在ESP8266上编写代码，以连接到OneNet的MQTT服务器上传dht11模块所监测的数据

下面是一个示例的ESP8266代码，以连接到OneNet的MQTT服务器上传dht11模块所监测的温度和湿度数据：

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

// Replace with your WiFi credentials
const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";

// Replace with your OneNet MQTT Host and Key
const char* mqtt_server = "mqtt.heclouds.com";
const char* mqtt_username = "your_MQTT_Username";
const char* mqtt_password = "your_MQTT_Password";
const char* mqtt_topic = "your_MQTT_Topic";

// Replace with your DHT11 connected pin
#define DHTPIN D1
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  dht.begin();
  delay(100);

  WiFi.begin(ssid, password);
  Serial.println();
  Serial.print("Connecting to WiFi...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected to WiFi: ");
  Serial.println(WiFi.SSID());
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  Serial.println("Connecting to MQTT...");
  while (!client.connected()) {
    if (client.connect("ESP8266Client", mqtt_username, mqtt_password)) {
      Serial.println("MQTT connected!");
    } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
  client.subscribe(mqtt_topic);
}

void loop() {
  delay(2000);
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  String msg = String("{\"datastreams\":[{\"id\":\"temp\",\"datapoints\":[{\"value\":\"") + t + String("\"}]}," +
              "{\"id\":\"humi\",\"datapoints\":[{\"value\":\"") + h + String("\"}]}]}");

  Serial.print("Sending to OneNet: ");
  Serial.println(msg);

  if (!client.connected()) {
    reconnect();
  }

  client.publish(mqtt_topic, (char*)msg.c_str());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.printf("Message arrived [%s]: ", topic);
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

void reconnect() {
  while (!client.connected()) {
    Serial.println("Attempting MQTT connection...");
    if (client.connect("ESP8266Client", mqtt_username, mqtt_password)) {
      Serial.println("MQTT connected!");
      client.subscribe(mqtt_topic);
    } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
}

请注意：在使用该代码之前，您需要进行以下更改：

1. 替换“ssid”和“password”与您的WiFi凭证。
2. 替换“mqtt_server”、“mqtt_username”和“mqtt_password”与您在OneNet上创建的MQTT套餐的相关数据。
3. 替换DHT模块连接的引脚（在示例中为D1）。

该代码将读取DHT11模块的温度和湿度数据，将其打包到指定MQTT主题的消息中，并上传到OneNet。您可以在您的OneNet帐户中查看和分析数据。