
public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
Log.v(TAG, "messageArrived : " + topic + " : " + new String(mqttMessage.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken messageToken) {
try {
Log.v(TAG, "deliveryComplete : " + new String(messageToken.getMessage().getPayload()));
} catch (MqttException e) {
e.printStackTrace();
}
}
@Override
public void onConnectionSuccess(IMqttToken iMqttToken) {
Log.v(TAG, "connection success");
mqttHandler.subscribe("test", new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.v(TAG, "subscribe success");
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.e(TAG, "subscribe failure");
}
});
}
@Override
public void onConnectionFailure(IMqttToken iMqttToken, Throwable throwable) {
Log.v(TAG, "connection failure");
}
@Override
public void onDisconnectionSuccess(IMqttToken iMqttToken) {
Log.v(TAG, "disconnection success");
}
@Override
public void onDisconnectionFailure(IMqttToken iMqttToken, Throwable throwable) {
Log.v(TAG, "disconnection failure");
}
});
mqttHandler.connect();
您可以在Paho Mqtt Android客户端here
中找到完整的工作用例