linux下MQTT服务器(EMQX)搭建及paho.mqtt.c客户端开发_linux emqx

前言：

一.linux下EMQX服务器搭建

1.下载deb包

2.安装

3.运行

即可验证自己服务器安装的是否成功，用户名是 admin,初始密码 public

二.客户端工具MQTTX的安装

 我用的是windows下的，接着安装运行直接下一步走下去就行了。

三.linux下paho.mqtt.c的开发

1. paho.mqtt.c下载

git clone https://github.com/eclipse/paho.mqtt.c.git
cd paho.mqtt.c
mkdir build
cd build
cmake ..
make 
make install

安装完成会在/usr/local/include和/usr/local/lib下看见mqtt的头文件和动态库。

 2.mqtt代码开发

#include <MQTTAsync.h>  //换成你自己的安装路径，不然回报错
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#define  SERVERIP "xxx"  //换成你自己的服务器
#define Clientid "sza123"    //这个随便写
int isConnected=0;
//消息回调函数
int onMessrecv(void* context,char*topicName,int topicLen,MQTTAsync_message*message){
            printf("recv name:\ntopic:%s,payload:%s\n",topicName,(char*)message->payload);
            MQTTAsync_free(topicName);
            MQTTAsync_free(message);
            return 1;         
}
void onSubscribe(void* context,MQTTAsync_successData* response){
    printf("sub success!");
}
//连接mqtt服务器
void onConnect(void *context,MQTTAsync_successData* response)
{
    MQTTAsync client =(MQTTAsync)context;
    int ret;
    MQTTAsync_responseOptions response_opt=MQTTAsync_responseOptions_initializer;
    printf("Succeed in connecting to mqtt-server!\n");
    response_opt.onSuccess=onSubscribe;
    ret=MQTTAsync_subscribe(client,"/pub",1,&response_opt);//订阅/pub主题消息
    if(ret!=MQTTASYNC_SUCCESS){
        printf("fail to sub!\n");
    }
    isConnected=1;
}
void disConnect(void *context,MQTTAsync_failureData* response)
{
    printf("Failed to connect  mqtt-server!\n");
}
void onSend(void* context,MQTTAsync_successData* response){
    printf("send message to mqtt server success!\n");
}
int main()
{
    MQTTAsync client;
    int ret;
    MQTTAsync_connectOptions conn_opt = MQTTAsync_connectOptions_initializer;//初始化连接选项
    ret=MQTTAsync_create(&client,SERVERIP,Clientid,MQTTCLIENT_PERSISTENCE_NONE,NULL);
    if(ret!=MQTTASYNC_SUCCESS)
    {
        printf("Cannot create mqtt client!\n");
        return -1;
    }
    //初始化接收消息回调
    ret=MQTTAsync_setCallbacks(client,NULL,NULL,onMessrecv,NULL);
    if(ret!=MQTTASYNC_SUCCESS){
        printf("cannnot set call back function!\n");
        return  -1;
    }
    conn_opt.onSuccess=onConnect;
    conn_opt.onFailure=disConnect;
    conn_opt.automaticReconnect=1;
    conn_opt.context=client;
    conn_opt.cleansession=0;
    //conn_opt.username="xxx";//设置用户名密码换成自己的
    //conn_opt.password="xxx";
    ret=MQTTAsync_connect(client,&conn_opt);
    //因为是异步的，当MQTTAsync_connect返回的时候只是代表底层代码对参数进行了检查
    //当正确返回时，表示底层代码接收了该connect连接命令
    if(ret!=MQTTASYNC_SUCCESS)
    {
        printf("Cannot start a mqttt server connect!\n");
        return -1;
    }
    while (1){
        //1表示成功连接到我们的服务器
        if(isConnected==1){
            MQTTAsync_message message=MQTTAsync_message_initializer;
            MQTTAsync_responseOptions res_option=MQTTAsync_responseOptions_initializer;
            char buffer[200];
            static int temp=16;
            static int humid=58;
            sprintf(buffer," temp:%d,humid：%d ",temp++,humid++);
            message.payload=buffer;
            message.payloadlen=strlen(buffer);
            message.qos=1;
            res_option.onSuccess=onSend;
            printf("read the message is :");
            //发布消息
            ret=MQTTAsync_sendMessage(client,"/sensor/dht11/0",&message,&res_option);//发送消息
            if(ret!=MQTTASYNC_SUCCESS){
                printf("参数错误！");
            }
                   sleep(10);  
                   if(temp>30|humid>90){
                       temp=16;
                       humid=58;
                   }
        }
    }
    return 0;
}
 
 

 然后编译

gcc mqtt.c -o mqtt -I /usr/local/include/ -lpaho-mqtt3a

运行mqtt

 

 此时windows上的客户端工具就会接收相应的内容，也可以向linux客户端发送消息。