c 建立mqtt连接
时间: 2023-08-22 15:11:45 浏览: 109
您好!要在 C 中建立 MQTT 连接,您可以使用开源的 MQTT 客户端库,例如 Paho MQTT C。以下是一个简单的示例代码,演示如何建立 MQTT 连接并发布消息:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <MQTTClient.h>
#define ADDRESS "tcp://mqtt.example.com:1883"
#define CLIENTID "ExampleClient"
#define TOPIC "test/topic"
#define QOS 1
#define TIMEOUT 10000L
int main()
{
MQTTClient client;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
int rc;
MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to connect to MQTT broker, return code %d\n", rc);
exit(EXIT_FAILURE);
}
char payload[100];
sprintf(payload, "Hello from MQTT client");
MQTTClient_message pubmsg = MQTTClient_message_initializer;
pubmsg.payload = payload;
pubmsg.payloadlen = strlen(payload);
pubmsg.qos = QOS;
pubmsg.retained = 0;
MQTTClient_deliveryToken token;
if ((rc = MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to publish message, return code %d\n", rc);
exit(EXIT_FAILURE);
}
printf("Message published: %s\n", payload);
printf("Waiting for publication acknowledgment...\n");
rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
printf("Message acknowledged\n");
MQTTClient_disconnect(client, TIMEOUT);
MQTTClient_destroy(&client);
return rc;
}
```
请将 `ADDRESS` 修改为您的 MQTT 代理服务器地址,`CLIENTID` 修改为您指定的客户端 ID,`TOPIC` 修改为您要发布消息的主题。您还可以根据需要调整其他连接选项。
这只是一个简单的示例,您可以根据自己的需求进行扩展和修改。希望对您有所帮助!如有其他问题,请随时提问。