在androidx使用mqtt

在Androidx中使用MQTT需要以下步骤：

1. 添加MQTT库依赖：

dependencies {
    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.5'
}

2. 创建MQTT客户端：

val clientId = MqttClient.generateClientId()
val client = MqttAndroidClient(context, serverUri, clientId)
client.setCallback(object : MqttCallbackExtended {
    override fun connectComplete(reconnect: Boolean, serverURI: String) {
        // 连接成功回调
    }

    override fun connectionLost(cause: Throwable?) {
        // 连接断开回调
    }

    override fun messageArrived(topic: String?, message: MqttMessage?) {
        // 收到消息回调
    }

    override fun deliveryComplete(token: IMqttDeliveryToken?) {
        // 发送消息完成回调
    }
})

3. 连接MQTT服务器：

val options = MqttConnectOptions()
options.userName = username
options.password = password.toCharArray()
client.connect(options, null, object : IMqttActionListener {
    override fun onSuccess(asyncActionToken: IMqttToken?) {
        // 连接成功回调
    }

    override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
        // 连接失败回调
    }
})

4. 发布消息：

val message = MqttMessage(payload.toByteArray())
message.qos = qos
client.publish(topic, message, null, object : IMqttActionListener {
    override fun onSuccess(asyncActionToken: IMqttToken?) {
        // 发布成功回调
    }

    override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
        // 发布失败回调
    }
})

5. 订阅主题：

client.subscribe(topic, qos, null, object : IMqttActionListener {
    override fun onSuccess(asyncActionToken: IMqttToken?) {
        // 订阅成功回调
    }

    override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
        // 订阅失败回调
    }
})

6. 取消订阅：

client.unsubscribe(topic, null, object : IMqttActionListener {
    override fun onSuccess(asyncActionToken: IMqttToken?) {
        // 取消订阅成功回调
    }

    override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
        // 取消订阅失败回调
    }
})

7. 断开MQTT连接：

client.disconnect(null, object : IMqttActionListener {
    override fun onSuccess(asyncActionToken: IMqttToken?) {
        // 断开连接成功回调
    }

    override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
        // 断开连接失败回调
    }
})