如何避免订阅同一主题并在HiveMQ Android客户端中多次触发回调？ 预期行为

我想有一个回拨，以听取我订阅的每一个主题，每发送一封邮件只有一次。我的意思是，我想订阅一个主题1000次，但当收到一条消息时，我只想听一次

IDK如果有什么我做错了（我猜）

实际行为

• 我正在开发一个家庭安全摄像头应用程序
• 我有一张我自己的相机清单
• 对于列表中的每一台相机，我都订阅一个主题
• 每隔30秒，我会更新屏幕，然后再次为每台相机订阅一个主题。这意味着一个主题可以订阅多次
• 每次我收到一条关于某个主题的消息时，回调都会触发关于同一主题被订阅多少次的消息

复制 台阶

有一个主题摄像头/123

使用以下名为subscribeWith的方法订阅主题N次

通过摄像头/123发送信息

您将收到N次消息，因为您订阅了N次主题

复制器代码 只是变量

private var mqtt: Mqtt5AsyncClient? = null
private var username: String? = null
private var password: String? = null
private val serverHost: String,
private val serverPort: Int = 1883

构建MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

连接MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

然后订阅一个主题 每次我订阅一个主题，我都会使用这些有趣的方法

fun subscribeWith(topic: String) {
        mqtt?.subscribeWith()
                ?.topicFilter(topic)
                ?.qos(MqttQos.AT_MOST_ONCE)
               ?.callback { t -> onConsumingTopic(t) }  <- I THINK THIS IS THE IMPORTANT THING
                ?.send()
                ?.whenComplete { ack, error -> onTopicConnected(ack, error, topic) }

    }

fun subscribeth（主题：字符串）{
mqtt？.subscribowith（）
？主题过滤器（主题）
？qos（MqttQos.最多一次）
？回调{t->onConsumingTopic（t）}onTopicConnected（ack，error，topic）}
}

如评论中所述，目前唯一的解决方案是在MQTT客户端库之外保留已订阅主题的列表，并在订阅新主题之前进行检查。

如评论中所述，目前唯一的解决方案是在MQTT客户机库之外保留一个订阅主题列表，并在订阅新主题之前进行检查。

我找到了正确答案

无需为每个订阅调用注册回调，也无需使用全局数组处理注册的主题，如下所示：

mqtt?.subscribeWith()
    ?.callback { t -> onConsumingTopic(t) }  <- This is not needed

然后您就可以订阅，而无需提供回调

client.subscribeWith().topicFilter("test").qos(MqttQos.AT_LEAST_ONCE).send();

完整示例：

构建MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

连接MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

订阅主题

mqtt?.subscribeWith()
                ?.topicFilter(topic)
                ?.qos(MqttQos.AT_LEAST_ONCE)
                ?.send()
                ?.whenComplete { ack, error -> onTopicSubscribed(ack, error, topic) }

---

我找到了正确的答案

无需为每个订阅调用注册回调，也无需使用全局数组处理注册的主题，如下所示：

mqtt?.subscribeWith()
    ?.callback { t -> onConsumingTopic(t) }  <- This is not needed

然后您就可以订阅，而无需提供回调

client.subscribeWith().topicFilter("test").qos(MqttQos.AT_LEAST_ONCE).send();

完整示例：

构建MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

连接MQTT

private fun build() {
        if (mqtt != null) return

        mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { Timber.d("On Connected") }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()
    }

fun connect(username: String, password: String) {
        build()

        this.username = username
        this.password = password

        mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username("abc")
                ?.password("123".toByteArray())
                ?.applySimpleAuth()
                ?.send()
    }

 mqtt = Mqtt5Client.builder()
                .identifier(identifier())
                .serverHost(serverHost)
                .serverPort(serverPort)
                .automaticReconnect()
                .applyAutomaticReconnect()
                .addConnectedListener { onMQTTConnected(it) }
                .addDisconnectedListener { onMQTTDisconnected(it) }
                .buildAsync()

        mqtt?.publishes(MqttGlobalPublishFilter.SUBSCRIBED) { onConsumingTopic(it) }

mqtt?.connectWith()
                ?.keepAlive(30)
                ?.sessionExpiryInterval(7200)
                ?.cleanStart(false)
                ?.simpleAuth()
                ?.username(context.getString(R.string.mqtt_user))
                ?.password(context.getString(R.string.mqtt_pw).toByteArray())
                ?.applySimpleAuth()
                ?.send()

订阅主题

mqtt?.subscribeWith()
                ?.topicFilter(topic)
                ?.qos(MqttQos.AT_LEAST_ONCE)
                ?.send()
                ?.whenComplete { ack, error -> onTopicSubscribed(ack, error, topic) }

---

多次订阅一个主题有什么意义？您需要保留一个已订阅主题的列表。在添加新主题之前，请检查列表。完全如我所说。多次订阅。想象一下这个。当我们有一个主题a和MQTT，并且您执行MQTT.subscribe（主题=a）MQTT.subscribe（主题=a）MQTT.subscribe（主题=a）时，当接收到消息时，主题会触发3次@Odysseus@hardillb我想了想，但我认为这只是一个解决办法，而不是真正的行为。MQTT说，订阅同一主题意味着替换，而不是重复。谢谢，我认为这不会发生在代理上，而是在客户端添加额外的匹配回调。多次订阅主题有什么意义？您需要保留一个已订阅主题的列表。在添加新主题之前，请检查列表。完全如我所说。多次订阅。想象一下这个。当我们有一个主题a和MQTT，并且您执行MQTT.subscribe（主题=a）MQTT.subscribe（主题=a）MQTT.subscribe（主题=a）时，当接收到消息时，主题会触发3次@Odysseus@hardillb我想了想，但我认为这只是一个解决办法，而不是真正的行为。MQTT说，订阅同一主题意味着替换，而不是重复。谢谢，我认为这不会发生在代理上，而是在客户端添加额外的匹配回调。