3、mqtt客户端演示（MQTT通信协议(mosquitto)发布订阅 C语言实现）

可订阅可发布模式

具体代码

客户端1代码：pub.c

#include 
#include 
#include 
#include 
 
#define HOST "localhost"
#define PORT  1883
#define KEEP_ALIVE 60
#define MSG_MAX_SIZE  512
 
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, (char *)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, "topic2 ", 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

客户端2代码：sub.c 

#include 
#include 
#include 
#include 
 
#define HOST "localhost"
#define PORT  1883
#define KEEP_ALIVE 60
#define MSG_MAX_SIZE  512
#define TOPIC_NUM 3
 
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, (char *)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, "topic1 ", 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

makefile文件：

all:
    @echo ""
    @echo "Start compiling......"
    @echo ""
    gcc -o sub sub.c -lmosquitto
    gcc -o pub pub.c -lmosquitto
    @echo "end"
sub:
    gcc -o sub sub.c -lmosquitto 

pub:
    gcc -o pub pub.c -lmosquitto 

clean:
    -rm sub pub

运行结果

1、先执行make
2、启动mosquitto服务器
3、运行pub和sub
4、测试发布订阅信息,每个客户端都可以发布和订阅，双向收发。