您可以在on_connect中激活一个标志，而在on_disconnect中禁用它。这样，您可以知道客户端是否已连接。
import paho.mqtt.client as mqttflag_connected = 0def on_connect(client, userdata, flags, rc): global flag_connected flag_connected = 1def on_disconnect(client, userdata, rc): global flag_connected flag_connected = 0client = mqtt.Client()client.on_connect = on_connectclient.on_disconnect = on_disconnectclient.connect(server,port)client.loop_forever()if flag_connected == 1: # Publish messageelse: # Wait to reconnect
