pyqt QlineEdit 输入密码显示成圆点

使用自带的函数就可以实现：
lineEdit.setEchoMode(QLineEdit.Password)

import struct
from PyQt5.QtWidgets import (QMessageBox, QLineEdit)
from PyQt5.QtGui import QPixmap
{...}

class LoginWindow(QtWidgets.QWidget):
{...}
    def __init__(self):
        super(LoginWindow, self).__init__()
        # 加载ui文件
        loadUi('login.ui', self)
        # 设置背景图片
        background = QPixmap("img/login_background.jpeg")
        background = background.scaled(self.background_label.width(),self.background_label.width())
        self.background_label.setPixmap(background)
        # 设置输入密码框
        self.passwd_lineEdit.setEchoMode(QLineEdit.Password)
{.......}

def mainpage():
    app = QtWidgets.QApplication(sys.argv)
    login_window = LoginWindow()
    login_window.show()
    sys.exit(app.exec_())