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在esp32cam中使用 PubSubClient 连接巴法云-MQTT设备云

Winlam
发布日期:2024-01-13 22:25:45

前言

1.了解如何接入的基本知识->4.3 MQTT设备云 2.看不懂没关系,稍微了解下即可.

?成功连接并接收到推送的消息?

21:58:22.594 -> Attempting MQTT connection...connected
21:58:22.692 -> Subscription to 'xxxxx' successful.
21:58:44.312 -> Message arrived [xxxxx] hello
22:00:22.725 -> Message arrived [xxxxx] 12

虽然是在esp32cam中使用,但其他esp版也可以尝试使用.如果可以可以邮我rorinliang076@gmail.com❥(^_-)

实操

1.打开Arduino下载PubSubClient库. 2.PubSubClient引入项目

#include <WiFi.h>
#include <PubSubClient.h>

3.声明配置项

const char* mqtt_server = "bemfa.com";
const int mqtt_server_port = 9501;
#define ID_MQTT "" //你的秘钥
String topic = ""; //你要订阅的主题
WiFiClient espClient;
PubSubClient client(espClient);

4.其他代码

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(ID_MQTT)) {
      Serial.println("connected");
      // 订阅主题 "example/topic"
      if(client.subscribe(topic)) {
        Serial.println("Subscription to '"+topic+"' successful.");
      } else {
        Serial.println("Subscription failed.");
      }
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}
void setup(){
  //order code ...
  client.setServer(mqtt_server,mqtt_server_port);
  client.setCallback(callback);
  if (client.connect(ID_MQTT)) {
    Serial.println("Connected to MQTT server");
    if(client.subscribe("camarados")) {
      Serial.println("Subscription to 'camarados' successful.");
    } else {
      Serial.println("Subscription failed.");
    }
  } else {
    Serial.println("MQTT connection failed");
  }
  //order code ...
}
void loop(){
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

callback(): 这个回调函数将会在客户端收到订阅主题的消息时被调用,可以在这里做一些逻辑判断等操作. reconnect(): 尝试连接到MQTT服务器. 在setup()函数中,通过setServer与setCallback初始化了mqtt链接.并判断是否连接成功,当连接成功时,使用 client.subscribe 订阅主题; 同样的当需要reconnect()的时候,在reconnect()中也进行重新订阅,确保mqtt连接正常.

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