MQTT协议为物联网量身打造!
物联网 (IoT) 设备必须连接互联网。通过连接到互联网,设备就能相互协作,以及与后端服务协同工作。互联网的基础网络协议是 TCP/IP。MQTT(消息队列遥测传输) 是基于 TCP/IP 协议栈而构建的,已成为 IoT 通信的标准。
MQTT 最初由 IBM 于上世纪 90 年代晚期发明和开发。它最初的用途是将石油管道上的传感器与卫星相链接。顾名思义,它是一种支持在各方之间异步通信的消息协议。异步消息协议在空间和时间上将消息发送者与接收者分离,因此可以在不可靠的网络环境中进行扩展。虽然叫做消息队列遥测传输,但它与消息队列毫无关系,而是使用了一个发布和订阅的模型。在 2014 年末,它正式成为了一种 OASIS 开放标准,而且在一些流行的编程语言中受到支持(通过使用多种开源实现)。
为何选择 MQTT
MQTT 是一种轻量级的、灵活的网络协议,致力于为 IoT 开发人员实现适当的平衡:这个轻量级协议可在严重受限的设备硬件和高延迟/带宽有限的网络上实现。它的灵活性使得为 IoT 设备和服务的多样化应用场景提供支持成为可能。
随着MQTT协议越来越常见,自己在手写项目时,有一份安卓开发源码,肯定更加得心应手!
接下来,就带大家剖析一下,安卓手写MQTT调试工具或者将MQTT作为手机终端需要哪些步骤叭!
首先要新建一个工程!废话就不多说了!
重要的文件就是上边用红框框圈起来的四个文件!
作用分别是:
文件 | 作用 |
AndroidManifest.xml | 权限申请 |
MainActivity | 调用MQTT服务实现逻辑 |
MyMqttService | 创建MQTT服务,实现收发函数 |
activity_main.xml | 编写界面 |
- AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.dongeast.mytestsecond">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.Mytestsecond">
<service
android:name=".MyMqttService"
android:enabled="true"
android:exported="true" />
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name="org.eclipse.paho.android.service.MqttService" /> <!-- MqttService <service android:name="com.dongeast.mytestsecond.MyMqttService" />-->
</application>
</manifest>
- MainActivity
package com.dongeast.mytestsecond;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private Button button;
private TextView textView;
int counter = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.text);
button = (Button) findViewById(R.id.button);
MyMqttService.startService(this); //开启服务
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
int order;
counter++;
order = counter%2;
//textView.setText(order);
if(order == 0){
MyMqttService.publish("0");
}
else{
MyMqttService.publish("1");
}
}
});
}
}
- MyMqttService
package com.dongeast.mytestsecond;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Build;
import android.os.Handler;
import android.os.IBinder;
//import android.support.annotation.Nullable;
//import android.support.annotation.RequiresApi;
import android.util.Log;
import android.widget.Toast;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import org.eclipse.paho.android.service.MqttAndroidClient;
import org.eclipse.paho.client.mqttv3.IMqttActionListener;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.IMqttToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
/**
* Author wildma
* Github https://github.com/wildma
* CreateDate 2018/11/08
* Desc ${MQTT服务}
*/
public class MyMqttService extends Service {
public final String TAG = MyMqttService.class.getSimpleName();
private static MqttAndroidClient mqttAndroidClient;
private MqttConnectOptions mMqttConnectOptions;
public String HOST = "tcp://122.14.253.88:20379";//服务器地址(协议+地址+端口号)
public String USERNAME = "admin";//用户名
public String PASSWORD = "public";//密码
public static String PUBLISH_TOPIC = "led";//发布主题
public static String RESPONSE_TOPIC = "AndroidResponse";//响应主题
@RequiresApi(api = 26)
//public String CLIENTID = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
// ? Build.getSerial() : Build.SERIAL;//客户端ID,一般以客户端唯一标识符表示,这里用设备序列号表示
public String CLIENTID = "AndroidId";
@RequiresApi(api = Build.VERSION_CODES.O)
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
init();
return super.onStartCommand(intent, flags, startId);
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
/**
* 开启服务
*/
public static void startService(Context mContext) {
mContext.startService(new Intent(mContext, MyMqttService.class));
}
/**
* 发布 (模拟其他客户端发布消息)
*
* @param message 消息
*/
public static void publish(String message) {
String topic = PUBLISH_TOPIC;
Integer qos = 2;
Boolean retained = false;
try {
//参数分别为:主题、消息的字节数组、服务质量、是否在服务器保留断开连接后的最后一条消息
mqttAndroidClient.publish(topic, message.getBytes(), qos.intValue(), retained.booleanValue());
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 响应 (收到其他客户端的消息后,响应给对方告知消息已到达或者消息有问题等)
*
* @param message 消息
*/
public void response(String message) {
String topic = RESPONSE_TOPIC;
Integer qos = 2;
Boolean retained = false;
try {
//参数分别为:主题、消息的字节数组、服务质量、是否在服务器保留断开连接后的最后一条消息
mqttAndroidClient.publish(topic, message.getBytes(), qos.intValue(), retained.booleanValue());
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 初始化
*/
@RequiresApi(api = Build.VERSION_CODES.O)
private void init() {
String serverURI = HOST; //服务器地址(协议+地址+端口号)
mqttAndroidClient = new MqttAndroidClient(this, serverURI, CLIENTID);
mqttAndroidClient.setCallback(mqttCallback); //设置监听订阅消息的回调
mMqttConnectOptions = new MqttConnectOptions();
mMqttConnectOptions.setCleanSession(true); //设置是否清除缓存
mMqttConnectOptions.setConnectionTimeout(10); //设置超时时间,单位:秒
mMqttConnectOptions.setKeepAliveInterval(20); //设置心跳包发送间隔,单位:秒
mMqttConnectOptions.setUserName(USERNAME); //设置用户名
mMqttConnectOptions.setPassword(PASSWORD.toCharArray()); //设置密码
// last will message
boolean doConnect = true;
String message = "{\"terminal_uid\":\"" + CLIENTID + "\"}";
String topic = PUBLISH_TOPIC;
Integer qos = 2;
Boolean retained = false;
if ((!message.equals("")) || (!topic.equals(""))) {
// 最后的遗嘱
try {
mMqttConnectOptions.setWill(topic, message.getBytes(), qos.intValue(), retained.booleanValue());
} catch (Exception e) {
Log.i(TAG, "Exception Occured", e);
doConnect = false;
iMqttActionListener.onFailure(null, e);
}
}
if (doConnect) {
doClientConnection();
}
}
/**
* 连接MQTT服务器
*/
private void doClientConnection() {
if (!mqttAndroidClient.isConnected() && isConnectIsNomarl()) {
try {
mqttAndroidClient.connect(mMqttConnectOptions, null, iMqttActionListener);
} catch (MqttException e) {
e.printStackTrace();
}
}
}
/**
* 判断网络是否连接
*/
private boolean isConnectIsNomarl() {
ConnectivityManager connectivityManager = (ConnectivityManager) this.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = connectivityManager.getActiveNetworkInfo();
if (info != null && info.isAvailable()) {
String name = info.getTypeName();
Log.i(TAG, "当前网络名称:" + name);
return true;
} else {
Log.i(TAG, "没有可用网络");
/*没有可用网络的时候,延迟3秒再尝试重连*/
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
doClientConnection();
}
}, 3000);
return false;
}
}
//MQTT是否连接成功的监听
private IMqttActionListener iMqttActionListener = new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken arg0) {
Log.i(TAG, "连接成功 ");
try {
mqttAndroidClient.subscribe(PUBLISH_TOPIC, 2);//订阅主题,参数:主题、服务质量
} catch (MqttException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(IMqttToken arg0, Throwable arg1) {
arg1.printStackTrace();
Log.i(TAG, "连接失败 ");
doClientConnection();//连接失败,重连(可关闭服务器进行模拟)
}
};
//订阅主题的回调
private MqttCallback mqttCallback = new MqttCallback() {
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
Log.i(TAG, "收到消息: " + new String(message.getPayload()));
//收到消息,这里弹出Toast表示。如果需要更新UI,可以使用广播或者EventBus进行发送
Toast.makeText(getApplicationContext(), "messageArrived: " + new String(message.getPayload()), Toast.LENGTH_LONG).show();
//收到其他客户端的消息后,响应给对方告知消息已到达或者消息有问题等
response("message arrived");
}
@Override
public void deliveryComplete(IMqttDeliveryToken arg0) {
}
@Override
public void connectionLost(Throwable arg0) {
Log.i(TAG, "连接断开 ");
doClientConnection();//连接断开,重连
}
};
@Override
public void onDestroy() {
try {
mqttAndroidClient.disconnect(); //断开连接
} catch (MqttException e) {
e.printStackTrace();
}
super.onDestroy();
}
}
- activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">
<TextView
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello Mqtt!"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.189" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.66" />
</androidx.constraintlayout.widget.ConstraintLayout>
最后,如果有报错!那就是没有在项目的build配置中添加依赖了。
- build.gradle
repositories {
maven {
url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
}
}
dependencies {
implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
//noinspection GradleCompatible
implementation 'com.android.support:support-v4:4.4.1'
}
这么详细的教程不会有人看不懂叭~~