Question

我有一个示例代码，用于从 Mqtt经纪人

获取消息

import paho.mqtt.client as mqtt

def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))
    client.subscribe("123")
def on_message(client, userdata, msg):
    x = int(msg.payload)*10
    print(msg.topic+" "+str(msg.payload))

client = mqtt.Client()
client.connect("broker.hivemq.com", 1883)
client.on_connect = on_connect
client.on_message = on_message
client.loop_forever()

如何在msg.payload中获取on_message的变量？

我在x的函数中添加on_connect变量：

def on_message(client, userdata, msg):
    x = int(msg.payload)*10
    print(msg.topic+" "+str(msg.payload))
    return x

问题：如何获取变量x？

Answer 1

我解决这个问题的方法如下：

import paho.mqtt.client as mqtt
msg_arrived_flag = False
global_X = 0


def on_connect(client, userdata, flags, rc):
  print("Connected with result code "+str(rc))
  client.subscribe("123")
def on_message(client, userdata, msg):
  global_X = int(msg.payload)*10
  print(msg.topic+" "+str(msg.payload))
  msg_arrived_flag = True

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect("broker.hivemq.com", 1883)

while True:
  client.loop_start()
  time.sleep(5)
  client.loop_stop()
  if msg_arrived_flag:
    msg_arrived_flag = False
    #Use global_X here

可以将开始和停止之间的睡眠时间设置为方便。另外我建议在连接之前设置回调。希望这有帮助！

如何获得关于Python paho Mqtt

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