C++ 如何使用具有全局函数c++；（多次定义..和未定义引用失败）-谷歌云IoT Mqtt

我希望你能帮助我：

我正在使用platformIO和ESP32 Wifi模块，并希望通过mqtt实现与谷歌云的连接

首选以下体系结构：

main.cpp---包括-->WifiClass.h---包括-->iot mqtt.h---包括-->CloudIoTCoreMqtt.h

main.cpp包括用于Esp32（如Arduino）的带有setup（）和loop（）的脚本。WifiClass应该是来自Google/Apache的云bib与main.cpp脚本之间的连接。iot mqtt.h包含初始化wifi和mqtt以及数据交换和回调处理程序的方法

我最大的问题是：

iot mqtt.h不包含类，只包含全局函数和变量。当我想将其包含在wifi.h中并开始编译时，我总是会得到带有多个定义的错误。 我不知道将变量标记为extern并在iot-mqtt.cpp文件中定义它们并将函数标记为static是否正确？如果这样做，就会得到一个错误，即回调函数具有未定义的引用，因为它们在CloudIoCoreMqtt中使用

有谁能帮我解决这些问题吗？我没有任何解决的办法

亲切问候,， 弗洛里安

main.cpp：

#include "WifiClass.h"

WifiClass wifiObject;

void setup() {
   wifiObject.begin();
}
void loop() {
  wifiObject.func1();
}

WifiClass.h：

#ifndef __WIFICLASS__
#define __WIFICLASS__

#include "iot-mqtt.h"


class WifiClass {

public:
   void begin();
   void func1();
};
#endif

WifiClass.cpp：

#include "WifiClass.h"

//core functions
void WifiClass::begin()
{
    setupCloudIoT();
}
void WifiClass::func1()
{
    mqttLoop();
}

物联网mqtt.h：（并非所有相关）

/******************************************************************************
 * Copyright 2018 Google
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *****************************************************************************/
// This file contains static methods for API requests using Wifi / MQTT
#ifndef __ESP32_MQTT_H__
#define __ESP32_MQTT_H__

#include <Client.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <NTPClient.h>

#include <MQTT.h>

#include <CloudIoTCore.h>
#include <CloudIoTCoreMqtt.h>
#include "ciotc_config.h" // Update this file with your configuration


// Define NTP Client to get time
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP);

///////////////////////////////

// Initialize WiFi and MQTT for this board
Client *netClient;
CloudIoTCoreDevice *device;
CloudIoTCoreMqtt *mqtt;
MQTTClient *mqttClient;
String jwt;

///////////////////////////////
// Orchestrates various methods from preceeding code.
///////////////////////////////
bool publishTelemetry(String data) {
  return mqtt->publishTelemetry(data);
}

bool publishTelemetry(const char* data, int length) {
  return mqtt->publishTelemetry(data, length);
}

bool publishTelemetry(String subfolder, String data) {
  return mqtt->publishTelemetry(subfolder, data);
}

bool publishTelemetry(String subfolder, const char* data, int length) {
  return mqtt->publishTelemetry(subfolder, data, length);
}

String getWifiStatus() {
  return  String(WiFi.RSSI());
}


// Callback handler for IoT Core messages
void messageReceived(String &topic, String &payload) {
  Serial.println("incoming: " + topic + " - " + payload);
   //payload == UNLOCK;30; => statemachine Start Grill
   //publishTelemetry("");
  String parameters[10];
  parameters[0] = "";
  String parameter = "";
  int i = 0;
  for(char& c : payload) {
    if(c == ';') {
      parameters[i] = parameter;
      parameter = "";
      i++;
    } else {
      parameter += c;
    }
  }

}

String getJwt() {
  iat = time(nullptr);
  Serial.println("Refreshing JWT");
  jwt = device->createJWT(iat, jwt_exp_secs);
  return jwt;
}

void connectRoutine () {
 unsigned long startMillis = millis();
  Serial.println("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print("Current WiFi Status: ");
    Serial.println(WiFi.status());
    if (WiFi.status() == WL_CONNECT_FAILED) {  // WiFi.begin wasn't called yet
      Serial.println("Disconnecting WiFi");
      WiFi.disconnect(true);
     
    } 
    else if (WiFi.status() == WL_NO_SHIELD || WiFi.status() == WL_CONNECTION_LOST)      // WiFi.begin has failed (AUTH_FAIL); 5 - STA_DISCONNECTED
    { 
      Serial.println("Connecting WiFi 2");
      WiFi.mode(WIFI_STA);
      WiFi.begin(ssid, password);
    }
    else if (WiFi.status() == WL_DISCONNECTED)      // WiFi.begin has failed (WL_Disconnectes); 5 - STA_DISCONNECTED
    { 
      if(millis()- startMillis > 2000){
      Serial.println("Reconneting WiFi");
      //WiFi.disconnect(true);
      WiFi.reconnect();
      startMillis = millis();
      }     
    }
    else if (WiFi.status() == WL_NO_SSID_AVAIL)      // SSID not available
    { 
      break;
      }     
    delay(1000);
  }

}

void setupWifi() {
  Serial.println("Starting wifi");
  WiFi.mode(WIFI_STA);
  // WiFi.setSleep(false); // May help with disconnect? Seems to have been removed from WiFi
  WiFi.begin(ssid, password);
  connectRoutine ();
  configTime(0, 0, ntp_primary, ntp_secondary);
  Serial.println("Waiting on time sync...");
  while(!timeClient.update()) {
    timeClient.forceUpdate();
  }
}

void connectWifi() {
  Serial.print("checking wifi reconnect...");
  connectRoutine ();
}

void connect() {
  connectWifi();
  mqtt->mqttConnect();
}

void setupCloudIoT() {
  device = new CloudIoTCoreDevice(
      project_id, location, registry_id, device_id,
      private_key_str);

  setupWifi();
  netClient = new WiFiClientSecure();
  mqttClient = new MQTTClient(512);
  mqttClient->setOptions(180, true, 1000); // keepAlive, cleanSession, timeout
  mqtt = new CloudIoTCoreMqtt(mqttClient, netClient, device);
  mqtt->setUseLts(true);
  mqtt->startMQTT();
}

//IoT Core Functions
void heartBeat() {
  if (millis() - LAST_MILLIS_HEART_BEAT > 10000) {
    LAST_MILLIS_HEART_BEAT = millis();
    //publishTelemetry(mqttClient, "/sensors", getDefaultSensor());
    Serial.println("Sending Device Information: " + getDeviceInformation());
    
    publishTelemetry(getDeviceInformation());
  }
}

void mqttLoop() {
  mqtt->loop();
  delay(10);
  if (!mqttClient->connected()) {
    connect();
  }
}
#endif //__ESP32_MQTT_H__

/******************************************************************************
 * Copyright 2018 Google
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *****************************************************************************/
// This file contains your configuration used to connect to Cloud IoT Core

// Wifi network details.
const char *ssid = "";
const char *password = "";

// Cloud iot details.
const char *project_id = "";
const char *location = "";
const char *registry_id = "";
const char *device_id = "";

// Configuration for NTP
const char* ntp_primary = "";
const char* ntp_secondary = "";

#ifndef LED_BUILTIN
#define LED_BUILTIN 13
#endif

// To get the private key run (where private-key.pem is the ec private key
// used to create the certificate uploaded to google cloud iot):
// openssl ec -in <private-key.pem> -noout -text
// and copy priv: part.
// The key length should be exactly the same as the key length bellow (32 pairs
// of hex digits). If it's bigger and it starts with "00:" delete the "00:". If
// it's smaller add "00:" to the start. If it's too big or too small something
// is probably wrong with your key.
const char *private_key_str ="";

const int jwt_exp_secs = ;
const char *root_cert = "";

/******************************************************************************
 * Copyright 2019 Google
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *****************************************************************************/
#include "CloudIoTCoreMqtt.h"

// Forward global callback declarations
String getJwt();
void setupCert();
Client* setupNetwork(bool);
void messageReceived(String &topic, String &payload);