pyqt5实现开始按钮开始一个循环，结束按钮结束循环

part 1

初学pyqt，折腾了好久才把功能实现，功能是按开始按钮循环输出数字在textBrowser控件中，按结束按钮停止输出，再按开始按钮重新开始循环

part 2

技术点与其中遇到的坑
1、遇到的坑：一开始想实现按结束按钮停止循环，结果按了开始就一直结束不了，开始是在Ui_Dialog里写了个函数弄了个标志位想要结束，结果那个标志位根本作用不了开始循环的标志位，所以想到用线程来实现，就是界面这个主线程开始一个循环的子线程，按停止按钮结束循环的子线程。百度了好多，用threading和QThread都可以实现，重点是要用信号槽机制才能将标识位的值改变。

2、将thread中的输出显示在界面主线程中的textBrowser中
Ui_Dialog相关代码

self.myThread1.strsin.connect(self.updateText)
  
def updateText(self,text):
        self.textBrowser.append(text)

myThread相关代码

strsin = pyqtSignal(str)
self.strsin.emit(str(i))

3、通过信号槽机制使线程停止
Ui_Dialog相关代码

sin = pyqtSignal()
self.myThread1 = myThread()
self.sin.connect(self.myThread1.stop)

myThread相关代码

def stop(self):
        self.flag = 0

4、点击按钮传参
实现将按钮的text传入函数

self.startButton.clicked.connect(lambda:self.startOrstop(self.startButton.text()))

part 3

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'myWindow.ui'
#
# Created by: PyQt5 UI code generator 5.13.1
#
# WARNING! All changes made in this file will be lost!


from PyQt5 import QtCore, QtWidgets
from PyQt5.QtCore import QThread,pyqtSignal,QObject
from PyQt5.QtWidgets import QApplication,QMainWindow
import time,sys


class Ui_Dialog(QObject):

    sin = pyqtSignal()

    def __init__(self):


        super(Ui_Dialog,self).__init__()
        self.myThread1 = myThread()
        self.sin.connect(self.myThread1.stop)
        self.myThread1.strsin.connect(self.updateText)


    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(593, 415)
        self.startButton = QtWidgets.QPushButton(Dialog)
        self.startButton.setGeometry(QtCore.QRect(410, 80, 75, 23))
        self.startButton.setObjectName("pushButton")
        self.stopButton = QtWidgets.QPushButton(Dialog)
        self.stopButton.setGeometry(QtCore.QRect(410, 140, 75, 23))
        self.stopButton.setObjectName("pushButton_2")
        self.textBrowser = QtWidgets.QTextBrowser(Dialog)
        self.textBrowser.setGeometry(QtCore.QRect(50, 120, 256, 192))
        self.textBrowser.setObjectName("textBrowser")

        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

        self.update_tag = 1
                                                self.startButton.clicked.connect(lambda:self.startOrstop(self.startButton.text()))
                self.stopButton.clicked.connect(lambda:self.startOrstop(self.stopButton.text()))




    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.startButton.setText(_translate("Dialog", "start"))
        self.stopButton.setText(_translate("Dialog", "stop"))

    def startOrstop(self,text):
        try:
            print(text)
            myThread1 = myThread()
            self.sin.connect(myThread1.stop)

            if text =='start':
                self.update_tag = 0
                self.textBrowser.clear()
                self.myThread1.flag = 1
                self.myThread1.start()
            elif text == 'stop':
                self.update_tag = 1
                self.sin.emit()
        except Exception as e:
            print(e)


    def updateText(self,text):
        self.textBrowser.append(text)




class myThread(QThread):

    strsin = pyqtSignal(str)

    def __init__(self,parent=None):
        super(myThread,self).__init__(parent)
        self.flag = 1

    def run(self):
        try:
            for i in range(100):
                if self.flag == 1:
                    self.strsin.emit(str(i))
                    time.sleep(0.1)
                    QtWidgets.QApplication.processEvents()
                elif self.flag == 0:
                    self.strsin.emit("stop thread")
                    break
            self.strsin.emit("please restart")
        except Exception as e:
            print(e)


    def stop(self):
        self.flag = 0


if __name__ == "__main__":
    app = QApplication(sys.argv)
    MainWindow = QMainWindow()
    ui_dialog = Ui_Dialog()
    ui_dialog.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

part 4

功能展示