线程完成后如何更新小部件答案

【问题标题】：How to update widgets after thread completed线程完成后如何更新小部件
【发布时间】：2017-07-02 14:43:45
【问题描述】：

下面的代码创建了一个带有标签和按钮的对话框。按下按钮调用onClick 函数，该函数将calculate 函数作为任务放入queue，触发thread 来完成这项工作。

线程完成后，我想调用dialog.onThreadCompleted 方法，将计算结果作为参数传递给它。然后，此方法将使用thread 执行的计算结果更新self.label。如何实现？

import threading
import Queue as Queue
import functools

global queue
queue = Queue.Queue()


class Thread(QThread):
    def __init__(self, parent=None):
        QThread.__init__(self, parent)

    def run(self):
        global queue
        while True:
            partial = queue.get()
            output = partial()
            queue.task_done()


threads = []
thread = Thread()
threads.append(thread)
thread.start()


def calculate(number):
    for i in range(number):
        i += i
    print 'calculate completed. result: %s' % i
    return i


class Dialog(QDialog):
    def __init__(self, parent=None):
        QDialog.__init__(self, parent)
        self.setLayout(QVBoxLayout())
        self.label = QLabel(self)
        self.label.setText('This label should display result')
        self.layout().addWidget(self.label)
        button = QPushButton('Start process')
        button.clicked.connect(self.onClick)
        self.layout().addWidget(button)

    def onThreadCompleted(self, result):
        self.label.setText(str(result))

    def onClick(self):
        self.label.setText('Calculation is starting...')
        partial = functools.partial(calculate, number=100000000)
        queue.put(partial)

if __name__ == '__main__':
    app = QApplication([])
    dialog = Dialog()
    dialog.show()
    qApp.exec_()

【问题讨论】：

标签： python multithreading qt pyqt multiprocessing

【解决方案1】：

我决定修改您的代码以便仅使用PyQt（没有Queue 或Thread，只有QThread）。我希望代码是不言自明的。如果没有，请问:)

from PyQt4 import QtCore, QtGui
from PyQt4.QtGui import QDialog
from PyQt4.QtGui import *

import sys

class Thread(QtCore.QObject):
    finished = QtCore.pyqtSignal()

    def __init__(self, parent=None):
        QtCore.QObject.__init__(self, parent)

        self.TheWorker = QtCore.QThread()
        self.moveToThread(self.TheWorker)
        self.TheWorker.start()

        self.number = 0

    def calculate(self):
        num = 10000
        for i in range(num):
            self.number += i
        print 'calculate completed. result: %s' % self.number
        self.finished.emit()

class Dialog(QDialog):
    def __init__(self, parent=None):
        QDialog.__init__(self, parent)

        # worker which will do the job or you on different thread
        self.myWorker = Thread()
        # catched signal about finishing the job and calls desired method
        self.myWorker.finished.connect(self.onThreadCompleted)

        self.setLayout(QVBoxLayout())
        self.label = QLabel(self)
        self.label.setText('This label should display result')
        self.layout().addWidget(self.label)
        button = QPushButton('Start process')
        button.clicked.connect(self.myWorker.calculate)
        self.layout().addWidget(button)

    def onThreadCompleted(self):
        self.label.setText(str(self.myWorker.number))

    # to quit the thread properly
    def quitThread(self):
        self.myWorker.TheWorker.quit()
        self.myWorker.TheWorker.wait()

if __name__ == '__main__':
    app = QApplication([])
    dialog = Dialog()
    dialog.show()
    qApp.exec_()
    dialog.quitThread()
    sys.exit()

【讨论】：