pyqt4 利用信号槽在子线程里面操作Qt界面

#-*- coding:utf-8 -*-
#######
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import sys
import time
import threading
class MyWindow(QDialog,QWidget):
sigSetTime = pyqtSignal(str)  ####信号定义
def __init__(self,parent = None):
super(MyWindow,self).__init__(parent)
self.setFont(QFont("Roman times",14))#####设置字体
self.resize(200,50)
self.mainlayout = QGridLayout(self)
self.timeLabel = QLabel()
self.timeLabel.setText(u"时间：")
self.mainlayout.addWidget(self.timeLabel,0,0,1,1)
self.timeLineEdit = QLineEdit()
self.mainlayout.addWidget(self.timeLineEdit,0,1,1,1)
self.sigSetTime.connect(self.setTime)####信号槽连接
t = threading.Thread(target = self.getTimeAndSetTime,args=(self.sigSetTime,))
t.setDaemon(True)
t.start()

def setTime(self,str_time):
self.timeLineEdit.setText(str_time)

def getTimeAndSetTime(self,setTimeSignal):
while True:
setTimeSignal.emit(str(time.localtime().tm_hour)+":"+ str(time.localtime().tm_min) + ":" + str(time.localtime().tm_sec))######信号换发
time.sleep(1)

app=QApplication(sys.argv)
window=MyWindow()
window.show()
app.exec_()