Python 如何使用MQTT和Flask在web上做出响应？

我对MQTT lib（）有问题

我希望为多个请求提供异步和同步任务，但似乎我无法回避一个问题，即在收到实际订阅的消息时，在web上对请求的url/mqtt做出响应，因为on_消息是一个回调函数

@app.route('/mqtt', methods=['POST', 'GET'])
def main():
            client = mqtt.Client()
            client.on_connect = on_connect
            client.on_message = on_message
            test = on_message
            client.username_pw_set('x', 'x')
            client.connect("x", 1883, 60)
            client.subscribe("/message/1")

            client.loop_forever()

            # how do I get the message from callback function on_message and then stop loop_forever?
#I thought about: return msg but it doesn't work.


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

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    #how to pass this msg to the main function?


    print(msg.topic + " " + str(msg.payload))

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要在收到消息时永远停止循环，您可以使用

客户端。断开连接

示例代码：

def on_message(client, userdata, msg):
    print(msg.topic + " " + str(msg.payload))
    client.disconnect() # disconnect when get message

要将消息传递给main函数，只需使用全局变量。但我的建议是为mqtt客户机启动另一个进程，通过共享内存传递变量。每次获得GET或POST时，连接到mqtt代理都会产生大量开销