Python实现MQTT通信的示例代码

目录

• 1. 安装paho-mqtt库‌
• 2. 搭建MQTT代理服务器（Broker）‌
• ‌3. Python实现基础通信功能‌
• 关键配置说明
• 4. 关键功能扩展
• 5. 注意事项‌
• ‌完整示例流程‌

 适用于物联网设备、传感器数据采集等场景

安装Python的MQTT客户端库 paho-mqtt，支持MQTT v3.1/v3.1.1协议，兼容性强

pip install paho-mqtt==1.6.1  # 推荐使用1.6.1版本避免兼容性问题

选择本地搭建或使用公共Broker：

‌本地搭建（以EMQX为例）‌

下载并解压EMQX开源版。Directory listing for EMQX: /v5.3.2/ | EMQ

配置EMQX，EMQX的配置文件位于etcemqx.conf，可以根据需要修改配置文件，例如更改端口号、添加插件等：18083 EMQX Dashboard 管理控制台端口

在命令行中进入安装目录的 bin 文件夹，执行以下命令启动服务

检查启动状态emqx_ctl status

访问 http://localhost:18083 进入管理界面（默认账号：admin/public）

公共Broker（如HiveMQ）‌

使用免费公共服务器： 

broker_address = "broker.hivemq.com"  
broker_port = 1883  

分为 ‌发布者（Publisher）‌ 和 ‌订阅者（Subscriber）‌ 两类客户端：

‌3.1 发布者代码示例publisher.py

# python 3.8

import random
import time

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
port = 1883
broker = '127.0.0.1'
port = 1883
topic = "python/mqtt"
# generate client ID with pub prefix randomly
client_id = f'python-mqtt-{random.randint(0, 1000)}'
username = 'emqx'
password = '**********'


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

    # client = mqtt_client.Client(client_id)
    client = mqtt_client.Client(client_id=client_id, callback_api_version=mqtt_client.CallbackAPIVersion.VERSION2)
    # client.tls_set(ca_certs='./server-ca.crt')
    # client.username_pw_set(username, password)
    client.username_pw_set('admin', 'public')
    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()

3.2 订阅者代码示例subscriber.py

# python3.8

import random

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
port = 1883
broker = '127.0.0.1'
port = 1883
topic = "python/mqtt"
# generate client ID with pub prefix randomly
client_id = f'python-mqtt-{random.randint(0, 100)}'
username = 'emqx'
password = '**********'


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

    # client = mqtt_client.Client(client_id)
    client = mqtt_client.Client(client_id=client_id, callback_api_version=mqtt_client.CallbackAPIVersion.VERSION2)
    # client.tls_set(ca_certs='./server-ca.crt')
    # client.username_pw_set(username, password)
    client.username_pw_set('admin', 'public')
    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()

3.3或者放同一个文件：

from paho.mqtt import client as mqtt_client
from threading import Thread
import time

broker = '127.0.0.1'
port = 1883
# broker = 'broker.emqx.io'
# port = 1883
su_topic = [("python_mqtt_server", 2), ("python_mqtt_command", 2)]  # 订阅频道,数组格式为(topic，qos)
pu_topic = ["python_mqtt_server"]  # 发布频道
client_id = 'websocket_publisher_001'


# 将连接与订阅绑在一起，防止复用client导致连接冲突
def connect_mqtt():
    # For paho-mqtt 2.0.0, you need to add the properties parameter.
    def on_connect(client, userdata, flags, rc, properties):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %dn", rc)

    # For paho-mqtt 2.0.0, you need to set callback_api_version.
    client = mqtt_client.Client(client_id=client_id, callback_api_version=mqtt_client.CallbackAPIVersion.VERSION2)

    client.username_pw_set('admin', 'public')
    client.on_connect = on_connect
    client.connect(broker, port)
    subscribe_many(client)
    print("订阅完成")
    return client


# 订阅多个频道
def subscribe_many(client):
    # 根据client源码可知，订阅支持的数组格式是(topic,qos)
    client.subscribe(su_topic)


# 收到信息的回调函数
def on_message(client, userdata, msg):
    print(f"Received `{msg.payload.decode()}` from `{msg.topic}` topic")
    # 这里可以编写一些收到信息后的处理,比如收到什么信息开启什么任务，任务完成后再调publish发布信息给终端等等........
    # ----------处理例子------------------
    r_msg = msg.payload.decode()
    if int(r_msg) % 2 == 0:
        print("收到偶数")
    # -----------------------------------


# 发布信息函数
def publish(client):
    for i in range(1, 11):
        time.sleep(1)
        msg = f"{i}"
        result = client.publish(pu_topic[0], msg)
        # result: [0, 1]
        status = result[0]
        if status == 0:
            print(f"Send `{msg}` to topic `{pu_topic[0]}`")
        else:
            print(f"Failed to send message to topic {pu_topic[0]}")


if __name__ == '__main__':
    client = connect_mqtt()
    client.username_pw_set('admin','public')
    client.on_message = on_message  # 重写回调函数,可以在方法体里，根据需求改收到信息后干什么
    # 多线程，这里启动一个发布任务的线程，模拟有一个发布消息的客户端
    thread1 = Thread(target=publish, args=(client,))
    # --*如要要实现流水线式的收发，则可以将线程内方法改为任务队列处理，用一个全局变量管理任务执行，执行后再publish
    thread1.start()

    client.loop_forever()  # 这个要加,监听(on_message)与loop_forever配套

订阅所有传感器子主题

client.subscribe("sensors/#", qos=1) ‌

‌WebSocket协议支持‌

• 必须设置 transport="websockets"，否则默认使用TCP连接。
• 端口需与Broker配置匹配（例如EMQX默认WebSocket端口为8083）。

‌QoS与消息保留‌

• qos=1：确保消息至少送达一次。
• retain=True：Broker保留最后一条消息，新订阅者立即收到。

‌异常处理‌

• 使用 try-except 捕获网络中断或Broker不可用问题。
• loop_start() 适用于需要异步处理的场景（如GUI应用）。

异步通信，使用多线程实现非阻塞操作：

from threading import Thread  

  def start_async(client):  
      Thread(target=client.loop_start).start()  

服务质量（QoS）设置 支持至多一次（0）、至少一次（1）、恰好一次（2）三种级别：

client.publish(topic, payload, qos=1)  # 设置QoS为1

1. ‌连接安全性‌：若需SSL加密，可使用 client.tls_set() 方法。
2. ‌主题设计‌：遵循分层结构（如 sensor/room1/temp），支持通配符 +（单层）和 #（多层）。
3. ‌异常处理‌：添加 on_disconnect 回调函数实现断线重连逻辑。

1. 启动EMQX Broker服务。
2. 运行订阅者代码监听主题 home/sensor/temp。
3. 运行发布者代码发送温度数据。
4. 在EMQX管理界面验证消息收发状态

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