Java MqttAsyncClient客户端未连接（32104）

我正在Java中使用MqttAsyncClient。下面的代码只是我如何使用它的一部分，当我试图订阅任何主题时，如果我遇到错误，问题就会出现：

客户端未连接（32104）

这是我得到的错误：

[INFO ] 2019-10-12 21:56:37.234 [main] SpManager - Starting the Mqtt Configuration...
[INFO ] 2019-10-12 21:56:37.388 [main] SpManager - The Mqtt protocol has been configured successfully!!!
[INFO ] 2019-10-12 21:56:37.388 [main] SpManager - Conecting to: tcp://0.tcp.ngrok.io:xxxxx Mqtt Server
[INFO ] 2019-10-12 21:56:37.406 [main] SpManager - Connected to the: tcp://0.tcp.ngrok.io:xxxxx Mqtt Server
[INFO ] 2019-10-12 21:56:37.406 [main] SpManager - Subscribe to the Topic: home/Monitoreo/#
[ERROR] 2019-10-12 21:56:37.427 [main] SpManager - An error has happened: Client is not connected (32104)
[ERROR] 2019-10-12 21:56:37.428 [main] SpManager - 
msg Client is not connected
loc Client is not connected

---

最后，我想指出，当我使用MqttClient而不是MqttAsyncClient

时，此代码可以完美地工作。问题是，您没有在订阅之前等待连接完成。这是因为MqttClient会阻止其中的MqttAsyncClient返回一个令牌，该令牌可用于检查操作何时完成

快速修复方法是在连接（）之后插入一个

waitForCompletion（）

---

它真的工作得很完美！！！现在我的问题是，一旦订阅完成，我就无法收到任何已发布的消息。谢谢

[INFO ] 2019-10-12 21:56:37.234 [main] SpManager - Starting the Mqtt Configuration...
[INFO ] 2019-10-12 21:56:37.388 [main] SpManager - The Mqtt protocol has been configured successfully!!!
[INFO ] 2019-10-12 21:56:37.388 [main] SpManager - Conecting to: tcp://0.tcp.ngrok.io:xxxxx Mqtt Server
[INFO ] 2019-10-12 21:56:37.406 [main] SpManager - Connected to the: tcp://0.tcp.ngrok.io:xxxxx Mqtt Server
[INFO ] 2019-10-12 21:56:37.406 [main] SpManager - Subscribe to the Topic: home/Monitoreo/#
[ERROR] 2019-10-12 21:56:37.427 [main] SpManager - An error has happened: Client is not connected (32104)
[ERROR] 2019-10-12 21:56:37.428 [main] SpManager - 
msg Client is not connected
loc Client is not connected

try
{
    logger.info("Connecting to: " + conf.getServerURI() + " Mqtt Server");
    IMqttToken token = client.connect(connOpts);
    token.waitForCompletion();
    logger.info("Connected to the: "+ conf.getServerURI() + " Mqtt Server");
    client.setCallback(getCallback());
    logger.info("Subscribe to the Topic: " + this.topic);
    //Thread.sleep(1000);
    client.subscribe(this.topic, 1);
    logger.info("Successful subscription to topic: " + this.topic);
}
catch(MqttException me)
{

}