最后,我们需要检查连接状态,以确保客户端已成功连接到 MQTT 服务器。以下是检查连接状态的代码示例: publicvoidcheckConnection(){try{if(client.isConnected()){System.out.println("Connected to MQTT server");}else{System.out.println("Not connected to MQTT server");}}catch(MqttExceptionme){me.printStackT...
client = connect_mqtt() # 返回一个链接:使用函数on_connect(client, userdata, flags, rc)链接服务器,client.connect(broker, port) client.loop_start() publish(client)# 发送消息:client.publish(topic_publish, **, qos=2, retain=False) 1. 2. 3. 一部分是请求的接受并处理 client.on_message=on_...
System.out.println("mqttClient is not connect"); } }else { System.out.println("mqttClient is null"); } } //重新连接MQTT服务器 public void reConnect() { if(null != mqttClient) { if(!mqttClient.isConnected()) { if(null != mqttConnectOptions) { try { mqttClient.connect(mqttConnect...
System.out.println("mqttClient is not connect"); } }else{ System.out.println("mqttClient is null"); } }//发布消息publicvoidpublishMessage(String pubTopic,String message) {if(null!= mqttClient&&mqttClient.isConnected()) { System.out.println("发布消息 "+mqttClient.isConnected()); System....
http://log.info("接收消息回调: 接收消息内容 : " + new String(mqttMessage.getPayload()));*/ } 已经设置了自动重连功能 options.setAutomaticReconnect(true); 在进行重连时过了几秒就报错 已断开连接 (32109) - java.io.EOFException atorg.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsRec...
REASON_CODE_CLIENT_ALREADY_CONNECTED32100 The client is already connected. REASON_CODE_CLIENT_ALREADY_DISCONNECTED32101 The client is already disconnected. REASON_CODE_CLIENT_DISCONNECT_PROHIBITED32107 Thrown when an attempt to callMqttClient.disconnecthas been made from within a method onMqttCallback. ...
mqttClient.connect(options); subscribe(); }catch(Exception e) { LogUtils.error(logger, e); } LogUtils.info(logger,"startClient() isConnected:" +mqttClient.isConnected()); } 3、订阅主题 订阅主题发生在服务器连接登陆成功之后,这里主要有两点,发布消息的服务质量、以及订阅的主题信息。
if( mqttClient.isConnected() ) { return true; } } catch (MqttException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } return false; } /** * 客户端连接 * @return */ public void connect(){ ...
如题所示，我们有的时候直接使用左连接查询，当右表不存在该数据的时候，是可以查出带有null的列。可是...
在java上试图使用org.eclipse.paho.client.mqttv3连接连接本地部署的emq,emqx服务端的认证配置如下 内置数据库Password-Based, 密码加密方式为plain, 加盐方式为disable使用"emqx_test"作为用户名,使用"emqx_test_password"作为密码。测试连接时,总是连接失败,提示如下异常 org.eclipse.paho.client.mqttv3.MqttSecurityEx...