pyqt5 主界面打开新主界面、打开Dialog、打开提示框的实现模板

 import sys
 from PyQt5.QtWidgets import *
 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 ################################################
 #######创建主窗口
 ################################################
 class FirstMainWindow(QMainWindow):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.setWindowTitle('主界面')

         ###### 创建界面 ######
         self.centralwidget = QWidget()
         self.setCentralWidget(self.centralwidget)
         self.Layout = QVBoxLayout(self.centralwidget)

         # 设置顶部三个按钮
         self.topwidget = QWidget()
         self.Layout.addWidget(self.topwidget)
         self.buttonLayout = QHBoxLayout(self.topwidget)

         self.pushButton1 = QPushButton()
         self.pushButton1.setText("打开主界面")
         self.buttonLayout.addWidget(self.pushButton1)

         self.pushButton2 = QPushButton()
         self.pushButton2.setText("打开对话框")
         self.buttonLayout.addWidget(self.pushButton2)

         self.pushButton3 = QPushButton()
         self.pushButton3.setText("打开提示框")
         self.buttonLayout.addWidget(self.pushButton3)

         # 设置中间文本
         self.label = QLabel()
         self.label.setText("第一个主界面")
         self.label.setSizePolicy(QSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding))
         self.label.setAlignment(Qt.AlignCenter)
         self.label.setFont(QFont("Roman times", 50, QFont.Bold))
         self.Layout.addWidget(self.label)

         # 设置状态栏
         self.statusBar().showMessage("当前用户：一心狮")

         # 窗口最大化
         self.showMaximized()

         ###### 三个按钮事件 ######
         self.pushButton1.clicked.connect(self.on_pushButton1_clicked)
         self.pushButton2.clicked.connect(self.on_pushButton2_clicked)
         self.pushButton3.clicked.connect(self.on_pushButton3_clicked)

     # 按钮一：打开主界面
     windowList = []
     def on_pushButton1_clicked(self):
         the_window =SecondWindow()
         self.windowList.append(the_window)   ##注：没有这句，是不打开另一个主界面的！
         self.close()
         the_window.show()

     # 按钮二：打开对话框
     def on_pushButton2_clicked(self):
         the_dialog = TestdemoDialog()
         if the_dialog.exec_() == QDialog.Accepted:
             pass

     # 按钮三：打开提示框
     def on_pushButton3_clicked(self):
         QMessageBox.information(self, "提示", "这是information框！")
         #QMessageBox.question(self, "提示", "这是question框！")
         #QMessageBox.warning(self, "提示", "这是warning框！")
         #QMessageBox.about(self, "提示", "这是about框！")

 ################################################
 #######第二个主界面
 ################################################
 class SecondWindow(QMainWindow):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.setWindowTitle('第二主界面')

         # 设置中间文本
         self.label = QLabel()
         self.label.setText("第二个主界面")
         self.label.setSizePolicy(QSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding))
         self.label.setAlignment(Qt.AlignCenter)
         self.label.setFont(QFont("Roman times", 50, QFont.Bold))
         self.setCentralWidget(self.label)

         # 设置状态栏
         self.statusBar().showMessage("当前用户：一心狮")

         # 窗口最大化
         self.showMaximized()

     ###### 重写关闭事件，回到第一界面
     windowList = []
     def closeEvent(self, event):
         the_window = FirstMainWindow()
         self.windowList.append(the_window)  ##注：没有这句，是不打开另一个主界面的！
         the_window.show()
         event.accept()

 ################################################
 #######对话框
 ################################################
 class TestdemoDialog(QDialog):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.setWindowTitle('对话框')

         ### 设置对话框类型
         self.setWindowFlags(Qt.Tool)

 ################################################
 #######程序入门
 ################################################
 if __name__ == "__main__":
     app = QApplication(sys.argv)
     the_mainwindow = FirstMainWindow()
     the_mainwindow.show()
     sys.exit(app.exec_())