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基于C++在windows下使用mosquitto实现MQTT订阅客户端

news 2026/3/26 21:53:10

1、MOSQUITTO订阅客户端搭建

  1 #include <iostream>
  2 #include <iostream>
  3 #include <thread>
  4 #include <mosquitto.h>
  5 
  6 //mqtt
  7 #define MQTT_USER_NAME "admin"
  8 #define MQTT_PASS_WORD "123456"
  9 #define MQTT_SERVER_IP_ADDRESS "10.57.6.250"
 10 #define MQTT_SERVER_PORT 1883
 11 #define PUBLISH_JSON_DATA_ORG "4321"
 12 static struct mosquitto* mosq;
 13 static bool mqtt_init_sign;
 14 //mqtt
 15 
 16 void on_message(struct mosquitto* mosq, void* userdata, const struct mosquitto_message* msg) {
 17     std::cout << "\nrev msg:" << std::endl;
 18     std::cout << "the topic of the msg is: " << msg->topic << std::endl;
 19 
 20     if (msg->payloadlen > 0) {
 21         std::string message(static_cast<char*>(msg->payload), msg->payloadlen);
 22         std::cout << "the msg content is: " << message.c_str() << std::endl;
 23     }
 24     else {
 25         std::cout << "the msg content is:null" << std::endl;
 26     }
 27 
 28     std::cout << "QoS: " << msg->qos << std::endl;
 29     std::cout << "the ID of the msg is: " << msg->mid << std::endl;
 30     std::cout << "---------------------" << std::endl;
 31 }
 32 
 33 void on_connect(struct mosquitto *mosq, void *obj, int rc) {
 34     if (rc == 0) {
 35         printf("authentication success\n");
 36     }
 37     else {
 38         printf("connect failed: %s\n", mosquitto_strerror(rc));
 39     }
 40 }
 41 
 42 void on_disconnect(struct mosquitto *mosq, void *obj, int rc) {
 43     printf("disconnect: %s\n", mosquitto_strerror(rc));
 44 
 45     if (rc == MOSQ_ERR_AUTH) {
 46         printf("error：authentication failure(username/password is wrong)\n");
 47     }
 48     else if (rc == MOSQ_ERR_CONN_REFUSED) {
 49         printf("error：access refused\n");
 50     }
 51 }
 52 
 53 int init_mqtt(const std::string username, const std::string passwd, const std::string hostname, const int port)
 54 {
 55     mosquitto_lib_init();
 56 
 57     mosq = mosquitto_new(nullptr, true, nullptr);//第一个形参制定为一个值后，派生类会出现发布数据失败的情况，因为不同的派生类共用一个client_id
 58     if (!mosq) {
 59         std::cerr << "Failed to create mosquitto instance!" << std::endl;
 60         return 0;
 61     }
 62 
 63     mosquitto_connect_callback_set(mosq, on_connect);
 64     mosquitto_disconnect_callback_set(mosq, on_disconnect);
 65     mosquitto_message_callback_set(mosq, on_message);
 66 
 67     const char* usrname = username.c_str();
 68     const char* password = passwd.c_str();
 69 
 70     int rc = mosquitto_username_pw_set(mosq, usrname, password);
 71     if (rc != MOSQ_ERR_SUCCESS) {
 72         std::cerr << "Failed to set username/password: " << mosquitto_strerror(rc) << std::endl;
 73         mosquitto_destroy(mosq);
 74         mosquitto_lib_cleanup();
 75         return 0;
 76     }
 77 
 78     rc = mosquitto_connect(mosq, hostname.c_str(), port, 60);
 79     if (rc != MOSQ_ERR_SUCCESS) {
 80         std::cerr << "Connection failed: " << mosquitto_strerror(rc) << std::endl;
 81 
 82         std::cout << "Trying without authentication..." << std::endl;
 83         mosquitto_username_pw_set(mosq, nullptr, nullptr);
 84 
 85         rc = mosquitto_connect(mosq, hostname.c_str(), port, 60);
 86         if (rc != MOSQ_ERR_SUCCESS) {
 87             std::cerr << "Still failed: " << mosquitto_strerror(rc) << std::endl;
 88             mosquitto_destroy(mosq);
 89             mosquitto_lib_cleanup();
 90             return 0;
 91         }
 92     }
 93 
 94     mosquitto_loop_start(mosq);
 95     mqtt_init_sign = true;
 96     return 1;
 97 }
 98 
 99 void subscribe_msg_from_server()
100 {
101     const char* topic = "TestMqttTopic";
102     int qos = 1;  // 服务质量等级 0,1,2
103 
104     int result = mosquitto_subscribe(mosq, NULL, topic, qos);
105     if (result != MOSQ_ERR_SUCCESS) {
106         std::cerr << "订阅失败: " << mosquitto_strerror(result) << std::endl;
107     }
108     else {
109         std::cout << "已订阅主题: " << topic << std::endl;
110     }
111 }
112 
113 int main()
114 {
115     init_mqtt(MQTT_USER_NAME, MQTT_PASS_WORD, MQTT_SERVER_IP_ADDRESS, MQTT_SERVER_PORT);
116 
117     while (1)
118     {
119         std::this_thread::sleep_for(std::chrono::milliseconds(5000));
120         std::cout << "start subscribe!" << std::endl;
121         subscribe_msg_from_server();
122     }
123 }