Android中连接MQTT服务器实现发布一个消息推送给订阅者(附代码下载)

妖狐艹你老母 2023-10-05 17:32 4阅读 0赞

## 场景 ##

Windows上Mqtt服务器搭建与使用客户端工具MqttBox进行测试：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/112305328][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_112305328]

SpringBoot整合MQTT服务器实现消息的发送与订阅(推送消息与接收推送)：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/112394731][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_112394731]

在上面实现了将MQTT服务器搭建成功并且在SpringBoot中实现消息的发送与订阅。

那么在Android中怎样实现消息的发布。

注：

博客：  
[https://blog.csdn.net/badao\_liumang\_qizhi][https_blog.csdn.net_badao_liumang_qizhi]  
关注公众号  
霸道的程序猿  
获取编程相关电子书、教程推送与免费下载。

## 实现 ##

首先你需要将MQTT服务器搭建好，参照上面的博客。

然后新建一个Android项目，在build.gradle中引入mqtt依赖

//mqtt
        implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
        implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'

然后在AndroidManifest.xml中添加网络权限

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

在项目包下新建一个mqtt包，然后新建一个service叫MQTTService用来实现项目启动后连接到mqtt服务器的一些初始化操作

package com.badao.androidmqttpublishclient.mqtt;
    
    import android.app.Service;
    import android.content.Intent;
    import android.os.IBinder;
    import android.util.Log;
    
    import androidx.annotation.Nullable;
    
    import org.eclipse.paho.client.mqttv3.MqttClient;
    import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
    import org.eclipse.paho.client.mqttv3.MqttException;
    import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
    
    
    public class MQTTService extends Service {
        private static final String TAG = "MQTTService";
        public static final String BROKER_URL = "tcp://你自己的MQTT服务器的ip:1883";
        public static final String CLIENT_ID = "gongzhonghaobadaodecehngxvyuan";
    
        public static MqttClient mqttClient;
        //mqtt连接配置
        private MqttConnectOptions mqttOptions;
        private String username = "admin";
        private String password = "admin";
    
        public MQTTService() {
    
        }
    
        @Nullable
        @Override
        public IBinder onBind(Intent intent) {
            return null;
        }
    
        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {
            Log.i(TAG, "onStartCommand: begin");
    
            try {
                //第三个参数代表持久化客户端，如果为null，则不持久化
                mqttClient = new MqttClient(BROKER_URL, CLIENT_ID, new MemoryPersistence());
                //mqtt连接设置
                mqttOptions = new MqttConnectOptions();
                mqttOptions.setUserName(username);
                mqttOptions.setPassword(password.toCharArray());
                //超时连接，单位为秒
                mqttOptions.setConnectionTimeout(10);
                mqttOptions.setKeepAliveInterval(20);
                //false代表可以接受离线消息
                mqttOptions.setCleanSession(false);
                mqttOptions.setAutomaticReconnect(true);
                // 设置回调
                mqttClient.setCallback(new PushCallback(mqttClient));
                Log.i(TAG, "onStartCommand: before connect");
                //客户端下线，其它客户端或者自己再次上线可以接收"遗嘱"消息
    //            MqttTopic topic1 = mqttClient.getTopic(TOPIC);
    //            mqttOptions.setWill(topic1, "close".getBytes(), 2, true);
                mqttClient.connect(mqttOptions);
                Log.i(TAG, "onStartCommand: after connect");
                Log.i(TAG, "连接mqtt服务器成功，可以进行发布消息");
    
            } catch (MqttException e) {
                e.printStackTrace();
                Log.i(TAG, e.getMessage());
            }
            return super.onStartCommand(intent, flags, startId);
        }
    
        @Override
        public void onDestroy() {
            try {
                mqttClient.disconnect();
            } catch (MqttException e) {
                e.printStackTrace();
            }
        }
    }

注意这里的mqtt服务器的url改为你自己的ip和端口号，以及自己的用户名和密码，获取方式可以参照上面博客。

新建完service后要在AndroidManifest中声明service

在service中设置了回调方法，用来处理形如连接成功、收到消息、发送消息成功等的回调。

所以需要新建一个回调方法类PushCallback

package com.badao.androidmqttpublishclient.mqtt;
    
    import android.util.Log;
    
    import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
    import org.eclipse.paho.client.mqttv3.MqttCallbackExtended;
    import org.eclipse.paho.client.mqttv3.MqttClient;
    import org.eclipse.paho.client.mqttv3.MqttMessage;
    
    
    public class PushCallback implements MqttCallbackExtended {
        private static final String TAG = "PusherCallback";
        private MqttClient mqttClient = null;
    
        public PushCallback(MqttClient client) {
            mqttClient = client;
        }
    
        @Override
        public void connectionLost(Throwable cause) {
            Log.i(TAG, "连接失败");
        }
    
        @Override
        public void messageArrived(String topic, MqttMessage message) throws Exception {
            String msg = new String(message.getPayload());
            Log.i(TAG, "消息到达,message: " + msg);
    
        }
    
        @Override
        public void deliveryComplete(IMqttDeliveryToken token) {
            Log.i(TAG, "消息成功发送");
    
        }
    
        @Override
        public void connectComplete(boolean reconnect, String serverURI) {
            Log.i(TAG, "连接完成");
    
        }
    }

根据自己的需要重写一些回调方法。

然后就是在MainActivity中的onCreate方法中启动服务，用来在启动后实现连接到mqtt服务器等操作。

@Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //启动服务
            Intent intent = new Intent(this, MQTTService.class);
            startService(intent);
        }

为了实现推送消息，在主页面添加一个按钮

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    
        <Button
            android:id="@+id/publishButton"
            android:text="发布消息"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    
    </RelativeLayout>

然后在activity中设置按钮的点击事件

Button publishButton = findViewById(R.id.publishButton);
            publishButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
    
                    //在mqtt中用QoS来标识服务质量
                    //QoS=0时，报文最多发送一次，有可能丢失
                    //QoS=1时，报文至少发送一次，有可能重复
                    //QoS=2时，报文只发送一次，并且确保消息只到达一次。
                    MqttMessage mqttMessage = new MqttMessage();
                    mqttMessage.setId((int) Math.random());
                    mqttMessage.setQos(1);
                    mqttMessage.setPayload("这是来自APP发布的消息：公众号-霸道的程序猿".getBytes());
                    /*当设置Retain标识位的时候，该消息即为遗言消息。
                    broker收到该消息后会保存此消息，当有新的订阅者订阅此主题时候，broker会立即发送此消息。
                    有点类似于会话清除，不同的是遗言只有一条，后面的遗言消息会覆盖前面的。
                    如果需要删除retain消息，可以发布一个空的retain消息，因为每个新的retain消息都会覆盖最后一个retain消息*/
                    mqttMessage.setRetained(false);
                    try {
                        MQTTService.mqttClient.publish("badaodechengxvyuan",mqttMessage);
    
                    } catch (MqttException e) {
                        e.printStackTrace();
                    }
                }
            });

在点击事件中，构造一个MqttMessage消息对象，设置其相关参数，主要是通过器payload设置其消息内容。

然后调用service的mqtt客户端的publish方法，第一个参数是主题，第二个参数是消息对象。

然后运行app

可以看到service已经启动成功，并且调用了连接成功的回调方法

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

然后为了收到想通主题的订阅的消息，使用MQTTBox订阅一个同样主题

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

然后在点击主页面的发布消息的按钮，可以看到发送成功的回调方法已经被调用

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

然后在Mqttbox中也已经收到了消息

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

### 示例代码下载 ###

[https://download.csdn.net/download/BADAO\_LIUMANG\_QIZHI/14093918][https_download.csdn.net_download_BADAO_LIUMANG_QIZHI_14093918]

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_112305328]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/112305328
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_112394731]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/112394731
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20210111092121593.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20210111092123760.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[https_download.csdn.net_download_BADAO_LIUMANG_QIZHI_14093918]: https://download.csdn.net/download/BADAO_LIUMANG_QIZHI/14093918