构造线程的信息函数，定时发送信号, 将时间信息器绑定函数,实现定时执行的操作

Counter.py 

"""
使用线程类(QThread)编写计数器

QThread

def run(self):
    while True:
        self.sleep(1)
        if sec == 5:
            break;
QLCDNumber

WorkThread(QThread)
用到自定义信号
"""
from PyQt5.QtWidgets import *
from PyQt5.QtCore import QTimer, QDateTime
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys

sec = 0

class WorkThread(QThread):
    timer = pyqtSignal() #每隔一秒发送一次信号
    end = pyqtSignal() #计数完成后发送一次信号
    def run(self):
        while True:
            self.sleep(1)  #休眠一秒
            if sec == 5:
                self.end.emit() #发送end信号
                break
            self.timer.emit() #发送timer信号
class Counter(QWidget):

    def __init__(self):
        super(Counter, self).__init__()

        self.setWindowTitle("使用线程类(QThread)编写计数器")
        self.resize(300, 120)

        layout = QVBoxLayout()
        self.lcdNumber = QLCDNumber()
        layout.addWidget(self.lcdNumber)

        button = QPushButton('开始计数')
        layout.addWidget(button)

        self.workThread = WorkThread()

        #将时间
        self.workThread.timer.connect(self.countTime)
        self.workThread.end.connect(self.end)
        button.clicked.connect(self.work)

        self.setLayout(layout)

    #定时显示数字
    def countTime(self):
        global sec
        sec += 1
        self.lcdNumber.display(sec)

    #结束后做窗口的显示
    def end(self):
        QMessageBox.information(self, "消息", "计数结束", QMessageBox.Ok)

    def work(self):
        self.workThread.start() #将线程进行启动


if __name__ == "__main__":
    app = QApplication(sys.argv)
    main = Counter()
    main.show()

    sys.exit(app.exec_())