esp8266连接mqtt服务器教程。

一、PubSubClient库下载

下载链接：PubSubClient.zip

二、导入项目

#include <ESP8266WiFi.h>
#include "PubSubClient.h"

WiFiClient espwifiClient;
// 初始化mqtt
PubSubClient mqttClient(espwifiClient);

void mqtt_callback(char *topic, byte *payload, unsigned int length) {
  String msg = "";
  for (int i = 0; i < length; i++) {
    msg += (char)payload[i];
  }
  /**
   * 消息处理代码
   */
  msg = "";
}

void setup() {
  Serial.begin(9600);

  WiFi.mode(WIFI_STA);
  // 连接wifi
  WiFi.begin("ssid", "passwd");
  // 等待wifi连接
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }
  Serial.print("wifi connected!");
  // 设置服务器
  mqttClient.setServer("abc.com", 8888);
  // mqtt消息处理
  mqttClient.setCallback(mqtt_callback);
  // 连接mqtt
  mqttClient.connect("id");
}

void loop() {
  // mqtt连接后开启监听
  if (mqttClient.connected()) {
    mqttClient.loop();
  }
}