pyqt5 progressbar

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QProgressBar, QPushButton

class ProgressBarDemo(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setWindowTitle('ProgressBar Demo')
        self.setGeometry(300, 300, 300, 200)

        layout = QVBoxLayout()

        self.progressBar = QProgressBar(self)
        self.progressBar.setMinimum(0)
        self.progressBar.setMaximum(100)
        layout.addWidget(self.progressBar)

        self.button = QPushButton('Start', self)
        self.button.clicked.connect(self.startProgress)
        layout.addWidget(self.button)

        self.setLayout(layout)

    def startProgress(self):
        for i in range(101):
            self.progressBar.setValue(i)
            QApplication.processEvents()  # 更新界面

if __name__ == '__main__':
    app = QApplication(sys.argv)
    demo = ProgressBarDemo()
    demo.show()
    sys.exit(app.exec_())