我们使用的是paho mqtt软件包，这里介绍一下怎么使用mqtt协议编程。关于鸿蒙系统的mqtt移植好的软件包，相关github链接如下：
https://gitee.com/qidiyun/harmony_mqtt
这里提供一个简单的编程示例：
这里我们使用MQTTClient编程模型，他支持多任务多线程，非常适合用在鸿蒙系统上。
1. 网络初始化
这里定义一个 Network 结构体，然后指定我们的MQTT服务器的IP和端口号。
-
Network
n;
-
//初始化结构体
-
NetworkInit(&n);
-
//连接到指定的MQTT服务器IP、端口号
-
NetworkConnect(&n, “XXX.XXX.XXX.XXX”, XXXX);
2. 设置MQTT缓存和启动MQTT线程
我们这里使用的是MQTT线程功能。
-
MQTTClientInit(
&c,
&n,
1000, buf,
100, readbuf,
100)
;
-
MQTTStartTask(
&c)
;
3. 设置MQTT相关参数
接下来我们设置MQTT的相关参数，包括版本号、客户端ID、账户密码等
-
MQTTPacket_connectData
data = MQTTPacket_connectData_initializer;
-
data.willFlag = 0;
-
//
MQTT版本为 v3
-
data.MQTTVersion = 3;
-
//设置客户端
ID
-
data.clientID.cstring = opts.clientid;
-
//设置客户端账户
-
data.username.cstring = opts.username;
-
//设置客户端密码
-
data.password.cstring = opts.password;
-
data.keepAliveInterval = 10;
-
data.cleansession = 1;
-
-
//连接到
MQTT服务器
-
rc =
MQTTConnect(&c, &
data);
4. 订阅主题和接收消息
订阅主题可以使用如下函数
MQTTSubscribe(&c, topic, opts.qos, messageArrived);它的函数原型如下：
DLLExport int MQTTSubscribe(MQTTClient* client, const char* topicFilter, enum QoS, messageHandler);其中：
MQTTClient* c ：我们前面定义的MQTTClient结构体
const char* topicFilter：订阅的主题
messageHandler messageHandler ：接收到主题信息后的回调处理函数。
例如上面我们的回调函数是 messageArrived ，它的原型如下：
-
void messageArrived(MessageData* md)
-
{
-
MQTTMessage* message = md->message;
-
//打印接收到的消息的长度、和消息内容
-
printf(
"%.*s", (
int)message->payloadlen, (
char*)message->payload);
-
}
5. 发送消息
发送消息也比较简单，我们只需要设置好我们的主题和消息内容即可
-
memset(&pubmsg,
'\0',
sizeof(pubmsg));
-
//消息内容为 hello harmonyOS !
-
pubmsg.payload = (
void*)
"hello harmonyOS !";
-
//消息长度
-
pubmsg.payloadlen =
strlen((
char*)pubmsg.payload);
-
pubmsg.qos = QOS0;
-
pubmsg.retained =
0;
-
pubmsg.dup =
0;
-
-
//推送消息，主题为 pubtest
-
MQTTPublish(&c,
"pubtest", &pubmsg);
完整源码如下：
-
#include <stdio.h>
-
-
#include <unistd.h>
-
-
#include "ohos_init.h"
-
#include "cmsis_os2.h"
-
-
#include <unistd.h>
-
#include "hi_wifi_api.h"
-
//#include "wifi_sta.h"
-
#include "lwip/ip_addr.h"
-
#include "lwip/netifapi.h"
-
-
#include "lwip/sockets.h"
-
-
#include "MQTTClient.h"
-
-
/**
-
* MQTT URI farmat:
-
* domain mode
-
* tcp://iot.eclipse.org:1883
-
*
-
* ipv4 mode
-
* tcp://192.168.10.1:1883
-
* ssl://192.168.10.1:1884
-
*
-
* ipv6 mode
-
* tcp://[fe80::20c:29ff:fe9a:a07e]:1883
-
* ssl://[fe80::20c:29ff:fe9a:a07e]:1884
-
*/
-
#define MQTT_URI "tcp://106.13.62.194:1883"
-
-
struct opts_struct
-
{
-
char* clientid;
-
int nodelimiter;
-
char* delimiter;
-
enum QoS qos;
-
char* username;
-
char* password;
-
char* host;
-
int port;
-
int showtopics;
-
} opts =
-
{
-
(
char*)
"stdout-subscriber",
0, (
char*)
"\n", QOS2,
NULL,
NULL, (
char*)
"106.13.62.194",
1883,
1
-
};
-
-
-
void messageArrived(MessageData* md)
-
{
-
MQTTMessage* message = md->message;
-
-
if (opts.showtopics)
-
printf(
"%.*s\t", md->topicName->lenstring.len, md->topicName->lenstring.data);
-
if (opts.nodelimiter)
-
printf(
"%.*s", (
int)message->payloadlen, (
char*)message->payload);
-
else
-
printf(
"%.*s%s", (
int)message->payloadlen, (
char*)message->payload, opts.delimiter);
-
//fflush(stdout);
-
}
-
-
-
unsigned
char buf[
100];
-
unsigned
char readbuf[
100];
-
-
int mqtt_test(void)
-
{
-
int rc =
0;
-
-
MQTTMessage pubmsg;
-
-
-
char* topic =
"test";
-
-
if (
strchr(topic,
'#') ||
strchr(topic,
'+'))
-
opts.showtopics =
1;
-
if (opts.showtopics)
-
printf(
"topic is %s\n", topic);
-
-
Network n;
-
MQTTClient c;
-
-
NetworkInit(&n);
-
NetworkConnect(&n, opts.host, opts.port);
-
-
MQTTClientInit(&c, &n,
1000, buf,
100, readbuf,
100);
-
MQTTStartTask(&c);
-
-
MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
-
data.willFlag =
0;
-
data.MQTTVersion =
3;
-
data.clientID.cstring = opts.clientid;
-
data.username.cstring = opts.username;
-
data.password.cstring = opts.password;
-
-
data.keepAliveInterval =
10;
-
data.cleansession =
1;
-
printf(
"Connecting to %s %d\n", opts.host, opts.port);
-
-
rc = MQTTConnect(&c, &data);
-
printf(
"Connected %d\n", rc);
-
-
-
-
printf(
"Subscribing to %s\n", topic);
-
rc = MQTTSubscribe(&c, topic, opts.qos, messageArrived);
-
printf(
"Subscribed %d\n", rc);
-
-
memset(&pubmsg,
'\0',
sizeof(pubmsg));
-
pubmsg.payload = (
void*)
"hello harmonyOS !";
-
pubmsg.payloadlen =
strlen((
char*)pubmsg.payload);
-
pubmsg.qos = QOS0;
-
pubmsg.retained =
0;
-
pubmsg.dup =
0;
-
-
-
-
while (
1)
-
{
-
MQTTPublish(&c,
"pubtest", &pubmsg);
-
sleep(
1);
-
}
-
-
printf(
"Stopping\n");
-
-
MQTTDisconnect(&c);
-
NetworkDisconnect(&n);
-
-
return
0;
-
}
转载：https://blog.csdn.net/aa120515692/article/details/110087293
查看评论