MQTT接口的使用

      

　  MQTT 是一種基於發布/訂閱模式的 輕量級物聯網消息傳輸協議 ，可以用極少的代碼和帶寬為聯網設備提供實時可靠的消息服務，它廣泛應用於物聯網、移動互聯網、智能硬件、車聯網、電力能源等行業。

 

      因為公司下一個項目會使用MQTT接口，所以需要提前熟悉一下。

     下面主要了解如何在 Python 項目中使用 paho-mqtt 客戶端庫 ，實現客戶端與 MQTT 服務器的連接、訂閱、取消訂閱、收發消息等功能。

　　

Python MQTT 使用

    連接 MQTT 服務器

    本次將使用 EMQ X 提供的 免費公共 MQTT 服務器，該服務基於 EMQ X 的 MQTT 物聯網雲平台 創建。服務器接入信息如下：

• Broker:192.168.1.51
• TCP Port: 1883
• Websocket Port: 8083

導入 Paho MQTT客戶端

from paho.mqtt import client as mqtt_client

 

消息發布代碼

# python 3.6

import random
import time

from paho.mqtt import client as mqtt_client


broker = '192.168.1.51'
port = 1883
topic = "zhoufu nb"
# generate client ID with pub prefix randomly
client_id = f'python-mqtt-{random.randint(0, 1000)}'


def connect_mqtt():
    def on_connect(client, userdata, flags, rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %d\n", rc)

    client = mqtt_client.Client(client_id)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client


def publish(client):
    msg_count = 0
    while True:
        time.sleep(1)
        msg = f"messages: {msg_count}"
        result = client.publish(topic, msg)
        # result: [0, 1]
        status = result[0]
        if status == 0:
            print(f"Send `{msg}` to topic `{topic}`")
        else:
            print(f"Failed to send message to topic {topic}")
        msg_count += 1


def run():
    client = connect_mqtt()
    client.loop_start()
    publish(client)


if __name__ == '__main__':
    run()

 

消息訂閱代碼

# python3.6

import random

from paho.mqtt import client as mqtt_client


broker = '192.168.1.51'
port = 1883
topic = "zhoufu nb"


client_id = f'python-mqtt-{random.randint(0, 100)}'


def connect_mqtt() -> mqtt_client:
    def on_connect(client, userdata, flags, rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %d\n", rc)

    client = mqtt_client.Client(client_id)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client


def subscribe(client: mqtt_client):
    def on_message(client, userdata, msg):
        print(f"Received `{msg.payload.decode()}` from `{msg.topic}` topic")

    client.subscribe(topic)
    client.on_message = on_message


def run():
    client = connect_mqtt()
    subscribe(client)
    client.loop_forever()


if __name__ == '__main__':
    run()