MQTT在C++中接收消息

#include <iostream>
#include <mqtt/async_client.h>

class mqtt_callback : public virtual mqtt::callback
{
    void message_arrived(mqtt::const_message_ptr msg) override
    {
        std::cout << "Received message: " << msg->get_payload_str() << std::endl;
    }
};

int main()
{
    std::string server_address = "tcp://mqtt.example.com:1883";
    std::string client_id = "mqtt_cpp_client";

    mqtt::async_client client(server_address, client_id);
    mqtt_callback callback;
    client.set_callback(callback);

    mqtt::connect_options conn_opts;
    conn_opts.set_keep_alive_interval(20);
    conn_opts.set_clean_session(true);

    try
    {
        client.connect(conn_opts)->wait();
        client.subscribe("#", 1)->wait();

        while (true)
        {
            // 等待和处理接收到的消息
            client.loop();
        }
    }
    catch (const mqtt::exception& exc)
    {
        std::cerr << "Error: " << exc.what() << std::endl;
        return 1;
    }

    return 0;
}