如何在 PyQt 中的两个窗口之间进行通信或切换？答案

【问题标题】：How to communicate or switch between two windows in PyQt?如何在 PyQt 中的两个窗口之间进行通信或切换？
【发布时间】：2012-03-30 03:36:18
【问题描述】：

我正在使用 python 和 Qt 开发一个应用程序。

我使用 Qt 设计了 2 个主窗口，即..QMainWindow（不是 QWidget 或 QDialog）。

顺其自然。

1.LoginWindow -- LoginUI(Qt)

2.StuffWindow --- StuffUI

首先我应该显示登录窗口。

然后我应该将用户名传递给 StaffWindow（管理东西需要用户名）

应显示员工窗口并关闭登录窗口..

我怎样才能做到这一点..？帮帮我..

【问题讨论】：

标签： python pyqt pyqt4 pyqt5 signals-slots

【解决方案1】：

匹配用户名和密码。

import sys
from PyQt5 import QtGui, QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication, QDialog, QDialogButtonBox, QFormLayout, QLabel, QLineEdit, QWidget, QVBoxLayout, QMessageBox

class LoginDialog(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(LoginDialog, self).__init__(parent)

        self.username = QLineEdit()
        self.password = QLineEdit()
        loginLayout = QFormLayout()
        loginLayout.addRow("Username", self.username)
        loginLayout.addRow("Password", self.password)

        self.buttons = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
        self.buttons.accepted.connect(self.check)
        self.buttons.rejected.connect(self.reject)

        layout = QVBoxLayout()
        layout.addLayout(loginLayout)
        layout.addWidget(self.buttons)
        self.setLayout(layout)

    def check(self):
        if str(self.username.text()) == "foo" and str(self.password.text()) == "bar": # do actual login check
            self.accept()
        else:
            QMessageBox.warning(
                self, 'Error', 'Bad user or password')
            pass # or inform the user about bad username/password

    def my_exception_hook(exctype, value, traceback):
        # Print the error and traceback
        print(exctype, value, traceback)
        # Call the normal Exception hook after
        sys._excepthook(exctype, value, traceback)
        sys.exit(1)

    # Back up the reference to the exceptionhook
    sys._excepthook = sys.excepthook

    # Set the exception hook to our wrapping function
    sys.excepthook = my_exception_hook


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        self.label = QLabel()
        self.setCentralWidget(self.label)

    def setUsername(self, username):
        # do whatever you want with the username
        self.username = username
        self.label.setText("%s%s%s" % ("Username entered: ", self.username, "\npassword ok!"))


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

    login = LoginDialog()
    if not login.exec_(): # 'reject': user pressed 'Cancel', so quit
        sys.exit(-1)      # instead of -1 another action can be triggered here.     

    # 'accept': continue
    main = MainWindow()

    # get the username, and supply it to main window
    main.setUsername(login.username.text())
    main.show()

    sys.exit(app.exec_())

【讨论】：

【解决方案2】：

这是Avaris 的PyQt5 更新版本。添加了一些异常处理以显示如何捕获一些错误（在编写代码时。享受吧！

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Ref to this OP question. https://stackoverflow.com/questions/9689053/how-to-communicate-or-switch-between-two-windows-in-pyqt4

import sys
from PyQt5 import QtGui, QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication, QDialog, QDialogButtonBox, QFormLayout, QLabel, QLineEdit, QWidget, QVBoxLayout

class LoginDialog(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(LoginDialog, self).__init__(parent)

        self.username = QLineEdit()
        self.password = QLineEdit()
        loginLayout = QFormLayout()
        loginLayout.addRow("Username", self.username)
        loginLayout.addRow("Password", self.password)

        self.buttons = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
        self.buttons.accepted.connect(self.check)
        self.buttons.rejected.connect(self.reject)

        layout = QVBoxLayout()
        layout.addLayout(loginLayout)
        layout.addWidget(self.buttons)
        self.setLayout(layout)

    def check(self):
        if str(self.password.text()) == "12345": # do actual login check
            self.accept()
        else:
            pass # or inform the user about bad username/password

    def my_exception_hook(exctype, value, traceback):
        # Print the error and traceback
        print(exctype, value, traceback)
        # Call the normal Exception hook after
        sys._excepthook(exctype, value, traceback)
        sys.exit(1)

    # Back up the reference to the exceptionhook
    sys._excepthook = sys.excepthook

    # Set the exception hook to our wrapping function
    sys.excepthook = my_exception_hook


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        self.label = QLabel()
        self.setCentralWidget(self.label)

    def setUsername(self, username):
        # do whatever you want with the username
        self.username = username
        self.label.setText("Username entered: %s" % self.username)


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

    login = LoginDialog()
    if not login.exec_(): # 'reject': user pressed 'Cancel', so quit
        sys.exit(-1)      # instead of -1 another action can be triggered here.     

    # 'accept': continue
    main = MainWindow()

    # get the username, and supply it to main window
    main.setUsername(login.username.text())
    main.show()

    sys.exit(app.exec_())

【讨论】：

【解决方案3】：

虽然这与您的问题没有直接关系，但您应该始终为密码字段设置 QLineEdit.EchoMode，如下所示（请参阅here）：

self.password.setEchoMode(QtGui.QLineEdit.Password)

【讨论】：

在“我忘记设置这个值”列表中确实有点离题，但 100% 切题。

【解决方案4】：

我同意jdi 提出的大部分观点，但我更喜欢稍微不同的方法。

LoginWindow 应该是以 MODAL 开头的 QDialog。
检查exec_()（即accept/reject）的返回以进行登录或取消/退出。
检查LoginWindow里面的登录
如果登录成功，使用提供的参数启动MainWindow

在看到 jdi 的答案之前，我开始编写一个简单的示例。我不妨把它放在这里。

import sys
from PyQt4 import QtGui, QtCore

class LoginDialog(QtGui.QDialog):
    def __init__(self, parent=None):
        super(LoginDialog, self).__init__(parent)

        self.username = QtGui.QLineEdit()
        self.password = QtGui.QLineEdit()
        loginLayout = QtGui.QFormLayout()
        loginLayout.addRow("Username", self.username)
        loginLayout.addRow("Password", self.password)

        self.buttons = QtGui.QDialogButtonBox(QtGui.QDialogButtonBox.Ok | QtGui.QDialogButtonBox.Cancel)
        self.buttons.accepted.connect(self.check)
        self.buttons.rejected.connect(self.reject)

        layout = QtGui.QVBoxLayout()
        layout.addLayout(loginLayout)
        layout.addWidget(self.buttons)
        self.setLayout(layout)

    def check(self):
        if str(self.password.text()) == "12345": # do actual login check
            self.accept()
        else:
            pass # or inform the user about bad username/password


class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        self.label = QtGui.QLabel()
        self.setCentralWidget(self.label)

    def setUsername(self, username):
        # do whatever you want with the username
        self.username = username
        self.label.setText("Username entered: %s" % self.username)


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)

    login = LoginDialog()
    if not login.exec_(): # 'reject': user pressed 'Cancel', so quit
        sys.exit(-1)      

    # 'accept': continue
    main = MainWindow()
    main.setUsername(login.username.text()) # get the username, and supply it to main window
    main.show()

    sys.exit(app.exec_())

【讨论】：

是的，这与我的方法几乎完全相同，除了您将逻辑移至 main 而不是让 MainWindow 管理它。每种方式都行之有效。

【解决方案5】：

不管你的描述如何，我认为你的 LoginWindow 应该是一个 QDialog，你的 StuffWIdow 应该是 MainWindow，并且像这样运行......

应创建您的 StuffWindow MainWindow（未显示）
调用login() 方法创建并执行您的登录 QDialog 作为应用程序 MODAL 对话框
现在启动 app.exec_() 事件循环，等待用户与登录交互
用户与登录对话框交互，对话框关闭的结果将允许您的应用检查其值并选择显示其主界面。

这里是一个简短的大纲：

class MainWindow():

    def login():
        loginDialog = LoginDialog()

        # this is modal. wait for it to close
        if loginDialog.exec_():
            # dialog was accepted. check its values and maybe:
            self.show()

        else:
            # maybe reshow the login dialog if they rejected it?
            loginDialog.exec_()


if __name__ == "__main__":

    app = QApp
    win = MainWindow()
    win.login()
    app.exec_()

【讨论】：