怎样进行鸿蒙编程,在鸿蒙系统上使用mqtt编程[通俗易懂] -金沙1005

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

#include

#include “ohos_init.h”

#include “cmsis_os2.h”

#include

#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;

}