from PyQt5 import QtCore, QtGui, QtWidgets
from test import Ui_Dialog
from Login import Ui_MainWindow_Login


class Ui_Dialog(QtWidgets.QWidget,Ui_Dialog):
  def __init__(self):
    super(Ui_Dialog,self).__init__()
    self.setupUi(self)
  #定义登出按钮的功能
  def logoutEvent(self):
    self.hide()      #隐藏此窗口
    self.log = loginWindow() 
    self.log.show()    #显示登录窗口
               #必须加上self

class loginWindow(QtWidgets.QMainWindow,Ui_MainWindow_Login):
  def __init__(self):
    super(loginWindow,self).__init__()
    self.setupUi(self)
  #定义登录按钮的功能
  def loginEvent(self):
    self.hide()
    self.dia = Ui_Dialog()
    self.dia.show()
    #self.dia.exec_()
    #pyqt5下show()方法有所改变，不再使用exec_()方法。

#运行窗口Login
if __name__=="__main__":
  import sys
  app=QtWidgets.QApplication(sys.argv)
  login_show=loginWindow()
  login_show.show()
  sys.exit(app.exec_())

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow_Login(object):
  def setupUi(self, MainWindow_Login):
    #略
  def retranslateUi(self, MainWindow_Login):
    #略

if __name__=="__main__":
  import sys
  app=QtWidgets.QApplication(sys.argv)
  widget = QtWidgets.QMainWindow()
  login = Ui_MainWindow_Login()
  login.setupUi(widget)
  widget.show()
  sys.exit(app.exec_())