使用 Paho Python 连接到部署

本文主要介绍如何在 Python 项目中使用 paho-mqtt 客户端库，实现客户端与 MQTT 服务器的连接、订阅、取消订阅、收发消息等功能。

paho-mqtt 是目前 Python 中使用较多的 MQTT 客户端库，它在 Python 2.7.9+ 或 3.6+ 上为客户端类提供了对 MQTT v5.0，v3.1 和 v3.1.1 的支持。它还提供了一些帮助程序功能，使将消息发布到 MQTT 服务器变得非常简单。

前置准备

获得 MQTT 服务器

使用 EMQX 提供的免费公共 MQTT 服务器（仅支持单向认证），该服务基于 EMQX 的全托管的 MQTT 消息云服务创建。服务器连接信息如下：
- 连接地址: broker.emqx.io
- TCP Port: 1883
- SSL/TLS Port: 8883
- WebSocket 端口: 8083
- WebSocket TLS/SSL 端口: 8084
您也可以自己创建部署，在部署概览下可以查看到连接相关的信息，请确保部署状态为运行中。使用 TCP 端口或 SSL/TLS 端口测试连接到 MQTT 服务器。如果您是自己创建部署，请设置认证鉴权，在部署控制台认证鉴权 > 认证 中设置用户名和密码，用于连接验证。

检查 Python 版本

本项目使用 Python 3.8 进行开发测试，可用如下命令确认 Python 的版本。

➜  ~ python3 --version             
Python 3.8.6

➜  ~ python3 --version             
Python 3.8.6

安装 MQTT 客户端

Pip 是 Python 包管理工具，该工具提供了对 Python 包的查找、下载、安装、卸载的功能，使用以下命令安装 paho-mqtt。

bash

pip install paho-mqtt

pip install paho-mqtt

导入 Paho MQTT 客户端

python

from paho.mqtt import client as mqtt_client

from paho.mqtt import client as mqtt_client

通过 TCP 端口连接

请在控制台的部署概览找到相关的地址以及端口信息，需要注意如果是基础版，端口不是 1883 端口，请确认好端口

设置 MQTT Broker 连接地址，端口以及 topic，同时我们调用 Python random.randint 函数随机生成 MQTT 客户端 id。

python

broker = 'broker.emqx.io'
port = 1883
topic = 'python/mqtt'
client_id = f'python-mqtt-{random.randint(0, 1000)}'
# 如果 broker 需要鉴权，设置用户名密码
username = 'emqx'
password = '**********'

broker = 'broker.emqx.io'
port = 1883
topic = 'python/mqtt'
client_id = f'python-mqtt-{random.randint(0, 1000)}'
# 如果 broker 需要鉴权，设置用户名密码
username = 'emqx'
password = '**********'

编写连接回调函数 on_connect，该函数将在客户端连接后被调用，在该函数中可以依据 rc 来判断客户端是否连接成功。

python

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)

    # Set Connecting Client ID
    client = mqtt_client.Client(client_id)
    client.username_pw_set(username, password)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client

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)

    # Set Connecting Client ID
    client = mqtt_client.Client(client_id)
    client.username_pw_set(username, password)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client

通过 SSL/TLS 端口连接

请在控制台的部署概览找到相关的地址以及端口信息，需要注意如果是基础版，端口不是 8883 端口，请确认好端口

本节介绍了如何通过 SSL/TLS 单向认证方式连接到部署。若您需使用双向认证方式，可以参考这里。

设置 MQTT Broker 连接地址，端口以及 topic，同时我们调用 Python random.randint 函数随机生成 MQTT 客户端 id。

python

broker = 'broker.emqx.io'
port = 8883
topic = 'python/mqtt'
client_id = f'python-mqtt-{random.randint(0, 1000)}'
# 如果 broker 需要鉴权，设置用户名密码
username = 'emqx'
password = '**********'

broker = 'broker.emqx.io'
port = 8883
topic = 'python/mqtt'
client_id = f'python-mqtt-{random.randint(0, 1000)}'
# 如果 broker 需要鉴权，设置用户名密码
username = 'emqx'
password = '**********'

设置 CA 证书，如果您使用 Serverless 或者基础版部署，您可以在部署概览中下载 CA 证书文件。如果您使用专业版部署，请参考专业版 TLS/SSL 配置进行证书配置。
编写连接回调函数 on_connect，该函数将在客户端连接后被调用，在该函数中可以依据 rc 来判断客户端是否连接成功。

python

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)
    # Set Connecting Client ID
    client = mqtt_client.Client(client_id)
    # Set CA certificate
    client.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client

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)
    # Set Connecting Client ID
    client = mqtt_client.Client(client_id)
    # Set CA certificate
    client.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client

订阅和发布

本节主要介绍了如何在已连接到部署的情况下订阅主题并发布消息。

订阅主题

设置将要订阅的主题及对应 QoS 等级。
编写消息回调函数 on_message，该函数将在客户端从 MQTT Broker 收到消息后被调用，在该函数中我们将打印出订阅的 topic 名称以及接收到的消息内容。

python

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

    client.subscribe(topic=topic, qos=0)
    client.on_message = on_message

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

    client.subscribe(topic=topic, qos=0)
    client.on_message = on_message

取消订阅

通过以下代码取消订阅，此时应指定取消订阅的主题。

python

def unsubscribe(client: mqtt_client):
    client.on_message = None
    client.unsubscribe(topic)

def unsubscribe(client: mqtt_client):
    client.on_message = None
    client.unsubscribe(topic)

发布消息

发布消息时需要告知 MQTT Broker 目标主题及消息内容。
首先定义一个 while 循环语句，在循环中我们将设置每秒调用 MQTT 客户端 publish 函数向 python/mqtt 主题发送消息。

python

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 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

接收消息

通过以下代码指定客户端对消息事件进行监听，并在收到消息后执行回调函数，将接收到的消息及其主题打印到控制台。

python

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

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

断开连接

如客户端希望主动断开连接，可以通过如下代码实现：

python

def disconnect(client: mqtt_client):
    client.loop_stop()
    client.disconnect()

def disconnect(client: mqtt_client):
    client.loop_stop()
    client.disconnect()

以上部分仅列出了一些关键代码，项目完整代码请见这里，您可以进行下载并体验。

完整代码

消息发布代码

python

# python 3.8

import random
import time

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
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):
        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.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    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()

# python 3.8

import random
import time

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
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):
        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.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    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()

消息订阅代码

python

# python3.8

import random

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
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):
        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.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    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()

# python3.8

import random

from paho.mqtt import client as mqtt_client


broker = 'broker.emqx.io'
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):
        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.tls_set(ca_certs='./server-ca.crt')
    client.username_pw_set(username, password)
    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()

测试验证

运行代码，控制台输出如下

消息发布

python_pub

消息订阅

python_sub

创建专有版部署

单点登录 (SSO)

Serverless API

专有版 / BYOC API

使用 Paho Python 连接到部署

前置准备

获得 MQTT 服务器

检查 Python 版本

安装 MQTT 客户端

通过 TCP 端口连接

通过 SSL/TLS 端口连接

订阅和发布

订阅主题

取消订阅

发布消息

接收消息

断开连接

完整代码

测试验证

消息发布

消息订阅

更多内容

使用 Paho Python 连接到部署 ​

前置准备 ​

获得 MQTT 服务器 ​

检查 Python 版本 ​

安装 MQTT 客户端 ​

通过 TCP 端口连接 ​

通过 SSL/TLS 端口连接 ​

订阅和发布 ​

订阅主题 ​

取消订阅 ​

发布消息 ​

接收消息 ​

断开连接 ​

完整代码 ​

测试验证 ​

消息发布 ​

消息订阅 ​

更多内容 ​

使用 Paho Python 连接到部署

前置准备

获得 MQTT 服务器

检查 Python 版本

安装 MQTT 客户端

通过 TCP 端口连接

通过 SSL/TLS 端口连接

订阅和发布

订阅主题

取消订阅

发布消息

接收消息

断开连接

完整代码

测试验证

消息发布

消息订阅

更多内容