新建安卓项目
第一步
第二步
修改代码
在AndroidManifest.xml文件中添加网络状态，确保连接mqtt服务器！
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
下载mqtt jar包
将Android Studio的文件管理方式修改为项目的方式，将下载好的jar包复制粘贴到app/libs文件夹
然后右键该文件，选择Add as Library
然后将将Android Studio的文件管理方式修改回去即可。
主程序
activity_main.xml
<LinearLayout 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"
android:orientation="vertical"
android:layout_gravity="center"
tools:context=".MainActivity">
<!--添加id就修改layout_gravity、layout_margin布局-->
<TextView
android:id="@+id/test1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:layout_gravity="center"
android:layout_margin="60dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<!--添加button控件及更改布局参数-->
<Button
android:id="@+id/btn0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="vertical"/>
</LinearLayout>
MainActivity.java
注意修改第一行的包名为自己的包名
package com.example.android_mqtt;
import androidx.appcompat.app.AppCompatActivity;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
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.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class MainActivity extends AppCompatActivity {
private String host = "tcp://192.168.3.146:1883";
private String userName = "admin";
private String passWord = "public";
private String mqtt_id="mqttdemo11";
private String mqtt_sub_topic = "123"; //为了保证你不受到别人的消息 哈哈
private String mqtt_pub_topic ="123";
private int i = 1;
private Handler handler;
private MqttClient client;
private MqttConnectOptions options;
private ScheduledExecutorService scheduler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView text1 = findViewById(R.id.test1);
Button btn = findViewById(R.id.btn0);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
i++;
publishmessageplus(mqtt_pub_topic,"第一个客户端发送的信息"+String.valueOf(i));//发布消息plus
btn.setText(String.valueOf(i));
}
});
init();
startReconnect();
handler = new Handler() {
@SuppressLint({"SetTextIl8n", "HandlerLeak"})
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1: //开机校验更新回传
break;
case 2: //反馈回转
break;
case 3: //MQTT收到消息回传
text1.setText(msg.obj.toString());
break;
case 30: //连接失败
Toast.makeText(MainActivity.this,"连接失败",Toast.LENGTH_SHORT).show();
break;
case 31: //连接成功
Toast.makeText(MainActivity.this,"连接成功",Toast.LENGTH_SHORT).show();
try {
//client.subscribe(mqtt_sub_topic,2);//订阅
client.subscribe(mqtt_sub_topic,0);//订阅
} catch (MqttException e) {
e.printStackTrace();
}
publishmessageplus(mqtt_pub_topic,"第一个客户端发送的信息");//发布消息plus
break;
default:
break;
}
}
};
}
private void init() {
try {
//host为主机名，test为clientid即连接MQTT的客户端ID，一般以客户端唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存
client = new MqttClient(host, mqtt_id,
new MemoryPersistence());
//MQTT的连接设置
options = new MqttConnectOptions();
//设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接
options.setCleanSession(true);
//设置连接的用户名
options.setUserName(userName);
//设置连接的密码
options.setPassword(passWord.toCharArray());
// 设置超时时间 单位为秒
options.setConnectionTimeout(10);
// 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
options.setKeepAliveInterval(20);
//设置回调
client.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
//连接丢失后，一般在这里面进行重连
System.out.println("connectionLost----------");
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
//publish后会执行到这里
System.out.println("deliveryComplete---------"
+ token.isComplete());
}
@Override
public void messageArrived(String topicName, MqttMessage message)
throws Exception {
//subscribe后得到的消息会执行到这里面
System.out.println("messageArrived----------");
Message msg = new Message();
msg.what = 3;
msg.obj = topicName + "---" + message.toString();
handler.sendMessage(msg);
}
});
} catch (Exception e) {
e.printStackTrace();
}
}
private void Mqtt_connect() {
new Thread(new Runnable() {
@Override
public void run() {
try {
if (!(client.isConnected())){
client.connect(options);
Message msg = new Message();
msg.what=31;
handler.sendMessage(msg);
}
} catch (Exception e) {
e.printStackTrace();
Message msg = new Message();
msg.what = 30;
handler.sendMessage(msg);
}
}
}).start();
}
private void startReconnect() {
scheduler = Executors.newSingleThreadScheduledExecutor();
scheduler.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
if (!client.isConnected()) {
Mqtt_connect();
}
}
}, 0 * 1000, 10 * 1000, TimeUnit.MILLISECONDS);
}
private void publishmessageplus(String topic,String message2)
{
if (client == null || !client.isConnected()) {
return;
}
MqttMessage message = new MqttMessage();
message.setPayload(message2.getBytes());
try {
client.publish(topic,message);
} catch (MqttException e) {
e.printStackTrace();
}
}
}
连接MQTT服务器
搭建本地MQtt服务器参考教程：https://www.cnblogs.com/yecss/p/17832727.html
将此处的地址修改为本机的ip地址加端口号，如果是使用的emqx的在线服务器可用修改为下面这种形式
wss://xxxx:8084
测试结果
APP
云平台
