Question

我对Android使用MQTT完全不熟悉，我正在尝试这段代码：

public class MQTTActivity extends AppCompatActivity {
private HistoryAdapter mAdapter;
MqttAndroidClient mqttAndroidClient;

final String serverUri = "tcp://iot.eclipse.org:1883";

String clientId = "ExampleAndroidClient";
final String subscriptionTopic = "exampleAndroidTopic";
final String publishTopic = "exampleAndroidPublishTopic";
final String publishMessage = "Hello World!";


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


    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            publishMessage();
        }
    });


    RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.history_recycler_view);
    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    mAdapter = new HistoryAdapter(new ArrayList<String>());
    mRecyclerView.setAdapter(mAdapter);

    clientId = clientId + System.currentTimeMillis();

    mqttAndroidClient = new MqttAndroidClient(getApplicationContext(), serverUri, clientId);
    mqttAndroidClient.setCallback(new MqttCallbackExtended() {
        @Override
        public void connectComplete(boolean reconnect, String serverURI) {

            if (reconnect) {
                addToHistory("Reconnected to : " + serverURI);
                // Because Clean Session is true, we need to re-subscribe
                subscribeToTopic();
            } else {
                addToHistory("Connected to: " + serverURI);
            }
        }

        @Override
        public void connectionLost(Throwable cause) {
            addToHistory("The Connection was lost.");
        }

        @Override
        public void messageArrived(String topic, MqttMessage message) throws Exception {
            addToHistory("Incoming message: " + new String(message.getPayload()));
        }

        @Override
        public void deliveryComplete(IMqttDeliveryToken token) {

        }
    });

    MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
    mqttConnectOptions.setAutomaticReconnect(true);
    mqttConnectOptions.setCleanSession(false);







    try {
        //addToHistory("Connecting to " + serverUri);
        mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
            @Override
            public void onSuccess(IMqttToken asyncActionToken) {
                DisconnectedBufferOptions disconnectedBufferOptions = new DisconnectedBufferOptions();
                disconnectedBufferOptions.setBufferEnabled(true);
                disconnectedBufferOptions.setBufferSize(100);
                disconnectedBufferOptions.setPersistBuffer(false);
                disconnectedBufferOptions.setDeleteOldestMessages(false);
                mqttAndroidClient.setBufferOpts(disconnectedBufferOptions);
                subscribeToTopic();
            }

            @Override
            public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                addToHistory("Failed to connect to: " + serverUri);
            }
        });


    } catch (MqttException ex){
        ex.printStackTrace();
    }

}

private void addToHistory(String mainText){
    System.out.println("LOG: " + mainText);
    mAdapter.add(mainText);
    Snackbar.make(findViewById(android.R.id.content), mainText, Snackbar.LENGTH_LONG)
            .setAction("Action", null).show();

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.

    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement

    return super.onOptionsItemSelected(item);
}

public void subscribeToTopic(){
    try {
        mqttAndroidClient.subscribe(subscriptionTopic, 0, null, new IMqttActionListener() {
            @Override
            public void onSuccess(IMqttToken asyncActionToken) {
                addToHistory("Subscribed!");
            }

            @Override
            public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                addToHistory("Failed to subscribe");
            }
        });

        // THIS DOES NOT WORK!
        mqttAndroidClient.subscribe(subscriptionTopic, 0, new IMqttMessageListener() {
            @Override
            public void messageArrived(String topic, MqttMessage message) throws Exception {
                // message Arrived!
                System.out.println("Message: " + topic + " : " + new String(message.getPayload()));
            }
        });

    } catch (MqttException ex){
        System.err.println("Exception whilst subscribing");
        ex.printStackTrace();
    }
}

public void publishMessage(){

    try {
        MqttMessage message = new MqttMessage();
        message.setPayload(publishMessage.getBytes());
        mqttAndroidClient.publish(publishTopic, message);
        addToHistory("Message Published");
        if(!mqttAndroidClient.isConnected()){
            addToHistory(mqttAndroidClient.getBufferedMessageCount() + " messages in buffer.");
        }
    } catch (MqttException e) {
        System.err.println("Error Publishing: " + e.getMessage());
        e.printStackTrace();
    }
}}

我得到了这个例外：

FATAL EXCEPTION: main
java.lang.RuntimeException: Error receiving broadcast Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x8000010 (has extras) } in org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver@41c79f18
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:810)
at android.os.Handler.handleCallback(Handler.java:800)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5455)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:966)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:733)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.SecurityException: Neither user 10083 nor current process has android.permission.WAKE_LOCK.
at android.os.Parcel.readException(Parcel.java:1428)
at android.os.Parcel.readException(Parcel.java:1382)
at android.os.IPowerManager$Stub$Proxy.acquireWakeLock(IPowerManager.java:301)
at android.os.PowerManager$WakeLock.acquireLocked(PowerManager.java:746)
at android.os.PowerManager$WakeLock.acquire(PowerManager.java:715)
at org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver.onReceive(MqttService.java:821)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:800)
at android.os.Handler.handleCallback(Handler.java:800) 
at android.os.Handler.dispatchMessage(Handler.java:100) 
at android.os.Looper.loop(Looper.java:194) 
at android.app.ActivityThread.main(ActivityThread.java:5455) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:525) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:966) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:733) 
at dalvik.system.NativeStart.main(Native Method)

我已经添加了网络和Internet连接渗透。我将mqtt服务添加到我的清单中。

我似乎无法找到代码出错的地方？

Answer 1

问题是来自堆栈跟踪的这一行：

Caused by: java.lang.SecurityException: Neither user 10083 nor current process has android.permission.WAKE_LOCK.

您需要在清单中请求WAKE_LOCK以及网络访问。

Answer 2

问题与 MQTT 协议无关，但与应用正在做的其他事情有关......

看起来您正试图通知用户某些事情（可能是新的消息）

为了做到这一点，你需要在android的清单中声明使用permisions，在你的情况下如下：

<uses-permission android:name="android.permission.WAKE_LOCK" />

Answer 3

使用此在清单文件中添加权限

 <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

并添加内部应用程序标记

<service android:name="org.eclipse.paho.android.service.MqttService" >
        </service>

在build.gradle

中

repositories {
    maven {
        url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
    }
}

implementation('org.eclipse.paho:org.eclipse.paho.android.service:1.0.2') {
        exclude module: 'support-v4'
    }

并在您的活动中使用代码

String clientId = MqttClient.generateClientId();
      client = new MqttAndroidClient(MainActivity.this, "tcp://broker.hivemq.com:1883",clientId);
        try {

            token = client.connect(options);
            token.setActionCallback(new IMqttActionListener(){
                @Override
                public void onSuccess(IMqttToken asyncActionToken) {
                    Toast.makeText(getApplicationContext(),"success",Toast.LENGTH_SHORT).show();
                    Log.d("connect", "onSuccess");

                    publishmessage();
                }
                @Override
                public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                    Toast.makeText(getApplicationContext(),"success",Toast.LENGTH_SHORT).show();
                    Log.d("connect", "onFailure");
                }
            });
        } catch (MqttException e) {
            e.printStackTrace();
        }

在Android中设置MQTT连接

3 个答案: