HarmonyOS实现MQTT消息监听展示-51CTO.COM

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思路

因为harmonyOS暂时没有发现现成的mqtt的js包，所以使用Java进行Mqtt消息的接收，使用JS去定时调用Java接收到消息并展示

首先是JS调用Java，JS FA(Feature Ability)调用Java PA(Particle Ability)有两种方式，Ability和Internal Ability，这里使用的是第一种Ability

然后是Java端的Mqtt消息接收，使用paho的第三方库进行消息接收，页面启动时JS端调用Java端实现Mqtt消息接收开始，使用异步挂起，接收消息并缓存，随后JS端每次调用Java端拿到的都是最新缓存的信息

具体代码

hml页面：

<div class="container"> 
    <div> 
        <text class="title"> 
            {{ title }} 
        </text> 
    </div> 
    <div> 
        <text class="title" onclick="mqttMessage"> 
            开始mqtt 
        </text> 
    </div> 
    <div> 
        <text class="title" onclick="stopMqtt"> 
            停止mqtt 
        </text> 
    </div> 
</div>

JS代码：

const ABILITY_TYPE_EXTERNAL = 0; 
const ACTION_SYNC = 0; 
const ACTION_MESSAGE_CODE_START_MQTT = 1001; 
const ACTION_MESSAGE_CODE_MQTT_MESSAGE = 1002; 
const BUNDLE_NAME = 'com.example.mqttapplication'; 
const ABILITY_NAME = 'com.example.mqttapplication.PlayAbility'; 
 
export const playAbility = { 
    startMqtt: async function() { 
        FeatureAbility.callAbility({ 
            messageCode: ACTION_MESSAGE_CODE_START_MQTT, 
            abilityType: ABILITY_TYPE_EXTERNAL, 
            syncOption: ACTION_SYNC, 
            bundleName: BUNDLE_NAME, 
            abilityName: ABILITY_NAME 
        }); 
    }, 
    mqttMessage: async function(that) { 
        var result = await FeatureAbility.callAbility({ 
            messageCode: ACTION_MESSAGE_CODE_MQTT_MESSAGE, 
            abilityType: ABILITY_TYPE_EXTERNAL, 
            syncOption: ACTION_SYNC, 
            bundleName: BUNDLE_NAME, 
            abilityName: ABILITY_NAME 
        }); 
        var ret = JSON.parse(result); 
        if (ret.code == 0) { 
            console.info('mqtt is:' + JSON.stringify(ret.abilityResult)); 
            that.title = 'mqtt is:' + JSON.stringify(ret.abilityResult); 
        } else { 
            console.error('mqtt error code:' + JSON.stringify(ret.code)); 
        } 
    } 
} 
export default { 
    data: { 
        title: "", 
        timer: null 
    }, 
    task() { 
        playAbility.mqttMessage(this); 
    }, 
    mqttMessage() { 
        this.title = "开始获取MQTT消息"; 
        this.task() 
        this.timer=setInterval(this.task,200) 
    }, 
    stopMqtt() { 
        clearInterval(this.timer) 
    } 
} 
//初始化Java端Mqtt消息接收 
playAbility.startMqtt()

Java端代码(接收Mqtt消息，异步)

import org.eclipse.paho.client.mqttv3.*; 
import org.eclipse.paho.client.mqttv3.MqttMessage; 
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence; 
 
import java.util.List; 
 
 
public class MqttThread implements Runnable { 
 
    /**地址*/ 
    public static final String MQTT_BROKER_HOST = "tcp://xxx.xxx.xxx.xxx:1883"; 
    /**客户端唯一标识*/ 
    public static final String MQTT_CLIENT_ID = "client"; 
    /**订阅标识*/ 
    public static final String MQTT_TOPIC = "HarmonyTest"; 
    /**客户端*/ 
    private volatile static MqttClient mqttClient; 
    /**连接选项*/ 
    private static MqttConnectOptions options; 
    /**消息*/ 
    private final List<String> message; 
 
    public MqttThread(List<String> message) { 
        this.message = message; 
    } 
 
    public void run() { 
        try { 
            mqttClient = new MqttClient(MQTT_BROKER_HOST, MQTT_CLIENT_ID, new MemoryPersistence()); 
            options = new MqttConnectOptions(); 
            options.setCleanSession(true); 
            options.setConnectionTimeout(20); 
            options.setKeepAliveInterval(20); 
            mqttClient.connect(options); 
            mqttClient.subscribe(MQTT_TOPIC); 
            mqttClient.setCallback(new MqttCallback() { 
                @Override 
                public void connectionLost(Throwable throwable) { } 
                @Override 
                public void messageArrived(String s, MqttMessage mqttMessage) { 
                    message.clear(); 
                    message.add(mqttMessage.toString()); 
                    System.out.println("接收到mqtt消息：" + mqttMessage.toString()); 
                } 
                @Override 
                public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) { } 
            }); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
}

Java端代码(Particle Ability)

import com.example.mqttapplication.mqtt.MqttThread; 
import ohos.aafwk.ability.Ability; 
import ohos.aafwk.content.Intent; 
import ohos.hiviewdfx.HiLog; 
import ohos.hiviewdfx.HiLogLabel; 
import ohos.rpc.*; 
import ohos.utils.zson.ZSONObject; 
 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
 
public class PlayAbility extends Ability { 
 
    static final HiLogLabel label = new HiLogLabel(HiLog.LOG_APP, 1, "MY_TAG"); 
 
    private static final int ERROR = -1; 
    private static final int SUCCESS = 0; 
    private static final int START_MQTT = 1001; 
    private static final int MQTT_MESSAGE = 1002; 
 
    @Override 
    protected void onStart(Intent intent) { 
        super.onStart(intent); 
    } 
 
    @Override 
    protected IRemoteObject onConnect(Intent intent) { 
        super.onConnect(intent); 
        PlayRemote remote = new PlayRemote(); 
        return remote.asObject(); 
    } 
 
    static class PlayRemote extends RemoteObject implements IRemoteBroker { 
 
        private List<String> message; 
 
        private Thread thread; 
 
        public PlayRemote() { 
            super("PlayRemote"); 
        } 
 
        @Override 
        public boolean onRemoteRequest(int code, MessageParcel data, MessageParcel reply, MessageOption option) { 
            // 开始mqtt 
            else if (code == START_MQTT) { 
                Map<String, Object> result = new HashMap<>(); 
                result.put("code", SUCCESS); 
                result.put("abilityResult", "成功开始mqtt"); 
                try { 
                    message = new ArrayList<>(); 
                    MqttThread mqttThread = new MqttThread(message); 
                    thread = new Thread(mqttThread); 
                    thread.start(); 
                    System.out.println("mqtt启动成功"); 
                } 
                catch (Exception e) { 
                    result.put("code", ERROR); 
                    result.put("abilityResult", "启动失败"); 
                } 
                reply.writeString(ZSONObject.toZSONString(result)); 
            } 
            // 获取mqtt消息 
            else if (code == MQTT_MESSAGE) { 
                Map<String, Object> result = new HashMap<>(); 
                result.put("code", SUCCESS); 
                if (message.isEmpty()) { 
                    result.put("abilityResult", "未接收到MQTT消息"); 
                } 
                else { 
                    ZSONObject zsonObject = ZSONObject.stringToZSON(message.get(0)); 
                    result.put("abilityResult", zsonObject.getString("message")); 
                } 
                reply.writeString(ZSONObject.toZSONString(result)); 
            } 
            else { 
                Map<String, Object> result = new HashMap<>(); 
                result.put("abilityError", ERROR); 
                reply.writeString(ZSONObject.toZSONString(result)); 
                return false; 
            } 
            return true; 
        } 
 
        @Override 
        public IRemoteObject asObject() { 
            return this; 
        } 
    } 
}

另外启动网络连接还需要往config.json里加点东西获取权限

{ 
  ... 
  "module": { 
    ... 
    "reqPermissions": [ 
      { 
        "name": "ohos.permission.GET_NETWORK_INFO" 
      }, 
      { 
        "name": "ohos.permission.INTERNET" 
      }, 
      { 
        "name": "ohos.permission.SET_NETWORK_INFO" 
      }, 
      { 
        "name": "ohos.permission.MANAGE_WIFI_CONNECTION" 
      }, 
      { 
        "name": "ohos.permission.SET_WIFI_INFO" 
      }, 
      { 
        "name": "ohos.permission.GET_WIFI_INFO" 
      } 
    ] 
  } 
}

最后写了个python的脚本用来发送mqtt消息，很简单就一行

import paho.mqtt.publish as publish 
publish.single('HarmonyTest', '{"message":"BongShakalaka"}', hostname='xxx.xxx.xxx.xxx')

附：mqtt消息是要有mqtt服务器的，这个就自己搭或者买吧

想了解更多内容，请访问：

51CTO和华为官方合作共建的鸿蒙技术社区

https://harmonyos.51cto.com