dependencies 
    compile 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
    compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.1'

2.在project下Gradle中添加：

repositories 
        maven 
            url "https://repo.eclipse.org/content/repositories/paho-releases/"

第二步：添加权限

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

第三步：开启服务

在AndroidMainFest.xml中开启MQTT服务：

	<!-- Mqtt Service -->
    <service android:name="org.eclipse.paho.android.service.MqttService" />

第四步：订阅器的实现

前面几步准备工作完成之后我们就可以正式开启今天的任务。

1.首先创建MqttAndroidClient和MqttConnectOptions，这两员大将一个是负责连接，一个是复杂属性设置的：

MqttAndroidClient mqttAndroidClient = new MqttAndroidClient(getApplicationContext(), serverUri, clientId);

MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();

2.然后去设置MqttConnectOptions属性：

	// 配置MQTT连接
	mqttConnectOptions.setAutomaticReconnect(true);
    mqttConnectOptions.setCleanSession(false);
    mqttConnectOptions.setUserName(null);
    mqttConnectOptions.setPassword(null);
    mqttConnectOptions.setConnectionTimeout(30);  //超时时间
    mqttConnectOptions.setKeepAliveInterval(60); //心跳时间,单位秒
    mqttConnectOptions.setAutomaticReconnect(true);//自动重连

以上是一些常用的属性，更多属性可以查看官网：Class MqttConnectOptions API

3.创建MQTT连接

mqttAndroidClient.connect(mqttConnectOptions);

4.设置监听

mqttAndroidClient.setCallback(new MqttCallbackExtended() 
            @Override
            public void connectComplete(boolean reconnect, String serverURI) 
                Log.e(TAG, "reconnect ---> " + reconnect + "       serverURI--->" + serverURI);
            

            @Override
            public void connectionLost(Throwable cause) 
                Log.e(TAG, "cause ---> " + cause);
            

            @Override
            public void messageArrived(String topic, MqttMessage message) throws Exception 
                Log.e(TAG, "topic ---> " + topic + "       message--->" + message);
                startNotification(message);
            

            @Override
            public void deliveryComplete(IMqttDeliveryToken token) 
                Log.e(TAG, "token ---> " + token);
            
        );

5.订阅消息

我们在上面connectComplete方法里面去订阅消息

    final String subscriptionTopic = "exampleAndroidTopic";

	private void subscribeToTopic() 
        try 
            mqttAndroidClient.subscribe(subscriptionTopic, 0, null, new IMqttActionListener() 
                @Override
                public void onSuccess(IMqttToken asyncActionToken) 
                    Log.e(TAG, "onFailure ---> " + asyncActionToken);
                

                @Override
                public void onFailure(IMqttToken asyncActionToken, Throwable exception) 
                    Log.e(TAG, "onFailure ---> " + exception);
                
            );
         catch (MqttException e) 
            Log.e(TAG, "subscribeToTopic is error");
            e.printStackTrace();

到这里大公告成，已经可以接收到发送的消息了。
接下来去实现我们的Notification。

Notification通知栏

Notification使用非常简单，这里就不详细介绍，主要见代码：

	private NotificationManager notificationManager ;
    private NotificationCompat.Builder notificationBuilder ;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initNotification();
	
	
	private void initNotification() 
        notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        notificationBuilder = new NotificationCompat.Builder(this);

初始化完成之后我们在上面监听器的messageArrived方法中去接收消息。

@Override
public void messageArrived(String topic, MqttMessage message) throws Exception 
    Log.e(TAG, "topic ---> " + topic + "       message--->" + message);
    startNotification(message);

private void startNotification(MqttMessage message) 
        // params
        Bitmap largeIcon = ((BitmapDrawable) getResources().getDrawable(R.mipmap.ic_launcher_round)).getBitmap();
        String info = message.toString();

        Intent intent = new Intent(MainActivity.this,JumpActivity.class);
        intent.putExtra(MESSAGE,info);

        notificationBuilder.setLargeIcon(largeIcon)
                .setSmallIcon(R.mipmap.ic_launcher_round)
                .setContentTitle("推送消息啦")
                .setContentText(info)
                .setTicker(info)
                .setContentIntent(PendingIntent.getActivity(MainActivity.this, 0, intent, 0));

        Notification notification = notificationBuilder.getNotification();

        notificationManager.notify(NOTIFICATION_ID, notification);

好啦，就是这么简单，记下来让我们看一下展示效果！

⚠️：切记，地址和端口一定要匹配不让玩死也收不到消息！！！！！！！！！！！！！！！！！！！！！！！！