MQTT在Ubuntu下的示例代码

文章目录

• ​​环境安装​​
• ​​CMakeLists.txt​​
• ​​publish​​
• ​​subscribe​​
• ​​代码运行​​

环境安装

sudo apt-get install mosquitto
sudo apt-get install mosquitto-clients
sudo apt-get install mosquitto-dev

CMakeLists.txt

publish

mqtt_pub.cpp

#include <stdio.h>
#include <stdlib.h>
#include <mosquitto.h>
#include <string.h>

#define HOST "localhost"
#define PORT  1883
#define KEEP_ALIVE 60
#define MSG_MAX_SIZE  512

bool session = true;

int main()
{
    char buff[MSG_MAX_SIZE];
    struct mosquitto *mosq = NULL;
    //libmosquitto 库初始化
    mosquitto_lib_init();
    //创建mosquitto客户端
    mosq = mosquitto_new(NULL,session,NULL);
    if(!mosq){
        printf("create client failed..\n");
        mosquitto_lib_cleanup();
        return 1;
    }
    //连接服务器
    if(mosquitto_connect(mosq, HOST, PORT, KEEP_ALIVE)){
        fprintf(stderr, "Unable to connect.\n");
        return 1;
    }
    //开启一个线程，在线程里不停的调用 mosquitto_loop() 来处理网络信息
    int loop = mosquitto_loop_start(mosq);
    if(loop != MOSQ_ERR_SUCCESS)
    {
        printf("mosquitto loop error\n");
        return 1;
    }
    while(fgets(buff, MSG_MAX_SIZE, stdin) != NULL)
    {
                /*发布消息*/
                mosquitto_publish(mosq,NULL,"Gai爷:",strlen(buff)+1,buff,0,0);
                memset(buff,0,sizeof(buff));
    }
    mosquitto_destroy(mosq);
    mosquitto_lib_cleanup();
    return 0;
}

subscribe

mqtt_sub.cpp

#include <stdio.h>
#include <stdlib.h>
#include <mosquitto.h>
#include <string.h>

#define HOST "localhost"
#define PORT  1883
#define KEEP_ALIVE 60

bool session = true;

void my_message_callback(struct mosquitto *mosq, void *userdata, const struct mosquitto_message *message)
{
    if(message->payloadlen){
        printf("%s %s", message->topic, message->payload);
    }else{
        printf("%s (null)\n", message->topic);
    }
    fflush(stdout);
}

void my_connect_callback(struct mosquitto *mosq, void *userdata, int result)
{
    int i;
    if(!result){
        /* Subscribe to broker information topics on successful connect. */
        mosquitto_subscribe(mosq, NULL, "Gai爷:", 2);
    }else{
        fprintf(stderr, "Connect failed\n");
    }
}

void my_subscribe_callback(struct mosquitto *mosq, void *userdata, int mid, int qos_count, const int *granted_qos)
{
    int i;
    printf("Subscribed (mid: %d): %d", mid, granted_qos[0]);
    for(i=1; i<qos_count; i++){
        printf(", %d", granted_qos[i]);
    }
    printf("\n");
}

void my_log_callback(struct mosquitto *mosq, void *userdata, int level, const char *str)
{
    /* Pring all log messages regardless of level. */
    printf("%s\n", str);
}

int main()
{
    struct mosquitto *mosq = NULL;
    //libmosquitto 库初始化
    mosquitto_lib_init();
    //创建mosquitto客户端
    mosq = mosquitto_new(NULL,session,NULL);
    if(!mosq){
        printf("create client failed..\n");
        mosquitto_lib_cleanup();
        return 1;
    }
    //设置回调函数，需要时可使用
    //mosquitto_log_callback_set(mosq, my_log_callback);
    mosquitto_connect_callback_set(mosq, my_connect_callback);
    mosquitto_message_callback_set(mosq, my_message_callback);
    //mosquitto_subscribe_callback_set(mosq, my_subscribe_callback);
    //客户端连接服务器
    if(mosquitto_connect(mosq, HOST, PORT, KEEP_ALIVE)){
        fprintf(stderr, "Unable to connect.\n");
        return 1;
    }
    //循环处理网络消息
    mosquitto_loop_forever(mosq, -1, 1);

    mosquitto_destroy(mosq);
    mosquitto_lib_cleanup();

    return 0;
}

代码运行

首先进行编译

mkdir build && cd build && cmake .. && make

然后运行subscribe和publish

最后进行通讯