import paho.mqtt.client as mqtt  
import time  
  
# MQTT服務(wù)器地址  
broker_address = "localhost"  # 替換為你的MQTT代理地址  
port = 1883  # MQTT代理的端口，默認為1883  
client_id = "python_mqtt_client"  # MQTT客戶端的唯一ID  
topic = "test/topic"  # 要發(fā)布和訂閱的主題  
username = "your_username"  # MQTT代理的用戶名  
password = "your_password"  # MQTT代理的密碼  
  
# 當(dāng)連接到MQTT代理時調(diào)用的回調(diào)函數(shù)  
def on_connect(client, userdata, flags, rc):  
    print(f"Connected with result code {rc}")  
    # 訂閱主題  
    client.subscribe(topic)  
  
# 當(dāng)接收到MQTT消息時調(diào)用的回調(diào)函數(shù)  
def on_message(client, userdata, msg):  
    print(f"Received message '{msg.payload.decode('utf-8')}' on topic '{msg.topic}' with QoS {msg.qos}")  
  
# 創(chuàng)建MQTT客戶端實例  
client = mqtt.Client(client_id)  
  
# 設(shè)置用戶名和密碼  
client.username_pw_set(username, password)  
  
# 為客戶端設(shè)置回調(diào)函數(shù)  
client.on_connect = on_connect  
client.on_message = on_message  
  
# 連接到MQTT代理  
client.connect(broker_address, port)  
  
# 開始網(wǎng)絡(luò)循環(huán)，處理接收到的消息和重連  
client.loop_start()  
  
try:  
    print("Publishing message...")  
    # 發(fā)布一條消息  
    client.publish(topic, "Hello, MQTT with username and password!", qos=1)  
      
    # 等待用戶輸入，以保持程序運行并接收消息  
    print("Press Enter to exit...")  
    input()  
except KeyboardInterrupt:  
    pass  
finally:  
    # 停止網(wǎng)絡(luò)循環(huán)并斷開連接  
    client.loop_stop()  
    client.disconnect()  
    print("Disconnected from MQTT broker.")