如何让Tkinter Entry组件实现占位符与密码星号显示的正常切换

问题根因 #

你的代码存在两处逻辑错误导致失焦显示异常：

1. 失焦事件的show属性处理错误：focus_out方法中无论输入框是否有内容，都统一将show设为None，如果输入框有内容会直接导致密码明文泄露；如果输入框为空，插入占位符时也没有关闭show属性，导致占位符文本被渲染为星号
2. 占位符插入逻辑缺失：insert_placeholder方法没有同步关闭show属性，占位符文本无法正常展示

修复后完整代码 #

from tkinter import *
import os

class PlaceholderEntry(Entry):
    def __init__(self, master=None, placeholder="", placefg='grey', bg='white', fg='black', insertbackground="black", show=None):
        super().__init__(master)
        self.placeholder = placeholder
        self.placefg = placefg
        self.normal_fg = fg
        self.show_char = show
        self['bg'] = bg
        self['insertbackground'] = insertbackground
    
        self.bind("<FocusIn>", self.focus_in)
        self.bind("<FocusOut>", self.focus_out)
        self.insert_placeholder()

    def insert_placeholder(self):
        self.delete(0,'end')
        self.insert(0, self.placeholder)
        self['fg'] = self.placefg
        # 插入占位符时关闭字符隐藏
        self['show'] = ''

    def focus_in(self, *args):
        if self['fg'] == self.placefg:
            self.delete('0', 'end')
            self['fg'] = self.normal_fg
            # 获得焦点时恢复设置的隐藏字符
            self['show'] = self.show_char

    def focus_out(self, *args):
        if not self.get():
            self.insert_placeholder()
        else:
            # 有内容时保持字符隐藏
            self['show'] = self.show_char

os.system('cls' if os.name == 'nt' else 'clear')

root = Tk() 
root.title("entry")
root.geometry("400x400")
root.configure(bg='#222222')

c = ("#ffffff", "#222222", "#111111","#555555","#000000")

username = Entry(root, show="*")
password = PlaceholderEntry(root, show="*", placeholder="password", placefg=c[3], bg=c[2],fg=c[0], insertbackground=c[0])
username.pack()
password.pack()  
root.mainloop()

关键修改点 #

• 重命名了属性避免和内置关键字冲突，移除了无意义的self.none变量
• 插入占位符时强制关闭show属性，确保占位符文本正常显示
• 失焦时判断输入框状态：为空则插入占位符，有内容则保持密码隐藏状态

内容的提问来源于stack exchange，提问作者R Cuccurullo