HarmonyOS实现MQTT消息监听展示

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

应读者要求，这里贴上源码地址

github: https://github.com/baby7/MqttApplication

gitee(码云): https://gitee.com/baby7/MqttApplication