[英]Use paho-mqtt with PyQt
如何使用 QThread 的回調函數?
回調函數 on_message 不打印任何數據。 在 run() 中,我連接到 mqtt-broker 並訂閱主題。 當我收到新消息時,on_message 必須工作。
示例簡單的 QT 應用程序。 改變值事件與簡單的 QLCD 相連。 訂閱主題取自儀表板
#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtCore import Qt, QThread, pyqtSignal
from PyQt5.QtWidgets import (QWidget, QLCDNumber, QSlider,
QVBoxLayout, QApplication)
from random import uniform, normalvariate, randint
import time
import paho.mqtt.client as mqtt
import paho.mqtt.subscribe as subscribe
class Example(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
lcd = QLCDNumber(self)
self.data=DataThread()
vbox = QVBoxLayout()
vbox.addWidget(lcd)
self.setLayout(vbox)
self.data.valueChanged.connect(lcd.display)
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('Callback')
self.data.start()
self.show()
class DataThread(QThread):
valueChanged = pyqtSignal(object)
val=0
def on_message(mqttc, obj, msg):
mstr=msg.payload.decode("ascii")
val=mstr
self.valueChanged.emit(val)
def on_subscribe(mqttc, obj, mid, granted_qos):
print("Subscribed: "+str(mid)+" "+str(granted_qos))
def run(self):
msg = subscribe.simple("shok2", hostname="broker.hivemq.com")
print("%s %s" % (msg.topic, msg.payload))
mqttc = mqtt.Client()
mqttc.on_subscribe = self.on_subscribe
mqttc.on_message = self.on_message
mqttc.connect("broker.hivemq.com")
print("subsrcibe")
mqttc.subscribe("shok2")
mqttc.loop_forever()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
沒必要用線程,按照Qt的邏輯:讓我們用信號。 在下面的代碼中,我展示了我正在實現的 MQTT 客戶端庫的進展,至少到目前為止實現了你想要的,在接下來的幾天我將添加更多功能。
from PyQt5 import QtCore, QtWidgets
import paho.mqtt.client as mqtt
class MqttClient(QtCore.QObject):
Disconnected = 0
Connecting = 1
Connected = 2
MQTT_3_1 = mqtt.MQTTv31
MQTT_3_1_1 = mqtt.MQTTv311
connected = QtCore.pyqtSignal()
disconnected = QtCore.pyqtSignal()
stateChanged = QtCore.pyqtSignal(int)
hostnameChanged = QtCore.pyqtSignal(str)
portChanged = QtCore.pyqtSignal(int)
keepAliveChanged = QtCore.pyqtSignal(int)
cleanSessionChanged = QtCore.pyqtSignal(bool)
protocolVersionChanged = QtCore.pyqtSignal(int)
messageSignal = QtCore.pyqtSignal(str)
def __init__(self, parent=None):
super(MqttClient, self).__init__(parent)
self.m_hostname = ""
self.m_port = 1883
self.m_keepAlive = 60
self.m_cleanSession = True
self.m_protocolVersion = MqttClient.MQTT_3_1
self.m_state = MqttClient.Disconnected
self.m_client = mqtt.Client(clean_session=self.m_cleanSession,
protocol=self.protocolVersion)
self.m_client.on_connect = self.on_connect
self.m_client.on_message = self.on_message
self.m_client.on_disconnect = self.on_disconnect
@QtCore.pyqtProperty(int, notify=stateChanged)
def state(self):
return self.m_state
@state.setter
def state(self, state):
if self.m_state == state: return
self.m_state = state
self.stateChanged.emit(state)
@QtCore.pyqtProperty(str, notify=hostnameChanged)
def hostname(self):
return self.m_hostname
@hostname.setter
def hostname(self, hostname):
if self.m_hostname == hostname: return
self.m_hostname = hostname
self.hostnameChanged.emit(hostname)
@QtCore.pyqtProperty(int, notify=portChanged)
def port(self):
return self.m_port
@port.setter
def port(self, port):
if self.m_port == port: return
self.m_port = port
self.portChanged.emit(port)
@QtCore.pyqtProperty(int, notify=keepAliveChanged)
def keepAlive(self):
return self.m_keepAlive
@keepAlive.setter
def keepAlive(self, keepAlive):
if self.m_keepAlive == keepAlive: return
self.m_keepAlive = keepAlive
self.keepAliveChanged.emit(keepAlive)
@QtCore.pyqtProperty(bool, notify=cleanSessionChanged)
def cleanSession(self):
return self.m_cleanSession
@cleanSession.setter
def cleanSession(self, cleanSession):
if self.m_cleanSession == cleanSession: return
self.m_cleanSession = cleanSession
self.cleanSessionChanged.emit(cleanSession)
@QtCore.pyqtProperty(int, notify=protocolVersionChanged)
def protocolVersion(self):
return self.m_protocolVersion
@protocolVersion.setter
def protocolVersion(self, protocolVersion):
if self.m_protocolVersion == protocolVersion: return
if protocolVersion in (MqttClient.MQTT_3_1, MQTT_3_1_1):
self.m_protocolVersion = protocolVersion
self.protocolVersionChanged.emit(protocolVersion)
#################################################################
@QtCore.pyqtSlot()
def connectToHost(self):
if self.m_hostname:
self.m_client.connect(self.m_hostname,
port=self.port,
keepalive=self.keepAlive)
self.state = MqttClient.Connecting
self.m_client.loop_start()
@QtCore.pyqtSlot()
def disconnectFromHost(self):
self.m_client.disconnect()
def subscribe(self, path):
if self.state == MqttClient.Connected:
self.m_client.subscribe(path)
#################################################################
# callbacks
def on_message(self, mqttc, obj, msg):
mstr = msg.payload.decode("ascii")
# print("on_message", mstr, obj, mqttc)
self.messageSignal.emit(mstr)
def on_connect(self, *args):
# print("on_connect", args)
self.state = MqttClient.Connected
self.connected.emit()
def on_disconnect(self, *args):
# print("on_disconnect", args)
self.state = MqttClient.Disconnected
self.disconnected.emit()
class Widget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Widget, self).__init__(parent)
lay = QtWidgets.QVBoxLayout(self)
self.lcd_number = QtWidgets.QLCDNumber()
lay.addWidget(self.lcd_number)
self.client = MqttClient(self)
self.client.stateChanged.connect(self.on_stateChanged)
self.client.messageSignal.connect(self.on_messageSignal)
self.client.hostname = "broker.hivemq.com"
self.client.connectToHost()
@QtCore.pyqtSlot(int)
def on_stateChanged(self, state):
if state == MqttClient.Connected:
print(state)
self.client.subscribe("shok2")
@QtCore.pyqtSlot(str)
def on_messageSignal(self, msg):
try:
val = float(msg)
self.lcd_number.display(val)
except ValueError:
print("error: Not is number")
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = Widget()
w.show()
sys.exit(app.exec_())
基於這個答案,我創建了一個庫來使用 PyQt5 和 PySide2 的 paho: https : //github.com/eyllanesc/qtmqtt
您是否必須創建方法 on_connect 使用訂閱 on_connect 方法而不是運行。
def on_connect(self, client, userdata, flags, rc):
print "Connected", rc
client.subscribe("shok2")
def run(self):
msg = subscribe.simple("shok2", hostname="broker.hivemq.com")
print("%s %s" % (msg.topic, msg.payload))
mqttc = mqtt.Client()
mqttc.on_subscribe = self.on_subscribe
mqttc.on_message = self.on_message
mqttc.on_connect = on_connect
mqttc.connect("broker.hivemq.com")
mqttc.loop_forever()
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