MQTT的认识（3）- 案例

1. 服务器文件

服务器地址可以参考用 artemis 生成的 myboker 中的broker.xml文件，该文件也是 bootstrap.xml 中标记的服务器文件

<broker xmlns="http://activemq.apache.org/schema">
   <jaas-security domain="activemq"/>
   
   <server configuration="file:/D:/ProgramFiles/apache-artemis-2.26.0-bin/apache-artemis-2.26.0/bin/myboker/etc//broker.xml"/>
   
   <web path="web" rootRedirectLocation="console">
       <binding uri="http://localhost:8161">
           <app url="activemq-branding" war="activemq-branding.war"/>
           <app url="artemis-plugin" war="artemis-plugin.war"/>
           <app url="console" war="console.war"/>
       binding>
   web>


broker>


 <acceptors>
     
     <acceptor name="artemis">tcp://0.0.0.0:61616?tcpSendBufferSize=1048576;tcpReceiveBufferSize=1048576;amqpMinLargeMessageSize=102400;protocols=CORE,AMQP,STOMP,HORNETQ,MQTT,OPENWIRE;useEpoll=true;amqpCredits=1000;amqpLowCredits=300;amqpDuplicateDetection=true;supportAdvisory=false;suppressInternalManagementObjects=falseacceptor>
     
     <acceptor name="amqp">tcp://0.0.0.0:5672?tcpSendBufferSize=1048576;tcpReceiveBufferSize=1048576;protocols=AMQP;useEpoll=true;amqpCredits=1000;amqpLowCredits=300;amqpMinLargeMessageSize=102400;amqpDuplicateDetection=trueacceptor>

     
     <acceptor name="stomp">tcp://0.0.0.0:61613?tcpSendBufferSize=1048576;tcpReceiveBufferSize=1048576;protocols=STOMP;useEpoll=trueacceptor>

     
     <acceptor name="hornetq">tcp://0.0.0.0:5445?anycastPrefix=jms.queue.;multicastPrefix=jms.topic.;protocols=HORNETQ,STOMP;useEpoll=trueacceptor>
     
     <acceptor name="mqtt">tcp://0.0.0.0:1883?tcpSendBufferSize=1048576;tcpReceiveBufferSize=1048576;protocols=MQTT;useEpoll=trueacceptor>

acceptors>
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可以看到上述 mqtt 使用的端口是1883，协议标识符用的都是tcp

2. 配置依赖

1. 按照eclipse/paho.mqtt.android的指导，完成依赖

    repositories {
        maven {
            url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
        }
    }
   
   implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
   implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
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2. AndroidManifest.xml添加相应权限

   <uses-permission android:name="android.permission.INTERNET" />
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
   <uses-permission android:name="android.permission.WAKE_LOCK" />
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3. AndroidManifest.xml注册Service

   <service
       android:name="org.eclipse.paho.android.service.MqttService"
       tools:ignore="MissingClass" /> 
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3. 示例代码

我们以本机为服务器

package com.monk.test

import android.content.Context
import android.net.ConnectivityManager
import android.util.Log
import android.widget.Toast
import com.h3c.client.global.GlobalContext
import org.eclipse.paho.android.service.MqttAndroidClient
import org.eclipse.paho.client.mqttv3.*

/**
 * @since 2022/6/2 19:58
 * @author monk
 */
class MyMqtt {
    private var mqttAndroidClient: MqttAndroidClient
    // 本机ip + mqtt端口号
    private val serverUri = "tcp://10.213.122.137:1883"
    // 其它客户端主题，自己订阅
    private val publishTopic = "home/garden/fountain"
    // 自己主题，其它客户端订阅
    private var responseTopc ="responseTopic"

    private val TAG ="MyMqtt"

    private val mqttConnectOptions = MqttConnectOptions()

    init {
        mqttAndroidClient = MqttAndroidClient(GlobalContext.getContext(), serverUri, "Android")
        mqttAndroidClient.setCallback(object : MqttCallback {
            override fun connectionLost(cause: Throwable?) {
                // 连接断开
//                connect()
                Log.e(TAG,"connectionLost")
            }

            override fun messageArrived(topic: String?, message: MqttMessage?) {
                // 收到消息
                val msg = String(message?.payload!!)
                Toast.makeText(GlobalContext.getContext(), msg, Toast.LENGTH_LONG).show()
                Log.e(TAG, "topic:$topic -- msg:$msg")
                // 响应给对方
                mqttAndroidClient.publish(responseTopc, "I get it!!".toByteArray(), 2, false)
            }

            override fun deliveryComplete(token: IMqttDeliveryToken?) {
                // 消息传递完成并收到所有确认
            }
        })

        // 设置是否清除缓存
        mqttConnectOptions.isCleanSession = true
        mqttConnectOptions.connectionTimeout = 10
        // 心跳包发送间隔
        mqttConnectOptions.keepAliveInterval = 20
        mqttConnectOptions.userName = "monk"
        mqttConnectOptions.password = "123456".toCharArray()

        val message = "{terminal_uid:Android}"
        try {
            mqttConnectOptions.setWill(publishTopic, message.toByteArray(), 2, false)
        } catch (e: Exception) {
            println(e.message)
//            connect()
        }
        connect()
    }

    private fun connect() {
        if (!mqttAndroidClient.isConnected && isConnected()) {
            mqttAndroidClient.connect(mqttConnectOptions, null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    // 订阅主题
                    Log.e(TAG,"onSuccess")
                    mqttAndroidClient.subscribe(publishTopic, 2)
                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    exception?.printStackTrace()
                    Log.e(TAG,"onFailure")
//                    connect()
                }
            })
            Log.e(TAG,"有网络")
        }else{
            Log.e(TAG,"无网络")
        }
    }


    private fun isConnected(): Boolean {
        val cm = GlobalContext.getContext().getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        return cm.activeNetworkInfo != null && (cm.activeNetworkInfo)?.isAvailable!!
    }


    fun disconnect(){
        mqttAndroidClient.disconnect()
    }

}
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简单说明下，mqtt基于发布/订阅模型：

• 订阅：mqttAndroidClient.subscribe(其它客户机主题, qos)
• 发布：mqttAndroidClient.publish(自己主题, "自己发布消息".toByteArray(), qos, false)

通过这种模型，就可以去其它客户端进行 mqtt 通信，客户端分别是mqttfx和大屏设备

1. mqttfx 发布消息，发布主题、消息，发布出去

   

2. 大屏设备接收消息，并且响应给 mqttfx

   

3. mqttfx接收消息

   

由于用的是本机服务器，所以l两个客户端需要处于同一网段，否则无法通信

以上就通过一个案例展示了 mqtt 的通信过程，希望对大家有所帮助