python mqtt简单使用。

1、安装mqtt服务器。

1、 脚本安装
curl https://repos.emqx.io/install_emqx.sh | bash

2、 docker安装
（1）先把emqx 里面得配置文件复制出来
docker cp emqx:/opt/emqx $PWD/emqx

docker run -d --name emqx -p 1883:1883 -p 8083:8083 -p 8883:8883 -p 8084:8084 -p 18083:18083 -v $PWD/emqx:/opt/emqx emqx/emqx:v4.0.0

2、 使用python使用mqtt 。 发布者、订阅者都是属于客户端。

import paho.mqtt.client as mqtt
import time

a = 0

def on_connect(client, userdata, flags, rc):
    print("Connected with result code: " + str(rc))


def on_demo1_msg(client, userdata, msg):
    print(msg.topic + " " + str(msg.payload))
    # 发送给demo2
    time.sleep(1)
    client.publish("demo2", payload="hello, i am demo1")


def on_demo2_msg(client, userdata, msg):
    print(msg.topic + " " + str(msg.payload))
    # 发送给demo2
    time.sleep(1)
    client.publish("demo1", payload="hello, i am demo2")
    global a
    a += 1
    if a==10:
        client.disconnect()


def on_disconnect(client, userdata, rc):
    print("disconnect, ", str(rc))



client = mqtt.Client()  # 实例化客户端
client.on_connect = on_connect  客户端连接回调函数（触发）

# client.on_message这个的升级版？ 可以触发多个接受函数。
client.message_callback_add("demo1", on_demo1_msg) 接受主题的触发函数
client.message_callback_add("demo2", on_demo2_msg)


client.on_disconnect = on_disconnect  # 关闭客户端的回调汉书

client.connect('127.0.0.1', 1883, 600) # 600为keepalive的时间间隔
client.subscribe('demo1', qos=0)  # 订阅主题
client.subscribe('demo2', qos=0)  # 订阅主题

client.publish("demo1", payload="hello, begin the loop") # 发布消息
client.loop_forever() # 保持连接