Python 使用 Paho Mqtt 客户端发布和订阅
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Publish and Subscribe with Paho Mqtt Client
提问by Mohamed
After installing paho mqtt client on my raspberry pi and connecting my android application and arduino with my broker. I want after receiving message from the application or the arduino client republish this message to this clients for example if i recieve "ON" after i recieve "OFF", the next publish it will be "ON" "OFF" "ON" "OFF"... or i need to be just "ON" or "OFF"
在我的树莓派上安装 paho mqtt 客户端并将我的 android 应用程序和 arduino 与我的经纪人连接后。我希望在收到来自应用程序或 arduino 客户端的消息后，将此消息重新发布到此客户端，例如，如果我在收到“OFF”后收到“ON”，则下一次发布它将是“ON”“OFF”“ON”“OFF” “...或者我需要只是“开”或“关”
import paho.mqtt.client as mqtt
message = 'ON'
def on_connect(mosq, obj, rc):
print("rc: " + str(rc))
def on_message(mosq, obj, msg):
global message
print(msg.topic + " " + str(msg.qos) + " " + str(msg.payload))
message = msg.payload
def on_publish(mosq, obj, mid):
print("mid: " + str(mid))
def on_subscribe(mosq, obj, mid, granted_qos):
print("Subscribed: " + str(mid) + " " + str(granted_qos))
def on_log(mosq, obj, level, string):
print(string)
mqttc = mqtt.Client()
# Assign event callbacks
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_publish = on_publish
mqttc.on_subscribe = on_subscribe
# Connect
mqttc.connect("localhost", 1883,60)
# Start subscribe, with QoS level 0
mqttc.subscribe("f", 0)
# Publish a message
#mqttc.publish("hello/world", "my message")
# Continue the network loop, exit when an error occurs
rc = 0
while rc == 0:
rc = mqttc.loop()
mqttc.publish("f",message)
print("rc: " + str(rc))
回答by hardillb
OK,
好的，
The following code will subscribe on topic fand republish on topic f2
以下代码将订阅主题f并重新发布主题f2
import paho.mqtt.client as mqtt
message = 'ON'
def on_connect(mosq, obj, rc):
mqttc.subscribe("f", 0)
print("rc: " + str(rc))
def on_message(mosq, obj, msg):
global message
print(msg.topic + " " + str(msg.qos) + " " + str(msg.payload))
message = msg.payload
mqttc.publish("f2",msg.payload);
def on_publish(mosq, obj, mid):
print("mid: " + str(mid))
def on_subscribe(mosq, obj, mid, granted_qos):
print("Subscribed: " + str(mid) + " " + str(granted_qos))
def on_log(mosq, obj, level, string):
print(string)
mqttc = mqtt.Client()
# Assign event callbacks
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_publish = on_publish
mqttc.on_subscribe = on_subscribe
# Connect
mqttc.connect("localhost", 1883,60)
# Continue the network loop
mqttc.loop_forever()
回答by rishav
i think this may help you .
我想这可能对你有帮助。
import threading
import paho.mqtt.client as mqtt
def publish_1(client,topic):
message="on"
print("publish data")
client.publish(topic,message)
publish_1(client,topic)
broker="test.mosquitto.org"
topic_pub='/temperature123'
topic_sub='$SYS/#'
def on_connect(client, userdata, rc):
print("Connected with result code "+str(rc))
client.subscribe(topic_sub)
def on_message(client, userdata, msg):
print(msg.topic+" "+str(msg.payload))
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect(broker, 1883, 60)
thread1=threading.Thread(target=publish_1,args=(client,topic_pub))
thread1.start()
client.loop_forever()
this program uses threading and pass client object. but problem with this that this publish recursively.
该程序使用线程并传递客户端对象。但是这个问题是递归发布的。
回答by Anurag Gupta
you can study this code and use it for yourself,
你可以研究这段代码并自己使用，
import RPi.GPIO as GPIO
import time
import paho.mqtt.client as mqtt
GPIO.setmode(GPIO.BOARD)
GPIO.setup(13,GPIO.IN)
mqttc=mqtt.Client()
mqttc.connect("iot.eclipse.org",1883,60)
mqttc.loop_start()
def reading1():
a=GPIO.input(13)
print(a)
return a
while 1:
t=reading1()
(result,mid)=mqttc.publish("paho/temp_ab",t,2)
time.sleep(1)
mqttc.loop_stop()
mqttc.disconnect()
