PyQt5系列教程(十)分离UI主线程与耗时子线程

本文主要是介绍PyQt5系列教程(十)分离UI主线程与耗时子线程，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

原文出处: https://xugaoxiang.com/2019/12/04/pyqt5-8-main-sub-thread/

软硬件环境

windows 10 64bit
PyQt5
Anaconda3 with python 3.6.5

前言

在做界面开发时，无论是移动端的Android，还是我们这里讲的PyQt5，经常会有一个界面开发准则，那就是UI主线程与耗时子线程一定要分开，主线程负责刷新界面，耗时操作，如网络交互、磁盘IO等，都应该放在子线程里执行，它们各司其职，保证系统正常运行，提升整体用户体验。

实例代码

首先看下工程目录结构

main.py，这是工程入口文件，它负责创建app

# -*- coding: utf-8 -*-"""
@author: Xu Gaoxiang
@license: Apache V2
@email: xugx.ai@gmail.com
@site: https://www.xugaoxiang.com
@software: PyCharm
@file: main.py
@time: 2019/1/10 10:50
"""import sysfrom PyQt5.QtWidgets import QApplicationfrom gui.mainwindow import MainWindowif __name__ == '__main__':app = QApplication(sys.argv)main_window = MainWindow()main_window.show()sys.exit(app.exec_())

ui_mainwindow.py，负责界面的绘制，这个文件通过designer图形化工具作图然后使用pyuic工具生成对应的python代码，可以参考之前的文章 https://blog.xugaoxiang.com/python/pyqt5-designer.html

# -*- coding: utf-8 -*-# Form implementation generated from reading ui file '.\mainwindow.ui'
#
# Created by: PyQt5 UI code generator 5.6
#
# WARNING! All changes made in this file will be lost!from PyQt5 import QtCore, QtGui, QtWidgetsclass Ui_MainWindow(object):def setupUi(self, MainWindow):MainWindow.setObjectName("MainWindow")MainWindow.resize(800, 600)MainWindow.setMinimumSize(QtCore.QSize(800, 600))MainWindow.setMaximumSize(QtCore.QSize(800, 600))self.centralwidget = QtWidgets.QWidget(MainWindow)self.centralwidget.setObjectName("centralwidget")self.button_ok = QtWidgets.QPushButton(self.centralwidget)self.button_ok.setGeometry(QtCore.QRect(260, 220, 230, 140))self.button_ok.setMinimumSize(QtCore.QSize(230, 140))self.button_ok.setMaximumSize(QtCore.QSize(230, 140))font = QtGui.QFont()font.setPointSize(50)self.button_ok.setFont(font)self.button_ok.setFocusPolicy(QtCore.Qt.TabFocus)self.button_ok.setObjectName("button_ok")MainWindow.setCentralWidget(self.centralwidget)self.statusbar = QtWidgets.QStatusBar(MainWindow)self.statusbar.setObjectName("statusbar")MainWindow.setStatusBar(self.statusbar)self.menubar = QtWidgets.QMenuBar(MainWindow)self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 23))self.menubar.setObjectName("menubar")self.menuFile = QtWidgets.QMenu(self.menubar)self.menuFile.setObjectName("menuFile")self.menuHelp = QtWidgets.QMenu(self.menubar)self.menuHelp.setObjectName("menuHelp")MainWindow.setMenuBar(self.menubar)self.actionExit = QtWidgets.QAction(MainWindow)self.actionExit.setObjectName("actionExit")self.actionCopy = QtWidgets.QAction(MainWindow)self.actionCopy.setObjectName("actionCopy")self.actionPaste = QtWidgets.QAction(MainWindow)self.actionPaste.setObjectName("actionPaste")self.actionCut = QtWidgets.QAction(MainWindow)self.actionCut.setObjectName("actionCut")self.actionHelp = QtWidgets.QAction(MainWindow)self.actionHelp.setObjectName("actionHelp")self.actionAbout = QtWidgets.QAction(MainWindow)self.actionAbout.setObjectName("actionAbout")self.action_query = QtWidgets.QAction(MainWindow)self.action_query.setObjectName("action_query")self.action_backupDB = QtWidgets.QAction(MainWindow)self.action_backupDB.setObjectName("action_backupDB")self.action_reset_mac = QtWidgets.QAction(MainWindow)self.action_reset_mac.setObjectName("action_reset_mac")self.menuFile.addSeparator()self.menuFile.addAction(self.actionExit)self.menuFile.addSeparator()self.menuHelp.addSeparator()self.menuHelp.addSeparator()self.menuHelp.addAction(self.actionAbout)self.menuHelp.addSeparator()self.menubar.addAction(self.menuFile.menuAction())self.menubar.addAction(self.menuHelp.menuAction())self.retranslateUi(MainWindow)QtCore.QMetaObject.connectSlotsByName(MainWindow)def retranslateUi(self, MainWindow):_translate = QtCore.QCoreApplication.translateMainWindow.setWindowTitle(_translate("MainWindow", "分离UI主线程和工作线程"))self.button_ok.setText(_translate("MainWindow", "确定"))self.menuFile.setTitle(_translate("MainWindow", "File"))self.menuHelp.setTitle(_translate("MainWindow", "Help"))self.actionExit.setText(_translate("MainWindow", "退出"))self.actionHelp.setText(_translate("MainWindow", "软件使用说明"))self.actionAbout.setText(_translate("MainWindow", "关于"))

mainwindow.py，主要负责界面上控件的事件处理

"""
@author: Xu Gaoxiang
@license: Apache V2
@email: xugx.ai@gmail.com
@site: https://www.xugaoxiang.com
@software: PyCharm
@file: mainwindow.py
@time: 2019/1/10 10:49
"""import timefrom PyQt5.QtWidgets import QMainWindowfrom gui.ui_mainwindow import *class MainWindow(QMainWindow, Ui_MainWindow):def __init__(self, parent=None):super(MainWindow, self).__init__(parent)self.setupUi(self)# 绑定点击事件self.button_ok.clicked.connect(self.button_start)def button_start(self):self.button_ok.setChecked(True)self.button_ok.setDisabled(True)time.sleep(20)

这里我们使用time.sleep(20)来模拟耗时任务，执行python main.py后一会，界面就会出现无响应，假死的现象，等到20秒过后，界面又恢复了正常，用户体验非常差。

其实要解决这个问题，也非常简单。我们将UI主线程中的time.sleep(20)移动到子线程中就可以了。PyQt5中提供了线程类QThread，我们继承它并重写它的run方法，新建一个新的文件threads.py

# -*- coding: utf-8 -*-"""
@author: Xu Gaoxiang
@license: Apache V2
@email: xugx.ai@gmail.com
@site: https://www.xugaoxiang.com
@software: PyCharm
@file: threads.py
@time: 2019/1/10 11:03
"""import timefrom PyQt5.QtCore import QThread, pyqtSignalclass WorkThread(QThread):# 使用信号和UI主线程通讯，参数是发送信号时附带参数的数据类型，可以是str、int、list等finishSignal = pyqtSignal(str)# 带参数示例def __init__(self,  ip, port, parent=None):super(WorkThread, self).__init__(parent)self.ip = ipself.port = portdef run(self):'''重写'''print('=============sleep======ip: {}, port: {}'.format(self.ip, self.port))time.sleep(20)self.finishSignal.emit('This is a test.')return

注意到这里我们使用了pyqtSignal，我们使用它来跟UI主线程通讯，一般用于界面元素的刷新，在子线程的最后，我们发送这个信号。

对应的mainwindow.py，需要进行如下修改


from gui.threads import WorkThread# 其它部分省略
def button_start(self):print('button_start clicked.')# 设置按钮不可用self.button_ok.setChecked(True)self.button_ok.setDisabled(True)self.th = WorkThread(ip='192.168.1.1', port=4000)# 将线程th的信号finishSignal和UI主线程中的槽函数button_finish进行连接self.th.finishSignal.connect(self.button_finish)# 启动线程self.th.start()def button_finish(self, msg):print('msg: {}'.format(msg))# 设置按钮可用self.button_ok.setChecked(False)self.button_ok.setDisabled(False)