HarmonyOS 鸿蒙Next ArkTS 使用mqtt创建客户端失败

使用mqtt创建客户端失败，提示mqttAsync为null，如图

操作步骤：

1、安装使用mqtt插件

     使用三方仓库mqtt插件，地址：https://ohpm.openharmony.cn/#/cn/detail/@ohos%2Fmqtt

    安装命令：ohpm i @ohos/mqtt

2、mqtt函数简单封装

在src/main/ets下新建mqtt目录，新建文件MyMqttClient.ets

import { MqttAsync, MqttClient, MqttQos, MqttSubscribeOptions } from ‘@ohos/mqtt’

export class MyMqttClient {
private mqttClient: MqttClient|null=null
public createMqttClient() {
let serverUrl: string =“http://192.168.0.1:18083” //‘你的MQTT服务器地址，例如：tcp://192.168.2.1:1883’
let clientId: string = “clientId_panda” //‘客户端,唯一就行’
if(MqttAsync==undefined){
console.log(“1111111”);
}else{
console.log(“222222222”);
}
// return ;
<span class="hljs-keyword"><span class="hljs-keyword">this</span></span>.mqttClient = MqttAsync.createMqtt({
  url: serverUrl,
  clientId: clientId,
  persistenceType: <span class="hljs-number"><span class="hljs-number">1</span></span>
})
}
public async connectMqtt() {
let result: boolean
// if(this.mqttClient){
//   console.log(“1111111111111”);
// }else {
//   console.log(“2222222222222”);
// }
if(this.mqttClient){
await this.mqttClient.connect({
userName: ‘MQTT用户名’,
password: ‘连接密码’,
connectTimeout: 30,
MQTTVersion: 0
}).then(() => {
result = true
console.info(‘连接成功’)
}).catch(() => {
result = false
console.warn(‘连接失败’)
})
}
}
public async subscribe() {
let subscribeOption: MqttSubscribeOptions = {
topic: ‘你的主题’,
qos: 0
}
if(this.mqttClient){
await this.mqttClient.subscribe(subscribeOption).then((data) => {
console.info(‘MQTT subscribe success ====>’, JSON.stringify(data))
}).catch((err: object) => {
console.error(‘MQTT subscribe failed, Cause:’, JSON.stringify(err))
})
  <span class="hljs-keyword"><span class="hljs-keyword">this</span></span>.mqttClient.messageArrived((err, data) =&gt; {
    <span class="hljs-keyword"><span class="hljs-keyword">if</span></span> (err) {
      console.error(<span class="hljs-string"><span class="hljs-string">'MQTT messageArrived failed, Cause:'</span></span>, <span class="hljs-built_in"><span class="hljs-built_in">JSON</span></span>.stringify(err))
    }<span class="hljs-keyword"><span class="hljs-keyword">else</span></span> {
      console.error(<span class="hljs-string"><span class="hljs-string">'MQTT messageArrived success, 消息内容:'</span></span>, <span class="hljs-built_in"><span class="hljs-built_in">JSON</span></span>.stringify(data))
    }
  })
}
}
public pushMessage(pic: string, mes: string, qo: MqttQos) {
if(this.mqttClient){
this.mqttClient.publish({
topic: pic,
qos: qo,
payload: mes
}, (error, data) => {
if (error) {
console.error(“Push message failed, Cause:”, JSON.stringify(error))
}else {
console.info(“Push message success”, JSON.stringify(data))
}
})
}
}
public destroy() {
if(this.mqttClient){
this.mqttClient.destroy().then((data) => {
console.debug(‘Destroy the mqtt client’, JSON.stringify(data))
})
}
}
}<button style="position: absolute; padding: 4px 8px 0px; cursor: pointer; top: 8px; right: 8px; font-size: 14px;">复制</button>

3、页面按钮调用

在src/mamin/ets/pages下新建Index.ets文件

import { MyMqttClient } from ‘…/mqtt/MyMqttClient’

@Entry
@Component
struct Index {
private myMqttClient?: MyMqttClient
aboutToAppear() {
this.myMqttClient = new MyMqttClient()
}
private createMqtt() {
this.aboutToAppear();
<span class="hljs-keyword"><span class="hljs-keyword">if</span></span>(<span class="hljs-keyword"><span class="hljs-keyword">this</span></span>.myMqttClient){
  <span class="hljs-keyword"><span class="hljs-keyword">this</span></span>.myMqttClient.createMqttClient()
}
}
private connectMqtt() {
if(this.myMqttClient) {
this.myMqttClient.connectMqtt()
}
}
private subTopic() {
if(this.myMqttClient) {
this.myMqttClient.subscribe()
}
}
private pushMessage() {
if(this.myMqttClient) {
this.myMqttClient.pushMessage(‘目标主题’, ‘消息内容’, 0)
}
}
private destroy() {
if(this.myMqttClient) {
this.myMqttClient.destroy()
}
}
build() {
Row() {
Column() {
Button(‘创建MQTT客户端’)
.onClick(() => {
this.createMqtt()
})
Button(‘链接到服务器’)
.onClick(() => {
this.connectMqtt()
})
Button(‘订阅主题’)
.onClick(() => {
this.subTopic()
})
Button(‘发送消息’)
.onClick(() => {
this.pushMessage()
})
Button(‘销毁客户端’)
.onClick(() => {
this.destroy()
})
}
.width(‘100%’)
}
.height(‘100%’)
}
}<button style="position: absolute; padding: 4px 8px 0px; cursor: pointer; top: 8px; right: 8px; font-size: 14px;">复制</button>

4、运行后点击“创建MQTT客户端”按钮报错

错误内容，如第一张图所示。

import mqttAsync from ‘libmqttasync.so’;

此处的mqttAsync为null，导致没有创建成功。

请问是什么原因呢？