Link Paho MQTT CMake
Link Paho MQTT CMake
我正在尝试编译一个使用 PAHO-MQTT 的简单测试应用程序。 我正在运行Antergos Linux x64。我无法编译我的项目，因为 PAHO 文件未链接，我不知道如何正确链接它们。 这是我正在尝试编译的主要.cpp。
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "src/MQTTAsync.h"
#include "unistd.h"
#define PUBLISHER 0
volatile MQTTAsync_token deliveredtoken;
int finished = 0;
#if PUBLISHER
#define ADDRESS "tcp://192.168.2.118:1883"
#define CLIENTID "Publisher"
#define TOPIC "test/topic"
#define PAYLOAD "Hello World!"
#define QOS 1
#define TIMEOUT 10000L
void connlost(void *context, char *cause)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
int rc;
printf("nConnection lostn");
printf(" cause: %sn", cause);
printf("Reconnectingn");
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start connect, return code %dn", rc);
finished = 1;
}
}
void onDisconnect(void* context, MQTTAsync_successData* response)
{
printf("Successful disconnectionn");
finished = 1;
}
void onSend(void* context, MQTTAsync_successData* response)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_disconnectOptions opts = MQTTAsync_disconnectOptions_initializer;
int rc;
printf("Message with token value %d delivery confirmedn", response->token);
opts.onSuccess = onDisconnect;
opts.context = client;
if ((rc = MQTTAsync_disconnect(client, &opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start sendMessage, return code %dn", rc);
exit(-1);
}
}
void onConnectFailure(void* context, MQTTAsync_failureData* response)
{
printf("Connect failed, rc %dn", response ? response->code : 0);
finished = 1;
}
void onConnect(void* context, MQTTAsync_successData* response)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
int rc;
printf("Successful connectionn");
opts.onSuccess = onSend;
opts.context = client;
pubmsg.payload = (void *) PAYLOAD;
pubmsg.payloadlen = strlen(PAYLOAD);
pubmsg.qos = QOS;
pubmsg.retained = 0;
deliveredtoken = 0;
if ((rc = MQTTAsync_sendMessage(client, TOPIC, &pubmsg, &opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start sendMessage, return code %dn", rc);
exit(-1);
}
}
int main(int argc, char* argv[])
{
MQTTAsync client;
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
MQTTAsync_token token;
int rc;
MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
MQTTAsync_setCallbacks(client, NULL, connlost, NULL, NULL);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
conn_opts.onSuccess = onConnect;
conn_opts.onFailure = onConnectFailure;
conn_opts.context = client;
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start connect, return code %dn", rc);
exit(-1);
}
printf("Waiting for publication of %sn"
"on topic %s for client with ClientID: %sn",
PAYLOAD, TOPIC, CLIENTID);
while (!finished)
#if defined(WIN32) || defined(WIN64)
Sleep(100);
#else
usleep(10000L);
#endif
MQTTAsync_destroy(&client);
return rc;
}
#elif PUBLISHER == 0
#define ADDRESS "tcp://192.168.2.118:1883"
#define CLIENTID "Subscriber"
#define TOPIC "test/topic"
#define PAYLOAD "Hello World!"
#define QOS 1
#define TIMEOUT 10000L
int disc_finished = 0;
int subscribed = 0;
void connlost(void *context, char *cause) {
MQTTAsync client = (MQTTAsync) context;
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
int rc;
printf("nConnection lostn");
printf(" cause: %sn", cause);
printf("Reconnectingn");
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS) {
printf("Failed to start connect, return code %dn", rc);
finished = 1;
}
}
int msgarrvd(void *context, char *topicName, int topicLen, MQTTAsync_message *message) {
int i;
char *payloadptr;
printf("Message arrivedn");
printf(" topic: %sn", topicName);
printf(" message: ");
payloadptr = (char *) message->payload;
for (i = 0; i < message->payloadlen; i++) {
putchar(*payloadptr++);
}
putchar('n');
MQTTAsync_freeMessage(&message);
MQTTAsync_free(topicName);
return 1;
}
void onDisconnect(void *context, MQTTAsync_successData *response) {
printf("Successful disconnectionn");
disc_finished = 1;
}
void onSubscribe(void *context, MQTTAsync_successData *response) {
printf("Subscribe succeededn");
subscribed = 1;
}
void onSubscribeFailure(void *context, MQTTAsync_failureData *response) {
printf("Subscribe failed, rc %dn", response ? response->code : 0);
finished = 1;
}
void onConnectFailure(void *context, MQTTAsync_failureData *response) {
printf("Connect failed, rc %dn", response ? response->code : 0);
finished = 1;
}
void onConnect(void *context, MQTTAsync_successData *response) {
MQTTAsync client = (MQTTAsync) context;
MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
int rc;
printf("Successful connectionn");
printf("Subscribing to topic %snfor client %s using QoS%dnn"
"Press Q<Enter> to quitnn", TOPIC, CLIENTID, QOS);
opts.onSuccess = onSubscribe;
opts.onFailure = onSubscribeFailure;
opts.context = client;
deliveredtoken = 0;
if ((rc = MQTTAsync_subscribe(client, TOPIC, QOS, &opts)) != MQTTASYNC_SUCCESS) {
printf("Failed to start subscribe, return code %dn", rc);
exit(-1);
}
}
int main(int argc, char *argv[]) {
MQTTAsync client;
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
MQTTAsync_token token;
int rc;
int ch;
MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
MQTTAsync_setCallbacks(client, NULL, connlost, msgarrvd, NULL);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
conn_opts.onSuccess = onConnect;
conn_opts.onFailure = onConnectFailure;
conn_opts.context = client;
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS) {
printf("Failed to start connect, return code %dn", rc);
exit(-1);
}
while (!subscribed)
#if defined(WIN32) || defined(WIN64)
Sleep(100);
#else
usleep(10000L);
#endif
if (finished)
goto exit;
do {
ch = getchar();
} while (ch != 'Q' && ch != 'q');
disc_opts.onSuccess = onDisconnect;
if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS) {
printf("Failed to start disconnect, return code %dn", rc);
exit(-1);
}
while (!disc_finished)
#if defined(WIN32) || defined(WIN64)
Sleep(100);
#else
usleep(10000L);
#endif
exit:
MQTTAsync_destroy(&client);
return rc;
}
#endif
paho mqtt 类位于src目录中。 在我的CMake中，我试图像这样链接它们：
cmake_minimum_required(VERSION 3.10)
project(MQTT)
set(CMAKE_CXX_STANDARD 11)
file(GLOB src "*.h" "*.c")
add_executable(MQTT main.cpp ${src})
尝试编译时提示以下异常：
[ 50%] Linking CXX executable MQTT
CMakeFiles/MQTT.dir/main.cpp.o: In function `connlost(user*, char*)':
/home/user/Documents/Projects/MQTT/main.cpp:161: undefined reference to `MQTTAsync_connect'
CMakeFiles/MQTT.dir/main.cpp.o: In function `msgarrvd(user*, char*, int, MQTTAsync_message*)':
/home/user/Documents/Projects/MQTT/main.cpp:181: undefined reference to `MQTTAsync_freeMessage'
/home/user/Documents/Projects/MQTT/main.cpp:182: undefined reference to `MQTTAsync_free'
CMakeFiles/MQTT.dir/main.cpp.o: In function `onConnect(user*, MQTTAsync_successData*)':
/home/user/Documents/Projects/MQTT/main.cpp:226: undefined reference to `MQTTAsync_subscribe'
CMakeFiles/MQTT.dir/main.cpp.o: In function `main':
/home/user/Documents/Projects/MQTT/main.cpp:242: undefined reference to `MQTTAsync_create'
/home/user/Documents/Projects/MQTT/main.cpp:244: undefined reference to `MQTTAsync_setCallbacks'
/home/user/Documents/Projects/MQTT/main.cpp:251: undefined reference to `MQTTAsync_connect'
/home/user/Documents/Projects/MQTT/main.cpp:271: undefined reference to `MQTTAsync_disconnect'
/home/user/Documents/Projects/MQTT/main.cpp:283: undefined reference to `MQTTAsync_destroy'
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/MQTT.dir/build.make:95: MQTT] Error 1
make[2]: *** [CMakeFiles/Makefile2:68: CMakeFiles/MQTT.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/MQTT.dir/rule] Error 2
make: *** [Makefile:118: MQTT] Error 2
如何正确链接所有这些文件？
也许你应该以这种方式包含你的.h/.hpp 文件：
set (MQTT_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/src/)
target_include_directories (MQTT PUBLIC
${MQTT_INCLUDE_DIR}
)
当然，如果您的 *.h 文件位于另一个目录中，则应更改第一行。
上面的第二行，应该在add_executable之后添加，因为你必须首先创建MQTT目标。
这是一个经典的链接错误，因为您没有指定要链接的库，在您的情况下libpaho-mqtt3a.so.在 CMakeList 中的add_executable行之后添加以下行.txt
target_link_libraries(MQTT paho-mqtt3a)
我知道这是一个老问题，但发布答案，因为它可能对同一问题有用。
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- Link Paho MQTT CMake
