下拉列表框样式如图：

字体列表框样式：

 

 1 import sys
 2 from PyQt5.QtWidgets import QApplication, QWidget, QComboBox, QFontComboBox, QLineEdit, QMessageBox, QVBoxLayout
 3 import time
 4 
 5 class Demo(QWidget):
 6     choice = 'a'
 7     choice_list = ['b', 'c', 'd', 'e']
 8 
 9     def __init__(self):
10         super(Demo, self).__init__()
11 
12         self.combobox_1 = QComboBox(self)  # 实例化下拉列表框
13         self.combobox_2 = QFontComboBox(self)  # 实例化字体列表框
14 
15         self.lineedit = QLineEdit(self)
16 
17         self.v_layout = QVBoxLayout()
18 
19         self.layout_init()
20         self.combobox_init()
21         
22 
23     def layout_init(self):
24         self.v_layout.addWidget(self.combobox_1)
25         self.v_layout.addWidget(self.combobox_2)
26         self.v_layout.addWidget(self.lineedit)
27 
28         self.setLayout(self.v_layout)
29 
30     def combobox_init(self):
31         self.combobox_1.addItem(self.choice)  # 添加一个选项
32         self.combobox_1.addItems(self.choice_list)  # 添加容器中的参数。容器：可迭代的
33         self.combobox_1.currentIndexChanged.connect(lambda: self.on_combobox_func(self.combobox_1))
34         #选项发生变化时发出信号
35         # self.combobox_1.currentTextChanged.connect(lambda: self.on_combobox_func(self.combobox_1))
36         #当文本内容发生变化时发出信号
37 
38         self.combobox_2.currentFontChanged.connect(lambda: self.on_combobox_func(self.combobox_2))
39         #字体选项发生变化时发出信号
40 
41     def on_combobox_func(self, combobox):
42         if combobox == self.combobox_1:
43             QMessageBox.information(self, 'ComboBox 1',
44                                     '{}: {}'.format(combobox.currentIndex(), combobox.currentText()))
45             #combobox.currentIndex() 返回当前索引号
46             #combobox.currentText()  返回当前选项的文本
47         else:
48             self.lineedit.setFont(combobox.currentFont())
49             #单行文本编辑框设置字体
50             #combobox.currentFont()  字体选择框中当前的字体
51 
52 
53 
54 if __name__ == '__main__':
55     app = QApplication(sys.argv)
56     demo = Demo()
57     demo.show()
58     sys.exit(app.exec_())