Paho C++ Lib 集成：未解决的外部错误
Paho C++ Lib integration: Unresolved external errors
我正在尝试在我自己的 C++ 项目中使用 Paho C++ 库 (Visual Studio 2017)。
我已经按照解释 here 构建并安装了 Paho C 库和 Paho C++ 库。
到目前为止，一切都很好。之后，我在 Visual Studio 2017 年创建了一个新的（空白）C++ 项目，并在项目属性中应用了以下更改：
- 在选项卡 C/C++ / 常规中：
在 "Additional Include Directories" 中，我添加了两个包含路径（来自 paho c 和 paho c++ 安装路径）：
- 在选项卡链接器/常规中：
在 "Additional Library Directories" 中，我添加了 lib 文件夹的路径（来自 paho c 和 paho c++ 安装路径）：
- 在选项卡 Linker/Input 中：
在 "Additional Dependencies" 中，我添加了 paho c 和 paho c++ 库的库名称。
- 此外，我已经将 paho-mqtt3c.dll 复制到我的 C++ 项目的 Debug 文件夹中，并且包含了 topic_publish.cpp 示例文件（作为我的主要文件）。
问题：如果我尝试构建应用程序，我会收到 20 个链接错误。
1>------ Build started: Project: PahoCppLibTest, Configuration: Debug Win32 ------
1>Main.cpp
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setDisconnected referenced in function "public: void __thiscall mqtt::async_client::set_disconnected_handler(class std::function<void __cdecl(class mqtt::properties const &,enum mqtt::ReasonCode)>)" (?set_disconnected_handler@async_client@mqtt@@QAEXV?$function@$$A6AXABVproperties@mqtt@@W4ReasonCode@2@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setCallbacks referenced in function "public: virtual void __thiscall mqtt::async_client::set_callback(class mqtt::callback &)" (?set_callback@async_client@mqtt@@UAEXAAVcallback@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setConnectionLostCallback referenced in function "public: void __thiscall mqtt::async_client::set_connection_lost_handler(class std::function<void __cdecl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)>)" (?set_connection_lost_handler@async_client@mqtt@@QAEXV?$function@$$A6AXABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setMessageArrivedCallback referenced in function "public: void __thiscall mqtt::async_client::set_message_callback(class std::function<void __cdecl(class std::shared_ptr<class mqtt::message const >)>)" (?set_message_callback@async_client@mqtt@@QAEXV?$function@$$A6AXV?$shared_ptr@$$CBVmessage@mqtt@@@std@@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setConnected referenced in function "public: virtual void __thiscall mqtt::async_client::set_callback(class mqtt::callback &)" (?set_callback@async_client@mqtt@@UAEXAAVcallback@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_reconnect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::reconnect(void)" (?reconnect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@XZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_createWithOptions referenced in function "public: __thiscall mqtt::async_client::async_client(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0async_client@mqtt@@QAE@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@0H0@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_connect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::connect(class mqtt::connect_options)" (?connect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@Vconnect_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_disconnect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::disconnect(class mqtt::disconnect_options)" (?disconnect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@Vdisconnect_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_isConnected referenced in function "public: virtual bool __thiscall mqtt::async_client::is_connected(void)const " (?is_connected@async_client@mqtt@@UBE_NXZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_subscribe referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::subscribe(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,int,class mqtt::subscribe_options const &)" (?subscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@HABVsubscribe_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_subscribeMany referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::subscribe(class std::shared_ptr<class mqtt::string_collection const >,class std::vector<int,class std::allocator<int> > const &,class std::vector<class mqtt::subscribe_options,class std::allocator<class mqtt::subscribe_options> > const &)" (?subscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@V?$shared_ptr@$$CBVstring_collection@mqtt@@@4@ABV?$vector@HV?$allocator@H@std@@@4@ABV?$vector@Vsubscribe_options@mqtt@@V?$allocator@Vsubscribe_options@mqtt@@@std@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_unsubscribe referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::unsubscribe(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?unsubscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_unsubscribeMany referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::unsubscribe(class std::shared_ptr<class mqtt::string_collection const >)" (?unsubscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@V?$shared_ptr@$$CBVstring_collection@mqtt@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_sendMessage referenced in function "public: virtual class std::shared_ptr<class mqtt::delivery_token> __thiscall mqtt::async_client::publish(class std::shared_ptr<class mqtt::message const >)" (?publish@async_client@mqtt@@UAE?AV?$shared_ptr@Vdelivery_token@mqtt@@@std@@V?$shared_ptr@$$CBVmessage@mqtt@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_freeMessage referenced in function "private: static int __cdecl mqtt::async_client::on_message_arrived(void *,char *,int,struct MQTTAsync_message *)" (?on_message_arrived@async_client@mqtt@@CAHPAXPADHPAUMQTTAsync_message@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_free referenced in function "private: static int __cdecl mqtt::async_client::on_message_arrived(void *,char *,int,struct MQTTAsync_message *)" (?on_message_arrived@async_client@mqtt@@CAHPAXPADHPAUMQTTAsync_message@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_destroy referenced in function "public: virtual __thiscall mqtt::async_client::~async_client(void)" (??1async_client@mqtt@@UAE@XZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_strerror referenced in function "public: static class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl mqtt::exception::error_str(int)" (?error_str@exception@mqtt@@SA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z)
1>C:\mqtt\projects\PahoCppLibTest\Debug\PahoCppLibTest.exe : fatal error LNK1120: 19 unresolved externals
1>Done building project "PahoCppLibTest.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
编辑：
该库通过包含它来使用，如下所示：
#include "mqtt/async_client.h"
这是我使用的主要代码（它是来自 paho c++ 库的 "topic_publish.cpp" 示例）：
// topic_publish.cpp
//
// This is a Paho MQTT C++ client, sample application.
//
// It's an example of how to send messages as an MQTT publisher using the
// C++ asynchronous client interface using a 'topic' object to repeatedly
// send data to the same topic.
//
// The sample demonstrates:
// - Connecting to an MQTT server/broker
// - Publishing messages
// - Use of the 'topic' class
//
/*******************************************************************************
* Copyright (c) 2019 Frank Pagliughi <fpagliughi@mindspring.com>
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Frank Pagliughi - initial implementation and documentation
*******************************************************************************/
#include <iostream>
#include <cstdlib>
#include <string>
#include <thread> // For sleep
#include <atomic>
#include <chrono>
#include <cstring>
#include "mqtt/async_client.h"
using namespace std;
const string DFLT_SERVER_ADDRESS{ "tcp://localhost:1883" };
const string TOPIC{ "test" };
const int QOS = 1;
const char* PAYLOADS[] = {
"Hello World!",
"Hi there!",
"Is anyone listening?",
"Someone is always listening.",
nullptr
};
const auto TIMEOUT = std::chrono::seconds(10);
/////////////////////////////////////////////////////////////////////////////
int main(int argc, char* argv[])
{
string address = (argc > 1) ? string(argv[1]) : DFLT_SERVER_ADDRESS;
cout << "Initializing for server '" << address << "'..." << endl;
mqtt::async_client cli(address, "");
cout << " ...OK" << endl;
try {
cout << "\nConnecting..." << endl;
cli.connect()->wait();
cout << " ...OK" << endl;
cout << "\nPublishing messages..." << endl;
mqtt::topic top(cli, "test", QOS);
mqtt::token_ptr tok;
size_t i = 0;
while (PAYLOADS[i]) {
tok = top.publish(PAYLOADS[i++]);
}
tok->wait(); // Just wait for the last one to complete.
cout << "OK" << endl;
// Disconnect
cout << "\nDisconnecting..." << endl;
cli.disconnect()->wait();
cout << " ...OK" << endl;
}
catch (const mqtt::exception& exc) {
cerr << exc.what() << endl;
return 1;
}
return 0;
}
我认为问题出在 paho-mqttpp3-static.lib 文件中，但我不知道如何解决这个问题。有什么建议吗？
它终于按照 fpagliughi (github) 的回答工作了：
Yes, apologies. The build for this library is rather confusing.
Hopefully the next update will make it easier.
Part of the problem is that it requires the separate Paho C library
and that one produces four different versions: two synchronous
versions (secure and unsecure) and two asynchronous versions (also
secure and unsecure).
We only need one of the asynchronous versions: paho-mqtt3a.dll (no
secure sockets) paho-mqtt3as.dll (includes SSL/TLS secure sockets)
So, for your project, try removing 'paho-mqtt3c.dll' and replacing it
with 'paho-mqtt3a.dll'
我正在尝试在我自己的 C++ 项目中使用 Paho C++ 库 (Visual Studio 2017)。 我已经按照解释 here 构建并安装了 Paho C 库和 Paho C++ 库。 到目前为止，一切都很好。之后，我在 Visual Studio 2017 年创建了一个新的（空白）C++ 项目，并在项目属性中应用了以下更改：
- 在选项卡 C/C++ / 常规中： 在 "Additional Include Directories" 中，我添加了两个包含路径（来自 paho c 和 paho c++ 安装路径）：
- 在选项卡链接器/常规中： 在 "Additional Library Directories" 中，我添加了 lib 文件夹的路径（来自 paho c 和 paho c++ 安装路径）：
- 在选项卡 Linker/Input 中： 在 "Additional Dependencies" 中，我添加了 paho c 和 paho c++ 库的库名称。
- 此外，我已经将 paho-mqtt3c.dll 复制到我的 C++ 项目的 Debug 文件夹中，并且包含了 topic_publish.cpp 示例文件（作为我的主要文件）。
问题：如果我尝试构建应用程序，我会收到 20 个链接错误。
1>------ Build started: Project: PahoCppLibTest, Configuration: Debug Win32 ------
1>Main.cpp
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setDisconnected referenced in function "public: void __thiscall mqtt::async_client::set_disconnected_handler(class std::function<void __cdecl(class mqtt::properties const &,enum mqtt::ReasonCode)>)" (?set_disconnected_handler@async_client@mqtt@@QAEXV?$function@$$A6AXABVproperties@mqtt@@W4ReasonCode@2@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setCallbacks referenced in function "public: virtual void __thiscall mqtt::async_client::set_callback(class mqtt::callback &)" (?set_callback@async_client@mqtt@@UAEXAAVcallback@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setConnectionLostCallback referenced in function "public: void __thiscall mqtt::async_client::set_connection_lost_handler(class std::function<void __cdecl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)>)" (?set_connection_lost_handler@async_client@mqtt@@QAEXV?$function@$$A6AXABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setMessageArrivedCallback referenced in function "public: void __thiscall mqtt::async_client::set_message_callback(class std::function<void __cdecl(class std::shared_ptr<class mqtt::message const >)>)" (?set_message_callback@async_client@mqtt@@QAEXV?$function@$$A6AXV?$shared_ptr@$$CBVmessage@mqtt@@@std@@@Z@std@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_setConnected referenced in function "public: virtual void __thiscall mqtt::async_client::set_callback(class mqtt::callback &)" (?set_callback@async_client@mqtt@@UAEXAAVcallback@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_reconnect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::reconnect(void)" (?reconnect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@XZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_createWithOptions referenced in function "public: __thiscall mqtt::async_client::async_client(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0async_client@mqtt@@QAE@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@0H0@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_connect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::connect(class mqtt::connect_options)" (?connect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@Vconnect_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_disconnect referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::disconnect(class mqtt::disconnect_options)" (?disconnect@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@Vdisconnect_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_isConnected referenced in function "public: virtual bool __thiscall mqtt::async_client::is_connected(void)const " (?is_connected@async_client@mqtt@@UBE_NXZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_subscribe referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::subscribe(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,int,class mqtt::subscribe_options const &)" (?subscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@HABVsubscribe_options@2@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_subscribeMany referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::subscribe(class std::shared_ptr<class mqtt::string_collection const >,class std::vector<int,class std::allocator<int> > const &,class std::vector<class mqtt::subscribe_options,class std::allocator<class mqtt::subscribe_options> > const &)" (?subscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@V?$shared_ptr@$$CBVstring_collection@mqtt@@@4@ABV?$vector@HV?$allocator@H@std@@@4@ABV?$vector@Vsubscribe_options@mqtt@@V?$allocator@Vsubscribe_options@mqtt@@@std@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_unsubscribe referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::unsubscribe(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?unsubscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_unsubscribeMany referenced in function "public: virtual class std::shared_ptr<class mqtt::token> __thiscall mqtt::async_client::unsubscribe(class std::shared_ptr<class mqtt::string_collection const >)" (?unsubscribe@async_client@mqtt@@UAE?AV?$shared_ptr@Vtoken@mqtt@@@std@@V?$shared_ptr@$$CBVstring_collection@mqtt@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_sendMessage referenced in function "public: virtual class std::shared_ptr<class mqtt::delivery_token> __thiscall mqtt::async_client::publish(class std::shared_ptr<class mqtt::message const >)" (?publish@async_client@mqtt@@UAE?AV?$shared_ptr@Vdelivery_token@mqtt@@@std@@V?$shared_ptr@$$CBVmessage@mqtt@@@4@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_freeMessage referenced in function "private: static int __cdecl mqtt::async_client::on_message_arrived(void *,char *,int,struct MQTTAsync_message *)" (?on_message_arrived@async_client@mqtt@@CAHPAXPADHPAUMQTTAsync_message@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_free referenced in function "private: static int __cdecl mqtt::async_client::on_message_arrived(void *,char *,int,struct MQTTAsync_message *)" (?on_message_arrived@async_client@mqtt@@CAHPAXPADHPAUMQTTAsync_message@@@Z)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_destroy referenced in function "public: virtual __thiscall mqtt::async_client::~async_client(void)" (??1async_client@mqtt@@UAE@XZ)
1>paho-mqttpp3-static.lib(async_client.obj) : error LNK2019: unresolved external symbol _MQTTAsync_strerror referenced in function "public: static class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl mqtt::exception::error_str(int)" (?error_str@exception@mqtt@@SA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z)
1>C:\mqtt\projects\PahoCppLibTest\Debug\PahoCppLibTest.exe : fatal error LNK1120: 19 unresolved externals
1>Done building project "PahoCppLibTest.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
编辑： 该库通过包含它来使用，如下所示：
#include "mqtt/async_client.h"
这是我使用的主要代码（它是来自 paho c++ 库的 "topic_publish.cpp" 示例）：
// topic_publish.cpp
//
// This is a Paho MQTT C++ client, sample application.
//
// It's an example of how to send messages as an MQTT publisher using the
// C++ asynchronous client interface using a 'topic' object to repeatedly
// send data to the same topic.
//
// The sample demonstrates:
// - Connecting to an MQTT server/broker
// - Publishing messages
// - Use of the 'topic' class
//
/*******************************************************************************
* Copyright (c) 2019 Frank Pagliughi <fpagliughi@mindspring.com>
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Frank Pagliughi - initial implementation and documentation
*******************************************************************************/
#include <iostream>
#include <cstdlib>
#include <string>
#include <thread> // For sleep
#include <atomic>
#include <chrono>
#include <cstring>
#include "mqtt/async_client.h"
using namespace std;
const string DFLT_SERVER_ADDRESS{ "tcp://localhost:1883" };
const string TOPIC{ "test" };
const int QOS = 1;
const char* PAYLOADS[] = {
"Hello World!",
"Hi there!",
"Is anyone listening?",
"Someone is always listening.",
nullptr
};
const auto TIMEOUT = std::chrono::seconds(10);
/////////////////////////////////////////////////////////////////////////////
int main(int argc, char* argv[])
{
string address = (argc > 1) ? string(argv[1]) : DFLT_SERVER_ADDRESS;
cout << "Initializing for server '" << address << "'..." << endl;
mqtt::async_client cli(address, "");
cout << " ...OK" << endl;
try {
cout << "\nConnecting..." << endl;
cli.connect()->wait();
cout << " ...OK" << endl;
cout << "\nPublishing messages..." << endl;
mqtt::topic top(cli, "test", QOS);
mqtt::token_ptr tok;
size_t i = 0;
while (PAYLOADS[i]) {
tok = top.publish(PAYLOADS[i++]);
}
tok->wait(); // Just wait for the last one to complete.
cout << "OK" << endl;
// Disconnect
cout << "\nDisconnecting..." << endl;
cli.disconnect()->wait();
cout << " ...OK" << endl;
}
catch (const mqtt::exception& exc) {
cerr << exc.what() << endl;
return 1;
}
return 0;
}
我认为问题出在 paho-mqttpp3-static.lib 文件中，但我不知道如何解决这个问题。有什么建议吗？
它终于按照 fpagliughi (github) 的回答工作了：
Yes, apologies. The build for this library is rather confusing. Hopefully the next update will make it easier.
Part of the problem is that it requires the separate Paho C library and that one produces four different versions: two synchronous versions (secure and unsecure) and two asynchronous versions (also secure and unsecure).
We only need one of the asynchronous versions: paho-mqtt3a.dll (no secure sockets) paho-mqtt3as.dll (includes SSL/TLS secure sockets)
So, for your project, try removing 'paho-mqtt3c.dll' and replacing it with 'paho-mqtt3a.dll'